RE: [AMRadio] National PW Dial
I may do this again Wayne as this has sparked and interest for me. A project of this type makes one appreciate the workmanship and engineering that goes into some of the old radios that tracked so well. Frequency counters are wonderful pieces of equipment but when you throw the switch on a 100KC calibrator and pull the VFO/PTO dial zero beat just as the dial mark passes zero, it really makes you feel good. John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Sara & Wayne Steiner Sent: Tuesday, March 13, 2007 6:13 AM To: Discussion of AM Radio in the Amateur Service Subject: Re: [AMRadio] National PW Dial I found that the variables in the command set series of transmitters are very close to straight line frequency. Some years ago I built a variable osc. using one of those caps and a mechcanical digital counter and was in within less than .5 khz over a 200khz band (160m). I of course had to do some trial and error plate bending. Over a 25 khz portion of the band and a small variable osc padder I could be "spot on". wayne , N0TE __ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
RE: [AMRadio] National PW Dial
I was able to get another tuning capacitor to work pretty close to the desired 1-500KC span once on the linier dial by making the tuning capacitor as a small part of the total capacitance of the circuit and by placing the tuning capacitor across only a portion of the coil and the larger part of the total capacitance across the whole coil. I could actually spread the band out on the high end if I wanted to. I was going to build a receiver using this circular linier dial I think it came from a surplus frequency meter or generator. Some one once told me that it had been done once and the individual that did it actually filed the plates down to calibrate it. I was going to do this as well I had mine working to within a few KCs from one end to the other (700 to 1200) KCs I was going to get out the files when the flood came and washed it all away. I even had a program for the computer to do a least squares analysis on the capacitor which I inputted data from a capacitance meter for 100 places on the dial. With some manipulation of some formulas and with the help of a Visual Basic Programmer friend, I was able to get it to draw a graph of the frequency to dial reading X,Y.. I was an intense project but a fun one. John, WA5BXO ___ __ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
RE: [AMRadio] Tube Data
Try this http://amfone.net/Amforum/index.php?topic=4837.0 John Coleman, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Brashear Sent: Sunday, March 11, 2007 8:25 PM To: 'Discussion of AM Radio in the Amateur Service' Subject: RE: [AMRadio] Tube Data Oops! Sorry, I meant 371B. Rick -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Brashear Sent: Sunday, March 11, 2007 8:23 PM To: AMRadio@mailman.qth.net Subject: [AMRadio] Tube Data I thought I had a manual for every tube I'd ever need, but I can't see to fond any info on a 571B rectifier. Anyone have the specs? Thanks, Rick __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body. __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body. __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
RE: [AMRadio] WTB: HV Transformer
Jack: I really think you should consider the solid state rectifier option for at least the other two diodes and go bridge with the XFMR. That you have. John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Schmidling Sent: Tuesday, December 19, 2006 8:31 AM To: Discussion of AM Radio in the Amateur Service Subject: [AMRadio] WTB: HV Transformer Seems like transformers are going the way of CW. After a month of looking, posting on 3 classified sites and several mail lists, Classic Radio Net and usenet, I am still looking for something as basic as 3000vct transformer. I can order one new from Dahl but that sort of takes the fun out of this but may have no other option. So last call. Jack K9ACT -- PHOTO OF THE WEEK: http://schmidling.com/pow.htm Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] the 3600 - 3635 spectrum
"Alternate spectrum from 3585 - 3600." Does this mean that we keep the 3600 and up for voice? Is the FCC saying these digital guys need to just move down? I have a lot of mixed emotions about the code exam being gone. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of D. Chester Sent: Friday, December 15, 2006 7:38 PM To: amradio@mailman.qth.net Subject: [AMRadio] FCC ADDRESSES ARRL PETITION FOR RECONSIDERATION,NO-CODE PROPOSAL Last part: Finally, today's Order resolved a petition filed by the ARRL for partial reconsideration of an FCC Order released on October 10, 2006 (FCC 06-149). In this Order, the FCC authorized amateur stations to transmit voice communications on additional frequencies in certain amateur service bands, including the 75 meter (m) band, which is authorized only for certain wideband voice and image communications. The ARRL argued that the 75 m band should not have been expanded below 3635 kHz, in order to protect automatically controlled digital stations operating in the 3620-3635 kHz portion of the 80 m band. The FCC concluded that these stations can be protected by providing alternate spectrum in the 3585-3600 kHz frequency segment. Action by the Commission on December 15, 2006, by Report and Order and Order on Reconsideration. Chairman Martin and Commissioners Copps, Adelstein, Tate, and McDowell. For additional information, contact William Cross at (202) 418-0691 or [EMAIL PROTECTED] WT Docket Nos. 04-140 and 05-235. http://hraunfoss.fcc.gov/edocs_public/attachmatch/DOC-269012A1.pdf __ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Component ID please
Well then that proves that the movement is indeed a 1ma movement. Now you need to remove the 500K ohm if you are going to be using it with an external 5Meg else you will be 10 percent off in measurments. You could also leave the 500K inside, and replace the external 5 meg with a 4.5 meg. The total resistance needs to be 5 meg to use a multiplier of 10 on the scale. If you leave the total resistance a 5.5 meg (5 meg +500K) then you will need to multiply the meter reading by 11 instead of just 10. That's too difficult. If you want a full scale reading of 2KV (multiply the scale by 4) then the total resistance should be 2 MEG. John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Schmidling Sent: Monday, December 11, 2006 9:55 PM To: Discussion of AM Radio in the Amateur Service Subject: Re: [AMRadio] Component ID please John E. Coleman (ARS WA5BXO) wrote: > Jack, > Check the meter with another meter and see if it is reading 1ma and is > accurate enough. Actually, with the new 500k in the meter, it reads 10v with 10v in. Couldn't think of anything with a higher DC voltage to calibrate with but at least is is functioning and in the ball park. js -- PHOTO OF THE WEEK: http://schmidling.com/pow.htm Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] RF Amp
I ran a pair if 304tls in push pull. I think the bias was around 500 volts and the grid current was around 150ma. I drove it with a pair of 812s in push pull at about 110 watts drive. The plate supply on the 304s was around 1600 volts and the plate current was 600ma. Output power was 790 watts. The modulator was four 813s in standard AB2 PPP configuration with 2700 volts on the plates. The tank coil was shortened up and capacitance added to get the Q up for the low load Z. That was an ether heater but it used a lot of power and it was large. The 450s do require a lot of filament and drive. They can be run at lower voltages but as I did the 304s but you will need to make special coils and have a lot of capacitance to 80 mtrs. Or the efficiency will suffer. Also lower voltages generally require a little more drive. These tubes are high current capable if driven hard. And just as point of reference the efficiency of a class C plate modulated amplifier must remain the same for all plate voltages with in the modulation voltage range or the modulation will not be linear. So if the plate voltage is 2000 the efficiency must be the same from at least 1 to 4000 volts. John Coleman WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] PW Supply
Brett: I have done that as well but have found that bigger resistors tend to be more accurate and don't change resistance with current as hand wound shunts some time do. You can use a 1ma movement at 1000ohms/V and get good measurements. But some times winding your own shunt is the best way. As a mater of fact, now that you mention it, I did that the last time I reworked my modulator chassis. Did you visit Tony's nice web site and the fine article he wrote about the Resonate choke input supplies? http://www.qsl.net/i0jx/supply.html I was especially impressed with the graphs. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Saturday, December 02, 2006 8:24 PM To: 'Discussion of AM Radio in the Amateur Service' Subject: RE: [AMRadio] PW Supply I usually wind thinner wire around something to give the correct shunt, cheaper and smaller then a big wire wound resistor... The power supply looks really nasty, it does not look like there are many good parts on it... Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of John > Coleman ARS WA5BXO > Sent: Saturday, December 02, 2006 8:41 PM > To: 'Discussion of AM Radio in the Amateur Service' > Cc: [EMAIL PROTECTED] > Subject: RE: [AMRadio] PW Supply > > It may be the only path to ground for the power supply and > measuring the > voltage across it may be the way to measure current from the > power supply. > > A 10 ohm resistor with 1 volt measure across it represents > 100ma current. > This is common practice for the way I measure power supply current. > > BTW I found this really neat site with some good info on > power supplies > http://www.qsl.net/i0jx/supply.html > Hats off to Tony, I0JX > > John, WA5BXO > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jack Schmidling > Sent: Saturday, December 02, 2006 7:12 PM > To: Discussion of AM Radio in the Amateur Service > Subject: [AMRadio] PW Supply > > > I am having some quality time with my new supply and have lots of > questions about things I do not understand. > > First one is, this is a choke input with a pair of 4mf's across the > output of the choke and a monster 100k bleeder. > > What bothers me is that there is a 10 ohm, many watt resistor between > the negative side of the caps and ground. > > What is this for? > > js > > > -- > PHOTO OF THE WEEK: http://schmidling.com/pow.htm > Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver > http://schmidling.com > > __ > AMRadio mailing list > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Partner Website: http://www.amfone.net > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > > > > __ > AMRadio mailing list > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Partner Website: http://www.amfone.net > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] PW Supply
It may be the only path to ground for the power supply and measuring the voltage across it may be the way to measure current from the power supply. A 10 ohm resistor with 1 volt measure across it represents 100ma current. This is common practice for the way I measure power supply current. BTW I found this really neat site with some good info on power supplies http://www.qsl.net/i0jx/supply.html Hats off to Tony, I0JX John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Schmidling Sent: Saturday, December 02, 2006 7:12 PM To: Discussion of AM Radio in the Amateur Service Subject: [AMRadio] PW Supply I am having some quality time with my new supply and have lots of questions about things I do not understand. First one is, this is a choke input with a pair of 4mf's across the output of the choke and a monster 100k bleeder. What bothers me is that there is a 10 ohm, many watt resistor between the negative side of the caps and ground. What is this for? js -- PHOTO OF THE WEEK: http://schmidling.com/pow.htm Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] 5691, 5y3's for sale
Opps Brett the 5691 is equivalent to the 6SL7 but I could build around that. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Friday, December 01, 2006 8:32 PM To: 'Discussion of AM Radio in the Amateur Service' Subject: RE: [AMRadio] 5691, 5y3's for sale I have a bunch of new tubes in boxes that is way more then I will need, and I am running out of space. I have 15 5691's (industrial 6SN7) And 9 5Y3 rectifiers. All US made, RCA, Philips, GE. Anyone need any of these? Brett N2DTS __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Schematic
Maybe if it is not to complex, you could draw the circuit, reverse engineer it so to speak. Is this device made of two oscillator circuits mixed linearly and are they phase shift oscillators or do they have LC circuits. Just curious John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Brashear Sent: Friday, December 01, 2006 4:34 PM To: Discussion of AM Radio in the Amateur Service Subject: Re: [AMRadio] Schematic Thanks John. That was my first inclination and one of them was headed south. However, it has only two and I replaced both with known good ones, but she still won't sing. Rick __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Class C finals
The Drive on a class C circuit is set to swing the conduction of the tube from cutoff to saturation with in a RF cycle. In this type of service, the tube is cut off for about 290 degrees and at saturation for about 70 degrees of the input RF cycle. I use the word "ABOUT" because obviously there is some time that it is in transit and this is where the plate dissipation is greatest. Once the bias and grid current have been achieved by the grid leak due to the drive then increasing the drive has very little effect on the output. Decreasing the drive below the point where output begins to drop will result in the service not being class C any longer. That is to say that the ratios of conduction angle for saturation and cutoff are no longer proper for the class of service and efficiency will suffer. I'm sure since the 2E26 does not have the space charge that the 6146 has, then it is designed to run at lower bias voltage and RF drive. Whether you run it a 2ma or 3ma will have very little effect on the output or the efficiency. If you're going to pull the loading back to draw less plate current (a function of the tank loading circuit) when the plate tuning is dipped, then that could be done with either tube. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jack Schmidling Sent: Monday, November 13, 2006 10:38 PM To: Discussion of AM Radio in the Amateur Service Subject: Re: [AMRadio] Class C finals John Coleman ARS WA5BXO wrote: > So it would seem that if you replace the 6146 with a 2E26 then in > order to get the proper operating parameter for the 2E26 one would need to > reduce the loading. So why not just reduce the loading on the 6146? The suggestion was to reduce the drive on the 2E26 and load it to where it is comfortable which suposedly would be at 15w. js -- PHOTO OF THE WEEK: http://schmidling.com/pow.htm Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Class C finals
Jim, you and I are on the same track here. Many folks make the assumption the final tubes in a class C circuit are what determines the power. I look at it from the other end, in that it is the voltage and loading which determines the power and you have to find a tube that can handle the switching and plate dissipation. So it would seem that if you replace the 6146 with a 2E26 then in order to get the proper operating parameter for the 2E26 one would need to reduce the loading. So why not just reduce the loading on the 6146? To me, it is like replacing my 250th with a 100th and then being forced to reduce the loading to keep the tube in the proper operating parameters for efficiency. Where as if I had a rig designed for a 100th and then plugged in a 250th instead all plate parameters could remain the same. It would be interesting, if some one wanted to try it, that a DX100 using a pair of 6146s could be tuned to 100 watts output and then one of the 6146 removed and the user would have to reduce the loading in order to keep the remaining 6146 from meltdown. And if the reduction in load was made to the point that the 6146 was drawing 1/2 of the plate current and output was 50 watts or less then plugging in the next 6146 would not increase the power unless the load was increased again. At least that is my theory! I wonder if any one has tried the ultra efficient class C circuit that can achieve 90% efficiency. It involves, 3rd harmonic shaping circuits in the grid tank, and 3rd harmonic traps in the plate. RCA built a broadcast transmitter using this design. The theory is that you square up the input wave form so as to switch the tube on and off. The third harmonic squaring of the input wave causes this switching time to shorten up a lot. The 3rd harmonic trap in the plate tank represents a high Z to the third harmonic and passes the fundamental to the main tank and load circuit. Using this circuit a single 6146 could put out 90 watts with 100 watts input and run cooler than the pair in the DX100. It might not be quite this good since it is a tetrode with an indirectly heated cathode. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Candela Sent: Monday, November 13, 2006 5:14 PM To: Discussion of AM Radio in the Amateur Service Subject: Re: [AMRadio] Class C final tube swaping John, You made several good points with your push pull amps. One big difference here is that the 2E26 is indirectly heated, and possesses an indirect cathode with limited emission capability. Those directly heated thoriated tungsten filament tubes you mentioned are all high pervience whereas the 6146, and 2e26 are not. So replacing a 6146 running 90 watts DC input Class C with a 2E26 will not give you the same power input or output since the 2E26 won't be able to swing the plate to a low potential at high current like the big brother 6146 did. I would worry about the 2E26 turning red, and going into sweep tube heaven since the efficiency will be poor unless the plate load impedance is lightened up. For those who have tried this, how well did the 2E26 modulate? Ever look at the pattern in trapezoid mode? ;-) Jim __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Class C final tube swaping
I do not have a ranger or have I had a ranger, but I just can't see how replacing a class C tube will change the power. As far as I know the ranger is a class C output and not a linear amplifier. To me a class C circuit is a switch which gains its efficiency from the fact that it doesn't spend much time in between saturation and cutoff. The perfect device would be a switch that is either on or off and is switched on and off at the carrier frequency. Tubes are not perfect switches hence they dissipate some heat in transit from on to off and back. Changing the loading or the supply voltage will change the power. In other words putting in more lights or bigger lights is increasing the load making more light in the room. Changing the supply voltage up or down will also change the brightness of the room. Putting a larger or smaller switch in the wall will have very little effect until the switch is made too small then it will heat and burn up. Here is an example that I am familiar with. I have run pairs of 813s, 812s, 304TLs, and now 250THs. I have yet to see any difference the output or tuning when I turn off the filament in one of the pairs. I first had this happen on the rig with the pair of 304TLs. I ran 1700 Volts at 550ma total plate current from the power supply. The power supply was separate and had its on meters on it. I addition the 304TLs had separate plate chokes and were shunt coupled to the tank circuit. This allowed for each of the 304 to have its on plate current meter. When all was balance right each tube pulled 225ma from the power supply. One day the heater connection on one of the 304TLs went bad as they or known to do sometimes and nothing changed on the scope. I didn't even know it until I happened to look up at the rig and noticed a lot of extra color from one tube and the other was dark. The power supply current did not change and the one tube that was left was doing all 550 ma of plate current by itself. So I went from a VIRTUAL 608TL to a 304TL and no change it operation except more color on the one tube. I did the same thing on the 250th rig except I broke a tube. So I just pulled it and only had to re-dip the plate because of the slight change in capacitance from the missing tube. No change in output no load change. So will some one please tell me the theory of how putting a smaller tube in the ranger will by its self make the ranger half power And please don't misunderstand me here, I'm not saying it can't, I just want to know how it does it. It just seems to me that putting in a smaller switch will just ensure that you will change the switch more often. I have theorized that the 2E26 must pull more screen current than the 6146 and there by have less voltage on the screen and thereby have less acceleration to the plate current. In other words similar to reducing the screen voltage on the 6146. But this would cause a change the parameters and conduction angle requiring a reduced load in order to maintain the proper Q in the tank. Improper Q, conduction angle outside the normal 70 degree window, these things can cause a lot of improper modulation characterizes. Maybe I'm just too picky! John, WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Ranger... good news, bad news
That's a good idea Gary. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gary Schafer Sent: Monday, November 06, 2006 6:56 PM To: 'Discussion of AM Radio in the Amateur Service' Subject: RE: [AMRadio] Ranger... good news, bad news Put a T connector on the output rf connector and put a capacitor on one side of the T. 73 Gary K4FMX __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Ranger... good news, bad news
I was going to comment earlier about the statement that this Ranger would not hold it's on against the rice box with the SB200. As Jim pointed out there should not be but a DB or so difference if the ranger is working properly and properly tuned. I am curious as to what power his ranger will put into dummy load and what the modulation looks like. I think I read in this thread about someone reducing the drive on the Ranger's grid. That is a sure fire way to ruin the output tube (6146). The single 6146 in class C service as it is in the Ranger should have 2.5 to 3 milliamps of drive on it at all times. Do not reduce the grid current drive to reduce power on the Ranger. If memory serves me right the 6146 is to be used at about 65 watts plate input on AM plate modulation. It should be putting out between 40 - 45 watts carrier and develop about 180 watts PEP. (Could be a little more with a good modulation XFMR) That's only about 2-3 DBs below what the SB200 will do as an AM linier when operated properly. Now 3 DBs is not to be taken lightly when the going is rough but if your going to do a lot of work for a DB or 2 then put the work in the antenna or a bigger rig that will get you 10 DB gain. I have used the SB200 on AM and it does OK but I would not want to do it for a long time. Those tubes get real hot. I use the SB200 as a driver for my big rig. The input to the SB200 is about 5 - 10 watts and the output of the SB200 is about 50 - 70 watts carrier this drives the grid of my big class C plate modulated final. But even using the SB200 to put out 50 - 70 watts it get real hot and the tube show some color. I think the best thing I can do to increase the efficiency of the SB200 at low power, is to reduce the plate voltage to about 1500 instead of 2500. I added a switch to the front panel of mine to increase the bias voltage making it harder to drive. I thought that this would decrease the conduction angle enough to reduce the heat but the trouble is that the plate is still not reaching saturation at the low power level so I figure that if I reduce the plate supply voltage and increase the drive then I can come closer to the non linear class C service for continuous CW and the efficiency will surly increase. The idea is to use the rice box rig at low power so it will last a long time and have the SB200 to make up the slack. But I want it to last a long time as well. BJ and I like the flexibility of this type of operation. That is to be able to flip some switches and use the SB200 as linier on SSB as it was intended and then flip the switches back so as to lower the output but raise the efficiency for continuous carrier operation as required by the big class C final. We have been operating it linearly with the 2500 volts supply and reducing the drive from the rice box carrier source but it has always bothered me that it is so inefficient and those tubes show color. As I recall the PS in the SB200 is a voltage double type circuit perhaps a little circuit change up with some HV switches might be in order here? Any Ideas on this? John, WA5BXO BTW the stock plate RF choke in the SB200 is NOT large enough on 75 mtr and a lot of RF gets back into the PS causing weird AC modulation at low carrier levels. BJ and I thought it was the Filter Caps so we got new ones. No help. We found that the weird modulation on the output carrier would come and go at different levels of drive at low power and only on 75 mtrs. We measured the DC at the POWER supply B+ point as it went through the chassis to the plate choke and found some RF there and guess what the RF was getting back to the diodes in the PS and modulating with the AC. It was real weird. Placed a RF choke under the chassis and an extra RF bypass cured the whole thing. 73, John, WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] 813 filament voltage
Hi Steve: In addition to the things that Jim (JKO) said and to answer your question "is 8.5 volts OK?", (assuming your meter is correct) no 8.5 volts is not OK. Not only will the emission be low and power out low but the tubes will suffer from a special illness that occurs from insufficient heater voltage. I do not know the details of this illness but Don, K4KYV can tell you more about it. Below is a paragraph segment from http://www.transfixr.com/strafe_tube.htm section A: cathodes paragraph 3. Lifetime of cathodes: "Operate it too cool and life may be shortened (especially in thoriated filaments, which depend on replenishment of thorium by diffusion from within the filament wire). A few researchers have observed that the lifetime of an oxide-cathode tube can be greatly increased by operating its heater at 20% below the rated voltage." John, WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] 220 volt AC Power Question
That is the way I am running mine Jim. I have two power supplies (MOD/FINAL) 120 VOLT AC each and I run one from each leg of the 220 and a common line for the return. (Three Wire). The plate relay/contactor is a three phase relay/switch but only 2 of the contactors are active of course. The earth/safety ground is a separate wire that is connected to a ground stake outside the shack. I guess I could have run separate return along with each hot leg but I don't know why I should. I use a clothes dryer plug and pigtail for mine. The Filament XFMRS for the rectifiers, finals, and modulators all run from the same phase as the modulator plate supply. And the final plate supply is on the other phase. There are breakers at the pole and a 3 phase breaker in the rig. Only two lines in use; Common stays connected at all times. By the way I do not use a transformer for bias supply for either the final or for the modulator. Bias supply comes from diodes that are connected through limit resistors from the 120V AC hot line. Chassis is connected to common AC and earth ground at all times. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Monday, October 30, 2006 7:10 PM To: Discussion of AM Radio in the Amateur Service Subject: [AMRadio] 220 volt AC Power Question Hi all, I am building an amplifier that has a combination of 220 volt and 120 volt transformers. The HV plate supply is 220V, and the rest is 120V. I will be keying the plate supply. My 220V outlet has phase, phase, and ground. There is NO neutral. The outlet is not a GFCI outlet so ground current will work, BUT. The BUT here is whether this is legal with the National Electric Code? Before you say NO, consider the electric clothes dryer. These all run off 220V, and have 3 prong power cords. I have heard that in some dryers there are 120 volt loads (lights, and timer) as well as 220V (heater and motor). If this is true, then my approach must be OK so long as my power switch uses a DPST switch and (double fuses)to insure everything is off when it is in the OFF position. Comments please... Jim JKO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] JOTA report
Report on the JOTA operations from Galveston Texas. 20 and 40mtrs were really hopping. We were running a TS430s into a Johnson matchbox connected to a open wire feed line to a center fed 100 ft doublet stretched between to 30 ft towers. Propagation was all over the place. On Friday, right after getting the rig and antenna up, I called a station in chili CE/VE7SV got a 59 report. Worked stations all over the country on both 20 and 40 meters then in the afternoon of Saturday the 21st of October, I was calling CQ JOTA from Galveston Island and Pippo, IK7YCE, from Italy called me with a great report. The Boy Scouts and I almost lost all composure. It was a great JOTA weekend except for the rain Saturday morning and the rain and wind Sunday morning. It rained so hard that some of the tents flooded on Saturday morning and then after moving the tents and equipment it rained again at a little after midnight on Sunday morning and then the cold wind came in from the north at about 40-50 mph and pulled the tent stakes out of the already soak ground and blew a number of tents around including the scoutmasters which completely collapsed. He didn't think it was as funny as the rest of us did. So in summary it was good radio and bad camping. 73, John, WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] TS430 as VFO on a KNIGHT T60
Yes, by all means give it a whirl. That's how discoveries are made. Funny, that you should mention the SB200 in that way. BJ, WB5PKD, and I are using the SB200 to drive the grids of the 250THs. We drive the SB200 with a modified TS820. The TS 820 put about 10 watts into the SB200 and the SB200 puts about 60 watts into the push pull grids of the 250Ths. We have checked the SB200 out as an AM linear and found it to be equivalent to a pair of 6146s plate modulated, like a DX100 or Apache but with better audio using the TS830 or the modified TS820. We modified the TS820 so that with the flip of a switch it would bypass the SSB filter and allow carrier injection while in the LSB mode position. This makes it a great AM rig for about 15-20 watts carrier. As you found out the plates on the finals of the SB200 or red but they are a little red at idle current with no carrier. We tried to put extra bias on the SB200 to bring the plate current to cut off and a little past cutoff. Then applying more drive to get the carrier out that we wanted but with a little more efficiency. It helped some but then required more drive from the TS820 causing it to heat up a little more. I guess there is no substitute for bigger tubes. HIHI so we just run it a little lower and limit the Xmit time. As for control carrier, I would rather run SSB. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of KA5MIR Sent: Sunday, October 15, 2006 1:35 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] TS430 as VFO on a KNIGHT T60 Hello Jack, Controlled carrier has tradeoffs. You are trading reduced linearity and tricker audio adjustment for greater PEP. Not that it can't be done and sound reasonably good. Another point is that tubes with zirconium or titanium on the plate NEED to get red to getter properly. I'd be more concerned about the power supply than the red plates. But that's just SSB amps in general. I don't have any experience with the SB200. It would probably be easier and more productive to just reduce the carrier power on the 430 until you're happy with the amp. I doubt anyone on the other end would notice 20 or 50 watts difference and your audio would probably sound cleaner too. But the main thing is to have fun and enjoy your radios. If you want to put the T60 on the air, by all means drive it with a little carrier from the 430 until you get your crystals. You won't have to worry about being on frequency. :) 73' KA5MIR On Sunday 15 October 2006 11:42, Jack Schmidling wrote: > My thoughts on an advantage of the T60 is that, as it has > controlled/suppressed carrier, the idle power is a lot less than the > TS430. As a consequence, I could drive a linear (SB200) a bit harder > and get more power out of it than when using the 430. > > When running the 430 at about 15 watts, and a plate current of 150 ma on > the amp, the plates get redder than I like. Seems like I should be able > to increase the input significantly with the T60 before the plates got > to the same temp. > > Is this correct reasoning? > > I think I will just get some xtals for the T60 as I am getting a Ranger > soon. > > js __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] TS430 as VFO on a KNIGHT T60
For using the Kenwood TS430 as a VFO to go into the Knight T60, yes you can use the AM mode with audio gain turned down on the TS430 and put a dummy load on the TS430. I don't remember what voltage is required at the T60 input. My guess would be 5 - 10 volts PTP but it has been to long ago. If the TS 430 is attached to dummy load and the input to the T60 then you will need about 1/4 watt on the dummy load to get the 10 volts PTP at the T60 input. A 2 watt 50 Ohm resistor across the input of the T60 should serve as the dummy load fine. The "Transverter" output with a step up XFMR or tuned network is a better idea. However, the best idea is to use the AM mode of the TS830 at about 20 to 25 watts carrier output to the antenna and forget the T60, except for a nostalgic piece. I used a T60 as a novice and as a general class back in 1962 - 1964. It was great at the time. The controlled carrier modulation was barely acceptable so I built the external modulator using a pair of 807s. That made a tremendous difference.The output of the T60 in CW mode is only about 35 - 40 watts MAX and in AM mode is about or less than 10 watts carrier with no modulation and full controlled carrier type modulation the PEP = 35 - 40 watts. If you build and use an external plate modulator for the T60 and run the T60 at full load in CW mode modulating it to 100% with the external modulator the BEST output you can obtain will be a 35 to 40 watt carrier with PEP = 160 Watts. The TS430 will only be about 2 DB below that when the carrier level is set at 25 Watt carrier output you will get 100 Watt PEP output when modulated. The TS430 has excellent AM with very nice modulation characteristics. The TS430 will be narrower when compared to the T60 for 3 KHz modulation because of its great linearity. The ALC will provide a limit for over driving the RF stages. Even if you reduce the carrier to 10 Watts and produce 100 watts PEP with modulation, it will be narrow because it will produce DSB energy without respect to the carrier (balance modulator operation) therefore you will not see clipping of the carrier as you might with full high level modulation. As for the T60, I'm not saying "don't do it". You will want to make your on observations for the experience. But, the TS430, when operated properly on AM, will get you better signal and audio reports and keep your band neighbors friendly. John, WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Seeking advice on testing modulation transformers
The RCA 1:1 modulation XFMR I believe is good for only 200 ma in its secondary. Don, K4KYV has described a method of removing or reducing the core gap to make this XFMR capable of very good low frequency response but it will then require a modulation reactor and coupling capacitor because the secondary current handling before core saturation will decrease drastically. The STOCK XFMR will provide fairly good audio down to 200 or 300 CPS depending on the load and secondary current. My understanding from Don was that the primary use of the XFMR was for a tone modulated CW rig or MCW as I think it was called. If this is the case then all it had to pass was a single CW audio tone. I have used the STOCK XFMR in the past with pretty good results, and certainly good audio especially in the communication range but don't expect it to do HIFI from 50cps to 10,000cps and it would be best to use a reactor with it even if you don't modify the core gap. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mark Foltarz Sent: Wednesday, September 20, 2006 5:53 PM To: amradio@mailman.qth.net Subject: [AMRadio] Seeking advice on testing modulation transformers By the way, does anyone have any experience using the RCA 5500 5500 units? TNX de KA4JVY Mark __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Vintage recordings and preservation
I see Otis from time to time still I will give him a call and see if we can dig up some of the old recordings. I have the equipment to do the transfer to digital. I do it all the time for customers. John, WA%BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Residule Magnatism
In the cannon laser jet SX series printers released as HP Laser Jet II, and other brands as well, there is a solenoid device which releases a clutch which then allows the paper pickup rollers to move paper through the printer. These devices have a felt pad between the armature and the pole piece which I once thought was only to keep down noise. Then one day I begin to see a lot of sticking solenoids and investigated the failure. The felt pad along with the glue that held them in place had changed to a mushy substance that was not releasing the armature and so it would continue to feed paper after all the printing was done. I said to my self, "Well I will just scrub that stuff away and let it make a little noise, so what". Well it turned out that with out the non magnetic material in between the armature and the pole piece the residual magnetism would not release the armature either. So I glued a little piece of thin plastic in place and all was well. It was a little noisier that the felt pad but not bad. John, WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] acustical damping
"Cool tubes" reminds me of an old friend who even though is silent key, I will not say his name or call. I had a lot of respect for the gentleman but this was classic. He had wound a very nice ultra large modulation XFMR and it worked wonderful but was prone to talk back. K5SWK suggested that he submerge it in oil so our friend purchased a large Styrofoam ice chest and put the XFMR in it and filled it with oil. The acoustical damping was great but the oil would seep through the Styrofoam and leak on to the wooden garage floor. The floor was old and not too good so he really didn't mind too much. He just added more oil. Later he put in a wooden dipstick. We all wondered how many transmissions he got to the quart. John
RE: [AMRadio] Cool tubes
Now that is what I call ham radio ingenuity! Way to go Bob. If for no other reason just to see if could be done. It reminds me of my experiment to water cool the 4CX300s. I won't bore you guys with that again. 73 John, WA5BXO -Original Message- On Behalf Of W1EOF Sent: Monday, August 21, 2006 10:26 PM Subject: [AMRadio] Cool tubes After a discussion about crazy application of tubes I got Bobs permission to post these two pictures on a webpage. Figured you might enjoy a... pair of water cooled 6L6s: http://www.hamnutz.com/w1eof/n2ixk/ 73, Mark W1EOF
RE: [AMRadio] Mobile RCVR converters
K5SWK, Otis, had built several, band switched, 80, 40, 20 mtr converters using 12 volt tubes. These were the tubes that you found in the hybrid car radios. These car radios were all tube except for the solid state output stage. I think they were used about 1960 to 1965 in GMC vehicles. You historians may pin this down a little closer. He built the first one for himself and then about five or six for other mobile hams in the Houston area. These special tubes used 12 volt heater supply and 12 for the plate supply, no vibrators or power converters. The mixer/osc was one tube and a RF stage was another. He incorporated a small amount of adjustable regeneration and adjustable gain in the RF stage. The RF tune was extremely high Q and was able to reject very strong adjacent channel signals. It would go into blocking while sitting in a drive way and transmitting from the big rig in the house but all you had to do was tune the RF tune off resonates and the blocking would quit. It was also very sensitive probably due to the regeneration. In the house, Otis ran a single 833 at a kilowatt input. The house 80 mtr antenna was up about 70-80 ft high and was near flat top. While the big rig in the house was transmitting, he could burn out a #47 lamp connected to mobile antenna yet not damage the RF stage in the converter when it was connected. It really was the best converter I had ever tuned and heard and you could almost cover the face of the thing with your hand. I can't recall all the people that had one but I know that Ronnie, K5MKB, and Bill, WB5UMJ, did. He later built another for him self that had an OSC running at about 1600KC for SSB/CW reception. With the old one he had to engage the "SPOT" function of the XMTR to copy CW or SSB. When he decided to build the new converter, he had not had a mobile rig for about 15 years. I think he gave the old one away. He said he was not going to build a XMTR just for the "SPOT" function when all he wanted was to "read the mail". John, WA5BXO
RE: [AMRadio] Re: help on email
Don, K4KYV, sent me a reply direct and said he was not even able to post reply via the reflector using the text of my message. Really weird. John
RE: [AMRadio] on the air tonight
Hi Jim Probably around 3875 to 3890 in the evening is all I can say on time but I will look for you. Call me now if you can. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Candela Sent: Saturday, June 24, 2006 11:17 AM To: Discussion of AM Radio Subject: Re: [AMRadio] on the air tonight --- John Coleman ARS WA5BXO <[EMAIL PROTECTED]> wrote: > Hey Don, K4KYV > I may actually be on the air tonight if any one > wants to fight the QRM. > John, WA5BXO > Hey John, Any idea what time, and frequency? Jim JKO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] help on email
I sent message2 with out the "HIHI", again and it still bounced again. John, WA5BXO
[AMRadio] help on email
This is really strange. I can't seem to get a certain message to go through regarding something that Don, K4KYV, was talking about. So I posted the message on my web site. All of the other messages that I send go through fine. There must be a word in the txt that the reflector doesn't like? Please go to http://wa5bxo.shacknet.nu/reflector to see the messages.
[AMRadio] on the air tonight
Hey Don, K4KYV I may actually be on the air tonight if any one wants to fight the QRM. John, WA5BXO
RE: [AMRadio] DRAKE L-4 Amp
Bob Regarding the need for the 100K pot: Is The Pot Open? Or Is The Switch bad? I may have some thing that will work. Is the pot a linear resistance movement or logarithmic. My guess is that it is linear but the best way to tell is to set the pot at the half way point between extremes and then measure the resistance from the wiper to one end. If it is approximately 50K ohms, then it is linear. Even if one end is open the other end would still measure about 50K ohms. On the other hand, if it measures around 80 or 90K ohms from one side to wiper, or if it measures around 10 to 20K ohms from one side then it is a logarithmic. I think I have some 100K pots but will need to check them and see if one has a switch. What are the physical dimensions? John, WA5BXO
RE: [AMRadio] Ferroresonant transformer revisited
They are also called "CVT" (for Constant Voltage Transformer) I think or is there a slight difference that I am not aware of?? John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rick Brashear Sent: Tuesday, May 09, 2006 7:03 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Ferroresonant transformer revisited I believe they are one and the same, Don. Sola is a manufacturer of ferroresonant transformers. Rick/K5IZ Donald Chester wrote: > > This sounds similar to my experiences with a Sola constant voltage > transformer. Is that what a ferroresonant transformer is? > > Don k4kyv > > __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Ferroresonant transformer revisited
That's a great idea Jim, about using an RF amp meter for non sinusoidal wave forms or even DC. I've only had three or four of those but never saw two that read the same. I was beginning to think that a thermometer in the dummy load box might be calibrated just as well. HIHI Maybe I just don't have good ones. John, WA5BXO
RE: [AMRadio] Ferroresonant transformer revisited
Zenith, GE, and Sylvania TV (older tube versions) sets used the Ferro resonant transformer or Constant Voltage Transformer (CVT) that had a special winding with about a 1 to 4mf capacitor across it to saturate the core. This was there answer to the problems of picture shrinkage when people's air conditioner kicked on. They still needed a HV regulator to prevent blooming when the brightness was turned up. The CVT regulated the output voltage for input voltage changes but did not regulate much against load changes. These things are used by carpenters when they need to run a circular electric saw in an area where they need 100ft of extension cord to get power to the saw. When the saw bogs down in wood it draws more current and the extension cord would drop 20 volts or more. The CVT would be placed at the end of the extension cord and the saw plugged into the CVT. The current will drop on the extension cord to 90V but the CVT would hold the voltage up to 120 on the saw. I found these devices to be very useful in the shack to run the receiver and XMIT VFO. I always had to retune the receiver after transmitting and the VFO would drift slightly during XMIT because of the slight filament voltage drop. So I ran separate filament XFMR for the VFO and plugged it into the CVT and ran the receiver from the CVT as well. This ended both problems. I made my CVT from one of the old TV set transformers. One of the manufactures even put theirs on a separate chassis which made it easy for me. These XFMRS had cooling fins around the core and they did get hot. At the time, the US was not into the conservation mode. Here is a google link to a bunch of good info. www.google.com/search?hl=en&lr=&q=constant+voltage+transformer&btnG=Search SOLO was a major manufacturer of the ones used by carpenters. John, WA5BXO
RE: [AMRadio] antenna tuners transmision lines and more
You are correct Gary, it is very confusing to many and I was one confused guy for many years. It's not easy to get a grip on things of this nature. Invisible radiation and weird parts that have no movement, makes it all seem like wizardry and magic. Of course this is what makes it fascinating. I'll just add some more to the confusion. I am by no way a XPERT on this stuff but I have been told that I have a way with words as long as I can get a spell checker working. I have been asked to do some of this writing. I feel that I should share this with others and I have chosen this place to do it. I don't have a lot of opportunity to go get on the air much any more. I get stuck here at home watching kids once in a while and so this is when I type up these long stories. So please excuse the long winded transmission here. I hope some one gets something from it. Old Wives Tales (Misleading statements) FALSE STEAMENT #1 -- A high SWR reading is an indication that a lot of power is wasted and not being radiated. - TRUE STATEMENT --- SWR is the ratio of currents measured at physical points on a transition line. It is the ratio of the maximum current on the line verses the minimum current on the line. These two physical points will be 1/4 electrical wavelength apart. They do not necessarily have to be at the load end or the source end. IF the load end is representative of a pure resistive load then the SWR will be the ratio of the load resistance to the line characteristic impedance. If the load resistance is non reactive and equal to the line characteristic impendence then the SWR is 1:1 and current will be the same at any point on the transmission line that you care to measure it except for the normal loss due to line characteristics. Even a perfectly matched load:line such will have slightly less current and voltage at the load end than at the source end although as some one earlier pointed out, "It is generally a negligible difference". It would need to be a very long line to be significant on 80 or 40 meters. FALSE STATEMENT #2 --- There is no need for a tuner if the antenna is resonate and the line is matched. TRUE STATEMENT -- If the antenna feed point is equal to the line Z and the transmitter is made to work into this load then there may be no need for a tuner. This is an almost impossible task as some one pointed out earlier, and even if it were to be done it would only be true for a very small range of frequencies. QSY would be a compromise. FALSE STATEMENT #3 --- Tuners waste a lot of power and just make the transmitter think the antenna is right. TRUE STATEMENT --- A tuner consists of coils and capacitors neither of which by mathematical definition consumes energy. The adjustments of the coils and capacitors change the phase as well as the voltage to current ratios of input and output. The slight amount of energy that may be consumed by tuners is generally so negligible that it is very difficult to measure. In some cases a tuners components maybe made of poor quality material and too small for the job. These types of components will get hot. Heat is an obvious point of loss. I had a small MFJ tuner that was manufactured some years ago. It was just a small external Pi-Net device and I found it to have a measurable insertion loss. It turned out to be the rivets that held the connectors on the little chassis. I soldered braid across the connectors to the chassis and then the loss was then immeasurable. Modern solid state equipment is designed to work into a 50 ohm non reactive load. Connecting a dummy load of 60 ohms instead of 50 ohms will cause the rig to put out less RF current and make the automatic drive level circuitry start pulling back on drive prematurely. If the load becomes slightly reactive as well then the RF production will decrease rapidly. A tuner is nearly a must for these rigs. In tube type XMTRs the use of toroidal transformers for the output is impossible because of the high output Z of tubes. These rigs used instead a Pi-NET or link coupled tuned circuitry to do the job of matching the tube to the low impedance output. This type of circuitry could match a relatively wide range of impedances from 25 ohms to several hundred ohms as well as compensate for some reactance. Because of this an external tuner may not have been necessary especially if confined to one band on one antenna. A lot of folks put up multiple antennas one for each band or used a multiband trapped dipole or some other multiband radiator with a single coaxial down line. The Pi-Net in the rig did all the compensation for them. But with solid state rigs and no internal tuning it would be an near necessity to have an external tuner if nothing more than a small PI-Net tuner such as the one I had from MFJ Having to do with the conservation of energy laws. Here are some facts. 1. High quality capacitors (especially air or vacuum type with good al
RE: [AMRadio] Zepp Antenna
Your right Larry, unless it is very large. I thought it might be an air balun. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Larry Will Sent: Tuesday, April 18, 2006 9:04 PM To: Discussion of AM Radio Subject: RE: [AMRadio] Zepp Antenna The large inductor probably will have less loss than the torroid. Also if overdriven, torroids can generate harmonics. Larry
RE: [AMRadio] Zepp Antenna
I suppose the lengths I suggested just would not work in your arena. The large balun is probably a good idea. 73, John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of uvcm inc. Sent: Tuesday, April 18, 2006 5:23 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Zepp Antenna Tried a large balun and a 10 turn inductor, both worked; now I need to find out which method will work the best, great learning process Brad KB7FQR -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John E. Coleman (ARS WA5BXO) Sent: Tuesday, April 18, 2006 2:33 PM To: 'Discussion of AM Radio' Subject: [AMRadio] Zepp Antenna Hey Brad, KB7FQR How did the antenna work out? Have you made any more changes? John, WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] wanted antenna analyzer
This is an edited revision of the email I sent earlier because the first one did not read properly due to improper spelling and grammar. I was in a hurry! Sorry Brad, The sum of one ant leg and the feed line needs to be about 120 ft or doubled for 240 ft so as to come out with a high Z for the Johnson match box. Your antenna at 120 - 150 ft is a low Z center fed doublet and with a half wave of feed line (135 to 110 ft) it will come out as a lo Z feed point at the bottom. The Match Box will not work well on 80 meters feeding a low Z. Here are some examples of what you should have. These all assume you are using open wire feed line with a very high velocity factor. I did all my experiment using feed line made #12 wire spaced at 6 inches about every 2 ft. using phenolic spacers. Later I found the 5.25 in drive bay plastic covers from computers works great for spacers as well, but they do get brittle in the heat and sun light. 1. - 60 ft per leg on the doublet (120 ft antenna) and 60 ft of feed line or optional 180 ft of feed line (that's an extra 120 ft -.5 wavelengths option in each example) 2. - 75 ft per leg on the doublet (150 ft antenna) and 45 ft of feed line or optional 165 ft of feed line 3. - 45 ft per leg on the doublet (90 ft antenna) and 75 ft of feed line or optional 195 ft of feed line 4. - 120 ft per leg on the doublet (240 ft antenna) and no feed line (Puts the Match box up at the center of the antenna, not practical) or 120 ft of feed line. Example number 5 is cool because the full wave antenna will represent a very high feed Z at its center and if you wanted to put the Match Box up in the air and run coax to it you could, as I said "not practical" but I have, at a field day site, ran the ends of the antenna down to the Match Box sitting on the picnic table and it works fine. It was some what like a large rabbit ear system. HIHI, At any rate if you can use 120 ft of feed line down to the Match Box it will work very well and it is usable on 160 meters as well if you wanted to construct a home brewed high Z tuner for it because the Match doesn't do 160 meters. Your lengths of one ant leg + feed line, are summing to about 180 ft which is .75 wave lengths with a low Z at the feed point and Johnson Match Box's won't like that. There are other tuners that are made for low Z loads that will work with it. For high Z, your shortest lengths need to sum out at .5 wave length. (One leg of ant + down line length on 75 meters this is 120 ft.). After you have decided on the antenna and feed line length you can add feed line at a rate of about .5 wave lengths at a time (again 120 ft on 75 meters). These lengths are not real critical as the tuner will compensate as long as you don't get more than a tenth of a wave length off and maintain a balance. If you start getting close to the .75 wavelength or 180 ft on the sum, then you will have trouble on 80 meters Now as you go higher in frequency (40 meters or 20 meters) the Match Box can handle lower and lower impedances but on 80 meters it tends to be a little persnickety due to the limitations of the capacitors. At the bottom of this web page (address below) you will see some other stuff similar to what I been saying here. http://www.qsl.net/wa5bxo/swr/swr.htm Hope this helps! Good Luck and keep up the experimenting. Let us know what you come up with. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of uvcm inc. Sent: Friday, April 14, 2006 10:48 AM To: AMRadio@mailman.qth.net Cc: [EMAIL PROTECTED] Subject: [AMRadio] wanted antenna analyzer Any other ideas about matching my extended zepp to 75 meters, Tried changing feed line length, added 300 to .001 caps, changed ant length >From 135 feet to 110 feet on each side, changed from 120 feet to 150 feet ladder line, Match is 3:1 after Johnson Kw1 matchbox Thanks for the help, Brad KB7FQR [EMAIL PROTECTED]
RE: [AMRadio] wanted antenna analyzer
Brad the sum of one ant leg and the feed line needs to be about 120 ft or 240 ft so as to come out with a high Z for the Johnson match box. Your lengths or come out with a low Z at the feed point and Johnson Match Box's don't like that. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of uvcm inc. Sent: Friday, April 14, 2006 10:48 AM To: AMRadio@mailman.qth.net Cc: [EMAIL PROTECTED] Subject: [AMRadio] wanted antenna analyzer Wanted 1. Antenna Analyzer something like the MFJ or other brand or better? for tuning antennas and tanks in transmitters 2. 6 8008 rectifiers 3. Any other ideas about matching my extended zepp to 75 meters, tried changing feed line length, added 300 to .001 caps, changed ant length from 135 feet to 110 feet on each side, changed from 120 feet to 150 feet ladder line, Match is 3:1 after Johnson Kw1 matchbox 4. Docs for RCA BTA 5F transmitter Thanks for the help, Brad KB7FQR [EMAIL PROTECTED] __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] FW: Wanted transformer Gates BC 1 G
I chose 500 ohms because I could calculate the change in my head. 450 or 600 would wouk as well. A 1/4 wave length for 80 meters is 60 ft. Any 1/4 wave transmission line attached to a load that is greater than the characteristic Z of the line will transform the Z that as seen by the source to a lower value than the load. Depending on the SWR represendted on the the 1/4 wave line. John, Wa5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of uvcm inc. Sent: Wednesday, April 12, 2006 11:47 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] FW: Wanted transformer Gates BC 1 G I am running balanced line now, I changed the length of the feed line and the ant, minor change Thanks for the info -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Coleman ARS WA5BXO Sent: Wednesday, April 12, 2006 9:09 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] FW: Wanted transformer Gates BC 1 G 1/4 wave length of 500 Ohm bal line will transform it to 250 ohms. John, WA5BXO -Original Message- From: uvcm inc. [mailto:[EMAIL PROTECTED] Sent: Wednesday, April 12, 2006 3:27 PM To: 'AMRadio@mailman.qth.net' Subject: Wanted transformer Gates BC 1 G How to lower the impendence on a double extended zepp ant from 1500 to less than 1000 ohms so my matchbox will work Brad KB7FQR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] FW: Wanted transformer Gates BC 1 G
1/4 wave length of 500 Ohm bal line will transform it to 250 ohms. John, WA5BXO -Original Message- From: uvcm inc. [mailto:[EMAIL PROTECTED] Sent: Wednesday, April 12, 2006 3:27 PM To: 'AMRadio@mailman.qth.net' Subject: Wanted transformer Gates BC 1 G How to lower the impendence on a double extended zepp ant from 1500 to less than 1000 ohms so my matchbox will work Brad KB7FQR
RE: [AMRadio] Re: Triode connecting 803's for a Modulator
I was thinking that I had read an article published by RCA explaining that the series grid resistor on 807/1625s, 20K as I recall, was placed in circuit for linearity reasons. It was having something to do with a dip or a peak in transconductance mid way in the drive. The solution was simple but it did not come to the engineers right away. Does anyone else remember the article or am I just imagining it, age you know does funny things? Of course it would protect the grid as well but I was thinking it was mainly for linearity. John, WA5BXO -Original Message- On Behalf Of ne1s Sent: Monday, April 10, 2006 12:04 PM Subject: [AMRadio] Re: Triode connecting 803's for a Modulator Elaborating on Don's comment, the reason this is done with the triode-connected 807 is that if the control & screen grids were simply tied together, the control grids would be exceeding their maximum dissapation before the screens could be driven hard enough to provide reasonable output. We don't want to vaporize the control grids now, do we :>) I suspect this would hold true for other tetrodes & pentodes in a triode connection.
RE: [AMRadio] Hint for shielded audio cable
I am speaking of high gain audio chassis here Bob. A ground loop can create all kinds of hum in audio circuitry and you will never get it right until you get rid of all ground loops especially if a power XFMR, heater XFMR or power choke is on the same chassis. These are not transmission lines for moving power. An example would be, to use these lines to connect a microphone gain control in between preamp stages. You could have three lines wrapped by a forth. A orange wire that connects between the plate output coupling capacitor to the top side of a gain control and a green wire that connects from the wiper of the control to the grid of the next stage. The third wire lets say brown, goes from the bottom side of the control to the ground buss. (See "ground buss" in the next paragraph) The three wire group is wrapped with a blue wire which is connected to the ground buss as well but is not connected at the control end. If the line is relatively short then it is OK to use the wrap wire shield as the ground for the control. It is also OK to do this if it is a true coaxial cable and not a wrap shield. If the wrap shield is used then it is best to run a separate wire for the ground on the control else you will find a RF circuit present in you audio circuitry. The separate ground wire is run inside the wrap rather than outside strictly for appearance. It's neater that way. RF circuitry is entirely different. I prefer to ground ever thing with real short wires to a single point near the socket of the RF stage. As for the heaters, one must consider the type of RF circuit. If it is a common cathode circuit where the cathode is directly grounded then nearly any type of heater wiring is OK and RF bypassing is better. If it is a cathode follower or grounded grid circuit then filament chokes should be used even with an indirectly heated cathode. The filament chokes should be very close to the heater connection and should be bypassed on the side that is not connected to the heaters so as to leave the RF on the heater. In RF output circuits with directly heated cathodes and common cathode circuit the filament XFMR for the tube or tubes should be very close to the tubes underside and heavily bypassed. The primary of the filament transformer should be RF choked and bypassed. If an RF chassis is a complete self contained rig, and has an analog modulator and microphone preamp built into it, then the modulator preamp circuitry should be on a separate sub assembly which is mounted via insulation and has only one ground connection to it. Inside the audio sub assembly there should be a ground buss which is connected to the sub assembly chassis at only one place. I generally will use some bare #12 wire and bend it so as to make small bridges across several insulated terminals spanning the bulk of the underside of the sub assembly. If I need a ground point such as a cathode resistor or grid leak resistor or one end of a shielded cable then I use the buss for the ground connection. In most preamp sub assemblies the single ground is at the microphone input. This way the microphone connector is mounted directly on the chassis sub assembly. The audio sub assembly is then mounted in such a way as to insure that its only ground is near or surrounding the microphone connection. In some cases it is necessary to make the ground point somewhere else. When this is the case the microphone connector should not be mounted on the chassis but on some insulating material and the ground connection for it should be made to the ground buss. To be safe, it is best to rectify and filter and resistor limit the 6.3 volt AC for the heaters of the audio preamps. Do this all outside of the audio preamp sub assembly. Then ground one side of the heaters to the ground buss. Although I have had good luck with a balanced AC and a filament hum bucking control it is just easier to do the DC filaments for a few tubes in the high gain preamps. I can't believe I typed up all the stuff!! John, WA5BXO
RE: [AMRadio] Hint for shielded audio cable
Don't know about the capacitance Jim. I'll need to measure it. A few inches haven't made a lot of difference in the high end of the audio spectrum though, and most of my circuits terminate in 100 K ohms or less. I was trying to think of a need for a terminated delay line type thing where as the inside wire is grounded and the outside wrap is the hot wire. I just don't have a need for it. HIHI CU, John, WA5BXO
RE: [AMRadio] : BC 610 needing POWER 220VAC
I really have no idea if it is wired for 110 or 220. I know that the Plate XFMR is 110VAC and if it were me I would wire a separate primary circuit for the plate XFMR. Just for the load balance. If the filaments and low voltage stuff is all run from side A of a 220 circuit and the plate XFMR from side B then it is feasible that the filaments and low voltage supplies would be more stable. And the pilot lamps would not dim as much. That is important when you're trying to write in the log while talking on the air by the light of pilot lamps only, HIHI. I told my wife I was going to get two 20 year olds to replace her and she told me I was not wired for 220. I'm gonna go disinfect some ice cubes. John, WA5BXO
[AMRadio] modulator tubes
I once used a pair of 4cx300 for modulators (weird tube but they were free). I remember them having the capability of working into low Z loads in AB1 operation. That is why I wanted to try them. I had a 1:1 modulation XFMR and was running 2000 volts at 400ma with a pair of 813s in the final so the modulators were going to see 5000 ohms. I remember now! I used 4 (not a pair) of the 4cx300s to get the current swing I needed. Obviously I had plenty of audio. I remember now that in experimenting, I had to wind small bare wire, weaved back and forth around the tube's funny little toes that stuck out side ways, and I brought the wires down to an octal base of an old tube such as 6SN7s (wished I had not busted all those tubes up). I then immersed the tubes upside down in cups of water and hooked it all up in place of the old 805s. I remember now that I had to get screen supply voltage from something but I don't remember, oh yea, the final 813s used a separate screen supply and a choke in the screen circuit so I used the same supply for the modulators. Boy did I have wire running all over hells half acre. At any rate the 4cx300s biased off nicely and ran for a few minuets at idle. I shut off the power and felt of the water and it was barely warm. So I fire it back up and whispered in the microphone. It had very pretty audio on the scope. So I said FOOOuur in the mike and the water in the cups instantly went to a boil!!! It's a wonder the bubbles and steam didn't cause an arc to the screen connection that was just above it. I hit the plate switch off and all was OK. I did eventually build a modulator using those tubes and a little SS speech amp to drive them. But I never had the right sockets. I continued to use the octal lash up and suspended the tubes on a Plexiglas supports which air blew threw from the pressurized chassis. The story might have been funnier if something bad had happened but thankfully it didn't. I did contemplate a special coffee maker / modulator but was a little afraid. A shake of the head made that idea go away pretty quick. I eventually went to four 813s for modulators for the same reason. Not that two would not give me enough audio but that the modulation XFMR I had didn't have enough ratio. So the four tubes worked into the lower Z really well. John, WA5BXO
RE: [AMRadio] Modulator design needed
Are you using the stock driver circuit with the driver XFMR on the 32V3? John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Sunday, March 26, 2006 8:42 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Modulator design needed I have KT88's as modulators in my 32V3, regulated screens (VR tubes), and don't have any problems. I have feedback from the sec of the mod transformer to a stage before the phase splitter, and had to chop off the high frequencies because of the phase shift in the mod iron. I don't have any fancy bypass stuff, and no instability up to 800 volts on them. I always thought if you were going to amplify audio, you should try to use low distortion tubes made for audio if you could. I like triodes, or AB1 using low distortion tubes. Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of John > Coleman ARS WA5BXO > Sent: Sunday, March 26, 2006 9:03 PM > To: 'Discussion of AM Radio' > Subject: RE: [AMRadio] Modulator design needed > > I haven't actually built much in the way of audio with 6146 however > OTIS, K5SWK, has done a lot with the tube I am sure it was > all standard > tetrode connections. He contends that the screen supply needs to be > well regulated and the control grid leak resistor, if AB1, needs to be > kept low, in the 100K or less region. He says that the circuits are > prone to RF oscillation and need carbon resistors in series with the > control grid and plates. I've seen him attach a wire to a plate and > play with low capacitance gimmick feed back to and opposite > grid. It's > sort of neutralizing, although sometimes, depending on the circuit > layout, the gimmick needs to come back to its on grid. It's > a trial and > error thing. I think keeping the grid resistors low helps in this as > well. At any rate he has built some awesome sounding amplifiers with > 6146s at 600V and up where stability is really important. > > I am currently assembling a 50 watt per channel KT88 amp. Two per > channel with a 5000 ohm plate load XFMR. Plate supply is 450V and the > regulated screen supply at 320 volts. Standard tetrode > connection. Also > am using a little inverse feed back from the 16 ohm out back to the > cathode resistor of the triode before the phase splitter. I'm having > some stability trouble with or with out the feedback. At high input > levels I was getting a HF parasitic burp and I am currently > trying some > of Otis's tricks. I think I've about got it settled down. I think > bypassing the screens and filaments with .01 ceramics has > made the most > deference. I'd found in the past that the filament lines can be the > transport path for RF parasitic oscillations and that electrolytic > capacitors don't bypass HF very good. > > John, WA5BXO > > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski > Sent: Sunday, March 26, 2006 7:09 PM > To: 'Mike Dorworth, K4XM'; 'Discussion of AM Radio' > Subject: RE: [AMRadio] Modulator design needed > > I never had much luck getting 6146's sounding good as modulators, > I think it takes a fair amount of effort. > > > The KT88 or KT90 on the other hand works great in AB1. > > The KT90 is reasonable in price, and can run up to 800 volts or more, > 170 watts out I think in AB1 at low distortion. > > Brett > N2DTS > > > > > > -Original Message- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Mike > > Dorworth, K4XM > > Sent: Sunday, March 26, 2006 5:05 PM > > To: Discussion of AM Radio > > Subject: Re: [AMRadio] Modulator design needed > > > > 6146 AB-1, 500 volts, 75 watts, 600 Volts, 95 watts, 750 > > Volts, 120 > > watts.. > > > > I thought the original question was to modulate a Johnson 6N2 > > which uses a > > 5894. Usually one uses the same Plate supply for the final as > > the modulator. > > The 6146 gives way too much power for the voltage rating the > > 6N2 would use, > > 450-600 Volts. The AB-1 807 or some of the hotter 6L6 > > versions such as 6L6GC > > seem more in the same voltage line to give the power needed. > > > > The Viking II could do the whole job with a Ceramic 4 pole, > 2 position > > switch as shown in Bill Orr's 14 Edition Handbook (his First) > > It was mounted > > on the rear apron along with a 3 lug terminal strip. > > > > In the older 12t
RE: [AMRadio] Modulator design needed
I haven't actually built much in the way of audio with 6146 however OTIS, K5SWK, has done a lot with the tube I am sure it was all standard tetrode connections. He contends that the screen supply needs to be well regulated and the control grid leak resistor, if AB1, needs to be kept low, in the 100K or less region. He says that the circuits are prone to RF oscillation and need carbon resistors in series with the control grid and plates. I've seen him attach a wire to a plate and play with low capacitance gimmick feed back to and opposite grid. It's sort of neutralizing, although sometimes, depending on the circuit layout, the gimmick needs to come back to its on grid. It's a trial and error thing. I think keeping the grid resistors low helps in this as well. At any rate he has built some awesome sounding amplifiers with 6146s at 600V and up where stability is really important. I am currently assembling a 50 watt per channel KT88 amp. Two per channel with a 5000 ohm plate load XFMR. Plate supply is 450V and the regulated screen supply at 320 volts. Standard tetrode connection. Also am using a little inverse feed back from the 16 ohm out back to the cathode resistor of the triode before the phase splitter. I'm having some stability trouble with or with out the feedback. At high input levels I was getting a HF parasitic burp and I am currently trying some of Otis's tricks. I think I've about got it settled down. I think bypassing the screens and filaments with .01 ceramics has made the most deference. I'd found in the past that the filament lines can be the transport path for RF parasitic oscillations and that electrolytic capacitors don't bypass HF very good. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Sunday, March 26, 2006 7:09 PM To: 'Mike Dorworth, K4XM'; 'Discussion of AM Radio' Subject: RE: [AMRadio] Modulator design needed I never had much luck getting 6146's sounding good as modulators, I think it takes a fair amount of effort. The KT88 or KT90 on the other hand works great in AB1. The KT90 is reasonable in price, and can run up to 800 volts or more, 170 watts out I think in AB1 at low distortion. Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Mike > Dorworth, K4XM > Sent: Sunday, March 26, 2006 5:05 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Modulator design needed > > 6146 AB-1, 500 volts, 75 watts, 600 Volts, 95 watts, 750 > Volts, 120 > watts.. > > I thought the original question was to modulate a Johnson 6N2 > which uses a > 5894. Usually one uses the same Plate supply for the final as > the modulator. > The 6146 gives way too much power for the voltage rating the > 6N2 would use, > 450-600 Volts. The AB-1 807 or some of the hotter 6L6 > versions such as 6L6GC > seem more in the same voltage line to give the power needed. > > The Viking II could do the whole job with a Ceramic 4 pole, 2 position > switch as shown in Bill Orr's 14 Edition Handbook (his First) > It was mounted > on the rear apron along with a 3 lug terminal strip. > > In the older 12th Edition (Editors and Engineers) there is > shown a phase > inverter driving 6V6's and also one driving pair 813. A 6C4 > in the former > and a pair of 6SJ7's in the later case. On the AM Forum > Archives there is a > pair of 4-400's driven in AB-1 by a pair of 2E26. Google > N9FOY and click on > modulator. Circuits from 6AQ5, 6V6, 807, 6146, 813, 4-400 all > published and > none using driver transformers shows this is an OK way to go > for most any > power level. > > Mike > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb > __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Modulator design needed
Although the output tubes are 6146s the circuitry of the driver is what is in question. The older 6SN7 could be replaced with the 5697 9 pin mini or at lower voltages the 12AU7s could work. The idea of the pahse splitter is to use a triode with exactly the same resistor for both plate and cathode load resistors. Use a small value such as 2 X 22K the at the grid of the push pull long tail driver use a very high resistor such as 470K each. The common cathode resistor of the long tail makes the circuit a semi differential amplifier which compensates of discrepancies in the phase splitter. These discrepancies include different output capacitances for plate and cathode and load handling capabilities. The differential amplifier corrects a lot of the differences making the outputs closer to a true phase 180 degree difference at a single moment and across a wider frequency responds. Of course if your only want a few watts of audio you can chose modulator tubes that will allow a larger grid resistor for AB1 operation with out going into thermal grid leakage run away. 6V6s, 6L6s, etc. with the smaller tubes and less heat you can use higher grid leak resistors and come right off of the phase splitter to the grids of the output tube with out using the differential amp in between. 73, John, WA5BXO
RE: [AMRadio] Modulator design needed
Try this on for size. http://www.bonavolta.ch/hobby/en/audio/6146.htm I would recommend a balancing control in the cathode circuit of the driver stage as the common cathode resistor compensates for irregularities in the phase splitter it will also cause and improper DC offset due to a possible imbalance in the two triodes. A small 500 ohm pot placed between the two cathodes and then the cathode resistor on the wiper would be better. This type of circuit is sometimes called a long tail driver phase splitter. I think? If you need to go to AB2 and draw some grid current from the modulators, then the transistors of the SS driver circuit, can be replaced with small tetrode tubes. The RCA 1KW BC rig uses two 807s as direct coupled cathode followers to the grids of the 833 modulators. There is no reason a pair of 6AQ5s couldn't drive 811s or by the same token, a pair of 6AU6s should drive 807s or 6146s really nice. The cool thing about driving with tubes instead of transistors is the high Z input could come from a RC coupled phase splitter. The draw back is the need for a negative supply and possibly separate filament windings for the drive tubes, since there cathodes will be hot with DC and audio. Don't forget to bypass the screens to the cathodes, not to ground. None the less, it is a very nice project and would deliver very nice audio. John, WA5BXO
RE: [AMRadio] Kenwood TS-820 mod for am
Bill, There is a switch on the panel of the TS820 and for the life of me I can't think of what it was used for right now and I'm not at the shack, but its use was never found inviting so BJ, WB5PKD, and I found a use for it. You see, the TS-820 uses diode switching to move the XTAL and SSB filter reference for upper and lower SSB, as well as CW. So we decided to use the basically unused switch to do the same thing and removed the filter in one position of the switch as well as activating the control for the carrier level insertion. Putting the switch back in its normal unused position returns the 820 to normal operation as per its regular function switch. For example, we set the rigs function switch in lower SSB for 80 or 40 meters when the "unknown switch" is place in the proper position the SSB filter is bypassed, as it would be in CW, but the carrier for XMIT is not exalted, it stays put as it was for LSB (this make XERO BEATING a snap) and the CW level control becomes carrier insertion for AM. It is full AM in XMIT but there is only product detection for RCVR. I want to build a PLL detector to make the product detector lock on RCVD carrier but just haven't done it. The TS-820s normal function is to provide about 10 watts carrier to the SB200 linear (we just turn the audio level down all the way) which then drive the class C push-pull pair of 250ths which is plate modulated by four 813s push-pull parallel class AB1. But the big rig can be bypassed and the SB200 running about 75 watts AM can be put on the antenna or the TS820 running a max of 20 watts AM can also be put directly on the antenna. Receiving is generally done on the HQ145 or SP600 although there or other receivers, 4 or 6 about the place that we occasionally use. BJ and I are bad about documentation although we are getting better. We tend to fly by the seat of our pants when it comes to making changes or designing something. But if you're interested I will try to find the hen scratching we did on some stained coffee napkin and copy it for you. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bill Fondren Sent: Saturday, March 18, 2006 4:42 PM To: amradio@mailman.qth.net Subject: [AMRadio] Kenwood TS-820 mod for am Hello allFirst let me say how much I have enjoyed the recent discussion on linear amplifiers. I have a Kenwood TS-820 that I would like to modify for am for a standby transmitter. A day or two ago I remember seeing a remark about modifying a TS 820 for double sideband. I have a friend who has a 520 and used screen grid modulation for am operation. The email containing the remark seems to have been deleted. Any remarks or where to get the information would be appreciated. Bill Fondren K5PML __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Class AB and B audio XFMRS
I love this stuff! John, WA5BXO -Original Message-Not in its entirety. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bob Bruhns Sent: Thursday, March 16, 2006 10:12 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Class AB and B audio XFMRS Magnetic hysteresis is a complicating factor. When you apply a magnetic field to a magnetic material, it is partially magnetized. When you saturate it, it is strongly magnetized. When it is magnetized, it opposes the application of a reverse magnetic field, and it takes a certain reverse applied field to overcome the residual field in the material, and it takes a little more reverse applied field to reverse the residual field. This causes a timing delay in the magnetic transitions. The amount of delay depends on the applied signal level.
RE: [AMRadio] Amplifier to use with my DX-60
Alan, most all tube type linear amps are class B, or AB and can be single ended or push-pull. In RF service the tank tuning takes care of the output wave distortion making nice pretty sine waves. Linear amps are not class C because class C is really more like a switch than an amplifier. In most class C finals you can vary the input some and it will not make any difference in the output. For this reason they or good for CW and plate modulated AM. Class C finals have a characteristic of the output following the plate supply voltage up and down linearly. If the plate supply is dropped to half the RF output voltage will drop to half, and so on. For this reason the audio is inserted in the plate power supply line, hence plate modulated. As for power levels, an SB200 is only about 3DBs better than getting rid of the control carrier modulator in the DX 60 (put it in the CW position) and building an external plate modulator for it. And it will sound a lot better. It is a really cheap project too. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Alan Beck Sent: Thursday, March 16, 2006 8:34 AM To: Discussion of AM Radio Subject: [AMRadio] Amplifier to use with my DX-60 I would like to use a cheap am with my DX-60. An SB-200-230 seems to be a Class B amp. There for it only conducts on the positive going cycle. I don't mean to sound silly, but someone told me I could run this in SSB Mode using AM input from my DX-60, I run 100 Watts carrier for 400 Watts peak, now that makes sense. What does not make sense is how do I get the other side of the wave form The Tank??? I guess the tank. I really need to go cheap on this project. I know, you guys will probably say "go big or go home". Best 73 Alan
RE: [AMRadio] Class AB and B audio XFMRS
This is what I have so for guys, and Larry I quoted you as well hope it is OK http://wa5bxo.shacknet.nu/XFMR_losses/audio_transformers1.htm Now Bacon, You know I can't spell. If any thing is right on that page it is because of built in spell checking. I hate getting old I'm all upside down, my nose is runnin' and my feet's are smellin' John, WA5BXO
RE: [AMRadio] Class AB and B audio XFMRS
Very interest Jim: On magnetic bucking: I guess just a few turns of some heavy wire would suffice and the bucking current could be many amps to compensate for the fewer turns. But the DC CCSource would need to be fee of HUM or any variations else it would modulate the secondary with a step up. Perhaps more turns in the bucking coil would be better. It is an interesting concept though. On LOW freq distortion in the output XFMR: I found it interesting, how the cross over distortion reappeared (in my PP KT88s CLASS AB1) amp as the Frequency of the driving signal when down (talking below 20 CPS). It shows the need to limit the low end of the pass band in the preamps to a value that will coincide with the pass band ability of the output XFMR. Accidentally hitting the grids with too low of a frequency while trying to pass high frequencies at the same time caused not only distortion in the lows but it modulated the higher frequencies with the distortion. And it really sounds bad! Limiting the low frequency pass band in the preamps really cleaned up the audio. You might ask what low frequencies we are talking about. It's the 4 - 10 CPS stuff that comes from turn table rumble. On class A XFRMerless solid state audio the speakers just moved with the rumble (yes, a total waste of power and could damage the speakers). But with the tube equipment it created quite a stink with intermodulation right in the output XFMR. I am sure that some of the bad stuff we hear some times on the air is due to incomplete modifications where the preamps and drivers of the audio equipment have been modified to pass 20 to 30 CPS but the modulation XFMR circuitry can not pass below 100 with out intermodulation occurring in the XFMR due to core saturation and/or cross over distortion. John, WA5BXO
RE: [AMRadio] 1930's Old Buzzard Open Rack TransmitterFinallySeestheAirwaves! (Long)
A pair of 812As should get you about max 360 watts out with 65 watt PD in intermittent service (CW not AM). I can't see the T55 doing better with a lower plate dissipation limit. For those that don't readily have the specs-- 812A Class C Plate Modulated (CCS) 45 watt PD Plate Voltage . 1250 VGrid No. 1 Voltage -115 VGrid No. 1 Current 35 mA Plate Current . 140 mA Driving Power . 7.6 W Power Output (approx) . 130 W Grid leak resistor 3286 ohms That is 175 watts input on a single tube with 130 watts output. Plate dissipation in this service is only 45 watts of the 65 watts rated, so this should be a continuous duty service. Push pull specs for Class C should yield about 350 Watts input and 230 watts output, an efficiency of 75 percent. Grid current and plate current doubles for push pull service as does output and driving power. Grid leak resistance should be one half or about 1643 ohms The two most common cause of poor efficiency is improper drive/bias and improper Q in plate tank circuit Ratio of (C to L). These tubes are easy to drive, rugged, good efficiency, modulation characteristics fantastic, low filament power, uses common components for construction. In my opinion this service and tube line up is the best choice for a conservatively rated light weight legal rig. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Tuesday, February 21, 2006 9:44 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] 1930's Old Buzzard Open Rack TransmitterFinallySeestheAirwaves! (Long) The T55 has 55 watts of plate dis, and gives 170 watts out? The 812A has 65 watts of plate dis and gives 130 to 150 watts out? I get about 275 watts out at 1500 volts, no color on the plates, maybe I should try the T55's, they will give me 340 watts out? I never even plugged the T55's in or tested them. Filaments are no problem, I have a panel mount variac to adjust the voltage between 0 and 12 volts. I did try a set of 572b tubes, but they seem to work hard and not give a lot more power output. Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of crawfish > Sent: Tuesday, February 21, 2006 10:07 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] 1930's Old Buzzard Open Rack > Transmitter FinallySeestheAirwaves! (Long) > > My 1937 Jone Radio handbook says that a T-55 has 55 watt > plate dissipation, > typical 1500 vdc plate voltage with -180 vdc grid bias, max. > Ip is 150 mA, > max. Ig is 30 mA.10 watts RF in, 170 watts RF out for 225 > in.7.5 VAC @3.25 > on filament. The 811A is 65 watts plate dissipation, the > difference in the > 811A and the 812 is that the 811A is zero bias and the 812A > needs -110 vdc > bias. Power out of the 811/812 is 130 to 150 watts. > 811A/812A info from 1970 ARRL Handbook. > Joe W4AAB > - Original Message - > From: "John E. Coleman (ARS WA5BXO)" <[EMAIL PROTECTED]> > To: "'Discussion of AM Radio'" > Sent: Tuesday, February 21, 2006 8:33 PM > Subject: RE: [AMRadio] 1930's Old Buzzard Open Rack > Transmitter Finally > SeestheAirwaves! (Long) > > > CONGRADULATIONS A JOB WELL DONE! > I really like the choice of tubes. I don't know what a T55 is but > probably one of the special Taylor triodes with 55 watts > plate dissipation. > Probably not a lot different than the 812s but I know that > the 812s are very > good tubes to use in a class C plate modulated rig especially > if used with > 100% grid leak bias or the configuration that Don, K4KYV, > uses where there > is a safety bias supplied thru a diode and the diode becomes > reversed biased > when RF drive causes grid leak bias. The 100% Grid leak bias > DOES make a > difference in the modulation characteristics of the rig. > John, WA5BXO > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of ne1s > Sent: Tuesday, February 21, 2006 2:27 PM > To: AM Radio Reflector; [EMAIL PROTECTED]; > [EMAIL PROTECTED] > Subject: [AMRadio] 1930's Old Buzzard Open Rack Transmitter > Finally Sees > theAirwaves! (Long) > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net
RE: [AMRadio] Re: AM Transmitter Advice??
OK BOB! You got my attention. Explain more. I hope I'm not a sucker here. I have seen and extremely low mu amplifier circuit (common cathode) made by reverse biasing the plate of a triode and forward biasing the grid where output is taken from the grid and input is on the plate. So I know that weird stuff does exist. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bob Deuel Sent: Thursday, February 16, 2006 6:05 PM To: 'Discussion of AM Radio' Subject: [AMRadio] Re: AM Transmitter Advice?? Hello Larry and all: Larry's tongue in cheek comment employing 866's as a linear amplifier tube prompted me to contribute the following: Certain full-wave rectifiers can be configured to amplify or oscillate. I have built audio, Hartley and Simpson oscillators using only 6AX5GT's full-wave rectifiers as the sole active device. These were displayed at 2004 Mid-Atlantic Antique Radio Club Meet and actually won a Blue Ribbon. Late last year I built an AM transmitter consisting of a Hartley oscillator modulated by an AM modulator using only 6AX5GT full-wave rectifier tubes as the active devices. No solid-state magic, just simple full-wave rectifiers. The basic concept is that of the Heintz and Kaufman gridless Gammatron circuits. The transmitter was set up for the broadcast band and works fine. It has been publicly demonstrated a couple times now and a write up including the circuit was published in the February, 2006 issue of the "Tube Collector" magazine which is the bi-monthly magazine published by the Tube Collectors Association, Inc. It is fun to make full-wave rectifiers do more than just rectify. Bob, K2GLO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ne1s Sent: Thursday, February 16, 2006 10:36 AM To: Discussion of AM Radio Subject: [AMRadio] Re: AM Transmitter Advice?? Donald Chester writes: > >> Assuming one is going to build a linear, and so putting aside other >> issues >> such as linear vs plate modulation, why do you think it makes a >> difference >> what tube is used? Are you referring to running a linear at greater than >> legal limit?. > > Well, go ahead and try building a legal limit linear that runs a pair of > 807's in the final. > Yeah, or a pair of 866As Sorry (the devil made me do it). 73, -Larry/NE1S __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Push-pull Triode HF PA layout question
Construction of a push pull circuit is a real difficult project if started wrong. It has been my experience to find that the plate tank and grid tank do need to be as far apart as possible if plug in coils are to be used and they need to be at right angles to each other. Some folks choose to use a band switched coil arrangement where the grid coils and switch assembly can be in a completely shielded case of its own or below the chassis that is sealed up for RF. I have actually used a Johnson Match Box 500 as a grid drive circuit years ago. It sat on the desk and I used that 300 ohm shielded cable that Radio Shack, sold years ago, to feed it to the grids. I put two RF chokes in the Match Box to attach the grid leak resistor and bias supply to. It worked quit well. I remember I could adjust the length of the twin lead cable to get better results on some of the higher frequency bands. I prefer the switched coil assembly in a shielded box and mounted under the chassis myself. You may find more ideas at http://wa5bxo.shacknet.nu/wa5bxo.qsl/pptriodes/pptriodes.htm Good Luck John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ne1s Sent: Monday, February 06, 2006 2:31 PM To: AM Radio Reflector; [EMAIL PROTECTED] Subject: [AMRadio] Push-pull Triode HF PA layout question Hello all, I humbly request the experience-based advice of this esteemed group. Background: I am working on a project, part of which involves completion of 1930s Push-pull trode PA deck for 80M - 10M. Notice I said "completion," not "construction." This deck already has the plate tank components, tube sockets, and neutralizing capacitors mounted on a beautifull black-wrinkle chassis & panel. The axis bisecting the holes for the tubes is parallel to the front panel, the plate tank air variable (split stator) is perpendicular to the front panel, and the plate tank coil (plug-in jack-bar style - actually I'll be using BC-610 coils, link-coupled to the antenna) is centered directly behind the plate tank capacitor, with its axis parallel to the front panel. What this deck lacks is a grid tank circuit, which I need to add. The tubes will be 812s or T-55s, and will be plate-modulated for 250 - 300W output. Question: What is the worse sin: lack of physical symmetry, or proximity of the gazinta to the gizouta? It seems that I'll have to compromize one or the other in adding the grid tank circuit, based on the present layout. The grid tank will be link-coupled to the exciter. Thanks for your assistance, -Larry/NE1S __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] 32V-2 speech amp question
I have not driven it externally before Craig but have some experience with the circuitry and the driver XFMR is a weak link in the circuit the XFMR barely has enough iron and coupling coefficiency in it to pass the low frequencies that the rig is designed for. As a matter of fact if the cathode resistor of the driver stage drops in resistance, as they or known to do with heat, the driver plate current will quickly saturate the driver XFMR causing the bass frequencies to look like a trapezoid instead of sine wave. If you were going to go with and outboard amplifier I would include a better driver XFMR as part of the external circuit and go to the grids directly. John Coleman -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Craig Roberts Sent: Saturday, January 21, 2006 10:19 PM To: Discussion of AM Radio Subject: [AMRadio] 32V-2 speech amp question Has anyone tried driving the mod input transformer of the 32V-2 (or V-3) directly with an outboard mic preamp? If so, what were the results, please? Many thanks and 73, Craig W3CRR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Web page appears in opposition to RM-11306
Gary, you are 100% technically correct here on this and I will admit to being a little arrogant about the statements. I guess this whole thing is just rubbing me the wrong way. I really am getting to old to put up with changes any more. And boy, nothing is sacred, they even change the names of some streets twice in this mans life time. Once was enough to make me curse and hate lawyers and politicians. HIHI CUL, John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gary Schafer Sent: Tuesday, January 17, 2006 8:09 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Web page appears in opposition to RM-11306 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John E. Coleman (ARS WA5BXO) Sent: Tuesday, January 17, 2006 5:11 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] Web page appears in opposition to RM-11306 As for measure of power, it was 1KW DC input MAX as measured by the product of plate voltage and plate current meters with a time constants of .25 sec. As long as the product of the two meters did not exceed 1KW then you were legal. Typically, when these conditions were properly monitored, the max output obtainable by a legal SSB station was about 1500 watts PEP. I jokingly say, "the manufactures of SSB desktop equipment were sore about the AM stations that could get 750 to 800 watts of carrier and modulate it to 3000 watts PEP output (SINE WAVE) with out their plate current moving". Not joking, by the use of natural asymmetrical audio I was able to get about 7 KW PEP output with no plate current increase. Also there seemed to be a lot of dummying down of folks about that time. So, 1500 watts PEP output is about the same as ever for a SSB station but was a kick in the teeth for big iron home brewers of AM stations. John, WA5BXO 1500 watts PEP output is not the same as ever for SSB. The SSB guys lost right along with the AM guys on the maximum power level. At 1 kw average, or indicated on the plate meter, average output on SSB is around 600 watts. The PEP level of that much power will range anywhere from 3000 to 5000 watts. Just the same as it will with AM less of course the difference in amplifier efficiency. Watch the output power meter on your SSB rig when it is operated at 100 watts PEP output. The average output (on an average reading wattmeter) will indicate only around 15 to 20 watts unless you are using lots of compression or ALC. When not hitting any ALC the average will be quite low. However in years bygone most people thought that PEP was automatically twice what average power was. That is true with a two tone test signal but of course not with voice. Most amplifiers in those days were not built to deliver much more than 2 kw pep output so most did not realize what they had lost. A lot of folks thought they gained power with the new rules as now you could run around 3000 watts input indicated on the plate meter (in CW) for 1500 watts output. Many were confused about what PEP really was, including the manufacturers if you look at some of the old spec sheets on SSB gear. 73 Gary K4FMX __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Web page appears in opposition to RM-11306
Also Jim, you may not need a BFO for CW in the phone band, HIHI. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of W1EOF Sent: Monday, January 16, 2006 10:44 PM To: Discussion of AM Radio Subject: RE: [AMRadio] Web page appears in opposition to RM-11306 Jim - I am a CW op about 99% of the time. Yet I have to be honest and say I agree with you on 80M. Other than during a contest, we can give up some space to phone operation. I'd say to be fair a starting point would be 3700. Maybe 3650. However I disagree on 40M and 20M, especially 40M. Almost every night that little sliver of usable band is filled with CW signals. If you are not an Extra, as a CW op your version of 40M is 7026 - 7046 most night. 20kc. Not a heck of lot of room ro stretch out at all. I'd love to be able to get that @*&[EMAIL PROTECTED] broadcast out of 40M. Holy moly if we had that whole band unmolested it would be a GREAT place to play. Just my feelings as a CW op. 73, Mark W1EOF > -Original Message- > From: Jim Wilhite [mailto:[EMAIL PROTECTED] > Sent: Monday, January 16, 2006 10:21 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Web page appears in opposition to RM-11306 > hope, but the > fact remains, more space is needed for phone operation and the > lower half of > 80, 40,and 20 are under utilized. > > 73 Jim > W5JO -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.18/230 - Release Date: 1/14/06 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] Web page appears in opposition to RM-11306
Just get on 40 meters and consider it a challenge to communicate over the broadcasting stations. You have as mush right to be there as them. Start up talking to you neighbor running as much as you can to a low angle radiator. Be sure your not zero beat. Don't think for a minute that the heterodyne you cause won't be heard over seas. That should start an inquiry. Then again, they would probably just take 40 meters away from us. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of W1EOF Sent: Monday, January 16, 2006 10:44 PM To: Discussion of AM Radio Subject: RE: [AMRadio] Web page appears in opposition to RM-11306 Jim - I am a CW op about 99% of the time. Yet I have to be honest and say I agree with you on 80M. Other than during a contest, we can give up some space to phone operation. I'd say to be fair a starting point would be 3700. Maybe 3650. However I disagree on 40M and 20M, especially 40M. Almost every night that little sliver of usable band is filled with CW signals. If you are not an Extra, as a CW op your version of 40M is 7026 - 7046 most night. 20kc. Not a heck of lot of room ro stretch out at all. I'd love to be able to get that @*&[EMAIL PROTECTED] broadcast out of 40M. Holy moly if we had that whole band unmolested it would be a GREAT place to play. Just my feelings as a CW op. 73, Mark W1EOF > -Original Message- > From: Jim Wilhite [mailto:[EMAIL PROTECTED] > Sent: Monday, January 16, 2006 10:21 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Web page appears in opposition to RM-11306 > hope, but the > fact remains, more space is needed for phone operation and the > lower half of > 80, 40,and 20 are under utilized. > > 73 Jim > W5JO -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.18/230 - Release Date: 1/14/06 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] I'm not an antenna expert
I would be curious as to what the fundamental resonance frequency is and what the high impedance and low impedance actually is at the feed point of the antenna without balanced line. If the feed point at the transmitter end of the line is too low, add or subtract some feed line. You can also add and subtract line from the opposite side of the antenna. You mentioned earlier about opening up the opposite end. This could be a good experiment. And also consider capacitance or inductance added where you make the cut or adding transmission line at that point with and open or closed end going nowhere except to a stick to hold it up off of the ground. It doesn't take a mathematical antenna expert to experiment You only need some extra wire. Fun Stuff John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Lawson Sent: Wednesday, January 11, 2006 10:44 AM To: amradio@mailman.qth.net Cc: [EMAIL PROTECTED] Subject: [AMRadio] I'm not an antenna expert I don't even play one on TeeVee... So, in advance of a lot of EZNec work (and I don't have the experience with that program to derive much 'good' out of it right now) - I'd like to ask what may seem to be a rather obvious HF antenna question. Due to the usual reasons - my HF antenna is a loop suspended from my backyard fence - approx 430' total, closed loop, 5' off the ground, fed by 450 ohm ladder line back into the shack, using an Ameritron ATR-15 tuner to match the system to my Valiant. The tuner and transmitter are bonded to a very heavy ground system via an 8' stake less than 3' from the gear. There is no ground system under the antenna, other than that which Nature provided - and with the current winter conditions, the ground is rather wet and conductive. This antenna system exhibits the following SWR: 160M - 1.3:1 80M - 1.1:1 40M - +3:1 20M - 2:1 15M - +3:1 10M - +3:1 The tuner capacitors end up being all-the-way-meshed on the 'misbehaving' bands - not so on 160, 80, and 20. So I'll see Y'all on 3880 and just fergit the rest. ;} No but seriously folks: obviously the feedpoint resistance is outside the tuner's ability to cope with it at various frequencies. I'm thinking the first unscientific experiment might be to go to the opposite side of the loop from the feedpoint and cut it into a big horizontal bent dipole - mainly because that will take about 45 seconds to accomplish - one of the benefits of having one's entire antenna at ahoulder-height. But I'd like to get some other opinions - I know there's an electrical Pattern here from the info - and I have some other ideas based on that. And no, I can't put up a "real antenna" so I'm pretty much comiited to making this one work as well as I can. Until I move the QTH to somewhere with a few acres and room for Lots of Wire. Cheers John KB6SCO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] R-388 PTO info needed
I have had one in and out of a 32V3 XMTR several times repairing flood damage. It's not that hard. The oscillator circuit is not that complicated. I don't know the same about the 75A4 PTO removal, but if that is not to bad, then just fined the open resistor or the shorted capacitor and replace it. Be sure to check the DC and filament lines going into it first. Mine was filled with mud and had a stuck slug, which I broke trying to free it up. But I got it working. Of course the calibration is way off because of the broken slug, but that is not going to happen in your case. Yours was not full of mud for 2 - 3 years. John WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Lawson Sent: Sunday, December 25, 2005 3:47 PM To: amradio@mailman.qth.net Subject: [AMRadio] R-388 PTO info needed Further to my Xmas Eve Scrooge Radio Post - I have discovered that no signals of any kind appear on the PTO output cable when isolated from the mixer tube, and injecting the correct frequency into that pin of the mixer (from my bench oscillator) restores the radio to operation. So, of course, the PTO has quit, and the tubes (AFAIK) are good - but next I'll replace them with a couple that test out at better than 70% Gm - somehow I think that's not going to be the Problem. If anyone within the sound of my keyboard has any experience actually repairing this series of PTO - it's a Collins 70E-15 ser. M1751 - I'm trying to guage whether I should spend the time to dredge it out and fix it - or (since the front panel needs to be refinished) I would be better served by just bundling it off to someone and letting an expert refurb the radio. I do plan to keep it, it's my Fave Reciever - for Ham and SWL - Also: if you have a quote to perform the above, lemme know ASAP - I'm 'motivated' as they say in Real Estate. Cheers and Best of the Season! John KB6SCO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] List Server - PLEASE READ - VERY IMPORTANT
In the meantime here is the PST file maybe some else can deal with it. It is a PST with just the OLDAMRADIO folder from 8/8/2000 to 12/31/2001 http://wa5bxo.shacknet.nu/oldAMradioPST.zip John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John E. Coleman (ARS WA5BXO) Sent: Friday, December 16, 2005 6:36 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] List Server - PLEASE READ - VERY IMPORTANT I just realize that this export of the old stuff doesn't have dates. That's weird! Can anyone explain why that would be? It has dates when viewed with outlook while it is part of a PST, but I can't seem to figure out how to get the date field to export to a spread sheet or a DB file. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John E. Coleman (ARS WA5BXO) Sent: Friday, December 16, 2005 12:42 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] List Server - PLEASE READ - VERY IMPORTANT Here you go Brian. I included December. Download from here. http://wa5bxo.shacknet.nu/oldAMradio.zip DBF and MDB John WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brian Sherrod Sent: Friday, December 16, 2005 7:42 AM To: amradio@mailman.qth.net Subject: RE: [AMRadio] List Server - PLEASE READ - VERY IMPORTANT John, Geoff, I've already downloaded the entire archive from qth.net. About 8100 messages, I think. That covers Dec. 2001 thru now. John, is there anyway you can archive just those prior to Dec. 2001 and put them into a dBase format? I no longer have anything prior to Dec 2001. I may end up doing some mSQL database type script to ultimately access the data online using Perl or PHP... Don't know just yet, as it will also depend on my time, and that's something I've not had much of lately. What I have right now from the qth.net archive is already formated to HTML with Pipermail. I may have to convert the html on these into an mSQL database later. Thanks, Brian > Date: Thu, 15 Dec 2005 21:29:10 -0600 > From: "John Coleman ARS WA5BXO" <[EMAIL PROTECTED]> > Subject: RE: [AMRadio] List Server - PLEASE READ - VERY IMPORTANT > To: "'Discussion of AM Radio'" > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset="us-ascii" > > My outlook folder for "AMRadio" shows over 10500 entries and goes back > to 8/8/2000 I can export it to > > 1) a dbase type file, > 2) a PST for Outlook, > 3) or a ASCI delimited file. > > And then zip it up and post it on my server. > Which would you like? > > John Coleman > WA5BXO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] List Server - PLEASE READ - VERY IMPORTANT
My outlook folder for "AMRadio" shows over 10500 entries and goes back to 8/8/2000 I can export it to 1) a dbase type file, 2) a PST for Outlook, 3) or a ASCI delimited file. And then zip it up and post it on my server. Which would you like? John Coleman WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of W5OMR/Geoff Sent: Thursday, December 15, 2005 7:51 PM To: Discussion of AM Radio Subject: Re: [AMRadio] List Server - PLEASE READ - VERY IMPORTANT Brian Sherrod wrote: >The other reason I wanted to do this was to have more control over the list archives. >I will now be able to setup a "search engine" for all members that will allow you to >find keywords within the archives. In the meantime, I have also been downloading ALL >the old archive off qth.net which go back to Dec. of 2002. There are over 8050 >archived posts many of which are extremely valuable from a technical standpoint. > >As soon as I have the search engine setup, I will post the address to this. > I'm looking at the total number of posts that I have in the AM Reflector folder in my mail client now, Brian, and I'm showing 2220. If you like, I could archive them, and give you a pretty good start on the search engine. I -think- I can access the old instance of my Windows installation, and probably come up with another year's worth of posts. (I might need John Coleman's expert advice in how to do this, but I'm sure if it can be done, he's the guy that would know how). Just trying to give back to the great AM Community. --- 73 = Best Regards, -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
RE: [AMRadio] MY new web layout
Hi Bacon I for one would really like to have a copy of all your writings. If you get them all together maybe you could email them to me in one large zip. Let me know how large it is and I will accommodate with the appropriate setting on my email server. Then, with your permission, I'll post them for all the world to see and download so everyone can benefit. Thanks John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bob Bruhns Sent: Tuesday, December 13, 2005 5:17 PM To: Discussion of AM Radio Subject: Re: [AMRadio] MY new web layout Hi John, That looks good! I have a collection of the various posts I have made over the past years, and there are a few recent ones that I need to download and save before the next board crashes, or the next site closes, etc. I should make them into a notebook and they should go into collections in various forms, along with other people's work, on various sites, so that this stuff doesn't get lost. It took forty years of study to learn all of this, and the new guys don't know about it. Bacon, WA3WDR
RE: [AMRadio] MY new web layout
It was brought to my attention that my web page was really behind and that I had left out some links to some very important stuff that Bacon had done so I have corrected it now I hope. http://www.qsl.net/wa5bxo and http://www.qsl.net/wa5bxo/amtech.html Let me know if it is all OK now. John, WA5BXO
RE: [AMRadio] Re: Need list of good AM radios to start lookingfor.
I don't know if the power supply come from the same XFMR or not but what does "10 on the knob" mean? John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Lawson Sent: Wednesday, November 16, 2005 8:02 PM To: Discussion of AM Radio Subject: Re: [AMRadio] Re: Need list of good AM radios to start lookingfor. For my Ranger / amp situation, I originally looked at doing exactly this. I have a couple of reservations - first is that the LV Supply will have to stand the additonal load over the long haul, and second that I'd really rather the mod section be running at "10 on the knob". Also, the resistor, if variable (even the 'slider' type) allows one to adjust the output as needs be - I want to run RTTY which is even more severe than AM in terms of overall duty cycle , and I want to spare my old amp (an Ameritron AL-80) as much as possible. Then again, I have the schematics for the "attenuator" as Johnson called it - to go between the Ranger output and linear input. And of course there a lots of topologies that will accomplish the task of lowering the output of a tetrode or beam-power RF section without upsetting the relative current balances. Mebbe I oughta should by a junker Ranger... Just In Case... ;} Cheers John KB6SCO __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
RE: [AMRadio] BC-610 terminating impedance
I may have missed something here amongst all the messages and I really am not too familiar with the BC610 but I thought it had variable loading with an adjustable 3-4 turn link. If so, it should be able to load into a fairly wide range of loads. On my variable link rig I can go down to about 10 ohms load by pulling the link out to maintain the proper plate current, but with the link in all the way the proper loading (indicated by plate current)is reached when the load is about 100 ohms. Of course if the load is 10 ohms and the link pulled out for proper plate current I need to be very careful not to pour the coals on with the plate voltage or the link will over heat. I have been able to load to proper plate current with a 300 ohm load but I had to parallel tune my link instead of series tune. As for SWR bridges, I think many people get the properties of loads and sources mixed up. All the SWR meters I have measure the match between the line and the load and they don't give a hoot about the source as long as there is no reactance in the line from the source. SWR is defined as the ratio of transmission line to load. Not source to line. Given the scenario of a XMITER (say 100 watts) that has been adjusted to match a 50 ohm dummy load on a 1/2 wave length of coax cable and the SWR meter is at the load end of the cable. If the load resistance is increase to 100 ohms the SWR meter should show 2:1 and the transmitter should have 1/2 output RF current, Hence 1/2 power. If the transmitters load is adjusted to compensate and bring the RF current and plate current back up to normal it will be putting out 100 watts again. But the SWR meter should still show 2:1. The 100 ohm load will get all must a hot as the 50 ohm load and in many cases you will not be able to tell the difference in temperature. If there is a slight difference it will be caused by the slight increase in loss of the transmission line due to the SWR of 2:1. This is generally not of any consequence on 80 or 40 meters. For the most part the load is still getting the 100 watts even though it is 100 ohms instead of 50 ohms. By the same token many SWR meters that are not at the load end of the cable may not give the correct reading and especially if the source is not a resistive output as most transmitters are not unless they or pre adjusted with the desired load attached with a very short cable. The reason I said a 1/2 wave length of coax in the above scenario, is because that with a 1/2 wave length (must take in effect of slow velocity of coax) the value of load resistance is reflected at the source. At a 1/4 wave length is either multiplied of divided by the SWR depending on whether the load is greater that the line characteristic impedance or less than it. Of course if the SWR is 1:1 then it doesn't matter how long the line is or where you measure it. The only need I have found for an SWR meter is, as an indicator of the tuning of an antenna tuner for random length wire or balanced line doublets. Also many solid state radios have no tuning built in and can only work right into a 50 ohm non reactive load. In this case a PI type tuner for coax fed antennas is very useful for fine tuning to the proper load. (Basically, it takes the place of an internal tune and load procedure, as older tube type radios had.) The SWR meter is a good indicator to use when it is placed at the input of the tuner and the transmitter has been pre-tuned into a 50 ohm dummy load. When the antenna tuner is adjusted correctly, as indicated by the SWR meter, the transmitter will be loaded just as it was with the dummy load and will not have to be retuned. SEE http://www.qsl.net/wa5bxo/swr/swr.htm John, WA5BXO
RE: [AMRadio] Ladder-line mounting question
Hi John, Ed is correct. Better to be safe. The effect of an impedance bump is a relative thing. Higher frequencies are affected more. The position of the bump on the line will affect its size. Having a piece of metal near a low Z point on the tuned line will have less effect, perhaps none, than when it is at a high Z point. High and low Z points are found .25 wavelengths apart. A high Z point can be found by watching the SWR meter that is in the coax line (between the tuner and the XMTR) while moving a screw driver or other piece of metal (that has insulation over it so as not to short the Xmision lines) up and down the line. This type of testing generally requires two people, one to move the interfering object and the other to watch the meter. When the screw driver is near a low Z point it will have very little effect on the SWR meter but when it is over a high Z point the SWR meter will change a lot more. If there is very little difference from one point to the other, then it may be that you have "inadvertently" matched the load to the line. That's a joke because I have yet to accomplish this feat with out special pruning. At any rate, it will not be the same on all frequencies. Back in the days of the full 1KW input, I had a doublet up and feed with open wire line. I had the line dropping down from the antenna above the house and looping under the edge of the roof where it then came to the balance tuner which was mounted just under the edge of the roof and against the outside wall. The balance line was insulated #12 wires and laid against the composition shingles just at the edge of the roof. When I first hooked it all up, it worked fine, but when I turned up the Variac to run the full KW input I found the in about 30 seconds the transmitter was out of resonance. The SWR meter was on the pin. I reduced the voltage and retuned the tuner outside and all was well again. About 30 seconds after I increased the power it started drifting out of tune. This time I inspected the antenna and Xmision line to find that the line had melted the roofing material where it past over the edge and was now 1 to 2 inches embedded into it and lying against the roof edge flashing. I placed a piece of Plexiglas under the shingles and notched the outside edge of the plastic to hold the line wires in place, spacing them about 4-5 inches away from the roof. The tuning then was stable. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Edward B Richards Sent: Sunday, October 23, 2005 12:06 PM To: amradio@mailman.qth.net Cc: amradio@mailman.qth.net; [EMAIL PROTECTED] Subject: Re: [AMRadio] Ladder-line mounting question Just to be safe why not suspend the ladder line with long plastic cable ties? This will keep it at least 6 inches from any metal. Good Luck. 73, Ed K6UUZ On Sun, 23 Oct 2005 12:30:20 -0400 (EDT) John Lawson <[EMAIL PROTECTED]> writes: > > >Just got my fence-perimeter NVIS loop installed yesterday (thanks > to > the kind slave-labor assistance of Brad, KB7FQR). I'm using 450-ohm > > feedline from the loop back to the tuner in the shack. It comes thru > a > hole in the shack wall and I had planned to suspend it along the > rafters > on those large 'bicycle hooks' for the 20 or so feet from the entry > point > over to where the Gear all lives. > > It has been suggested that this is a Not Good Thing - that any > metallic > object like that touching the ladder-line will alter the impedance, > stress > the insulation, etc. > >I can see the insulation concern, but I don't get how a pice of > 3/8ths > steel rod covered with plastic at right-angles to the feedline > conductors > can make much of an impedance bump. > >So I thought to solicit the general wisdom of those of us who > might know > the real 411 on this subject, because I'm not the brightest bulb in > the > marquee when it comes to HF antennae and feedlines. > > > > Cheers > > John KB6SCO > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > AMfone Website: http://www.amfone.net > AM List Admin: Brian Sherrod/w5ami > > __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
RE: [AMRadio] need help
Depending on how critical your rice box is about having a pure 50 ohm load on it and the amount of voltage required at the grids of the amplifier, you may want to use a small tuner between the two but nearest the amp. If a less critical amount of match is required a balun or .25 wavelength 75 ohm ooaxial cable match might be used. John, WA6BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Edward B Richards Sent: Tuesday, October 18, 2005 10:27 PM To: amradio@mailman.qth.net Subject: [AMRadio] need help Hi, you guys who are better educated than I. I want to drive a linear amplifier with a rice box that requires a 50 ohm load. The linear amp uses an input to a 170 ohm, 80 watt swamping resistor to ground, then through a .001 mfd capacitor, then through a VHF parasitic suppressor consisting of 4 turns of wire around a 47 ohm resistor, to the grids of a pair of parallel connected 4-400A tubes. What I need to know is the impedance of the input. Is it close to 50 ohms or do I need to use a matching network between the rice box and the linear amplifier. Thank you. Ed K6UUZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
RE: [AMRadio] The zeal to eliminate AM mode on the amateur bands.
Well Brian it seems that Western Electric is the culprit, in 1915s or 1920s. It would be impossible to speak directly with any of the founders as I'm sure they are gone but I wonder if there are folks that have a BIO on the individuals that worked on the project. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bob Macklin Sent: Sunday, September 18, 2005 8:54 PM To: Discussion of AM Radio Subject: Re: [AMRadio] The zeal to eliminate AM mode on the amateur bands. Brian comments: "H - I thought SSB was developed by the telephone companies or the military back in the 1930s, rather than by AM ham ops. Maybe I was given wrong information." SSB was devleoped by AT&T in the 20's for use on the Trans Atlantic cable. Bob Macklin K5MYJ Seattle, Wa. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
RE: [AMRadio] The zeal to eliminate AM mode on the amateur bands.
Brian,
You are probably correct on the organizations credited for SSB
engineering. My point was that AM was what was studied and had to exist
before SSB and it was the same type of mind set that did the
engineering. I would bet they were hams that made a living doing what
they enjoyed. What little I know of history but I have found that many
people with the design and engineering bug are hams, and that the ideas
they have, stem from their experiences in amateur radio. I would guess
that it happened something like this. An over simplification I am sure!
1. An old AM rig is being operated by an engineering and resourceful
individual.
2. He gets better receiving equipment where he can notch out an unwanted
carrier or narrow down the band pass for CW. (He probably built or
modified the receiver)
3. He finds that tuning off the side and notching the AM carrier causes
distortion. Reinserting the carrier with a LOCAL BFO improves reception.
4. Experiments and learns all the spectrum parameters of AM discovering
that the intelligence is in one sideband.
5. He works with others at work to come up with a phasing system to
eliminate the carrier (Work done by GE I think, help me here Don, K4KYV)
Later, comes up with audio phasing so that one side band can be
eliminated.
6. Collins comes up with better filtering circuits and decides that the
filtering circuit is better for the military systems due to its
simplicity for the user and get a contract with the military.
7. Mean while, back on the ranch, hams that work for "Bell Tell" are
trying to do multiplexing using independent DSB.
The scenarios could go on and on but I bet they were HAMS and had AM
rigs in 1930.
John, WA5BXO
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
[EMAIL PROTECTED]
Sent: Sunday, September 18, 2005 7:32 PM
To: Discussion of AM Radio
Subject: RE: [AMRadio] The zeal to eliminate AM mode on the amateur
bands.
H - I thought SSB was developed by the telephone
companies or the military back in the 1930s, rather than by
AM ham ops.
Maybe I was given wrong information.
On 18 Sep 2005 at 18:21, John Coleman ARS WA5BXO wrote:
> Yes, AMers are mavericks but I feel that the ones that did not
> go to SSB (100%) back in the 60s and 70s, are the ones that didn't
have
> any trouble communicating with whom ever they wanted and for the most
> part this took place because they were very knowledgeable folks with a
> desire to experiment and modify, or build from scratch, a better rig.
> ("That was a run on sentence if there was", somebody help me with
that.)
> Where as, the folks that just wanted to talk, collect cards and handle
> traffic found that buying a new SSB rig made that easier. I don't
think
> there is anyone among us that will deny the communication capabilities
> of a good SSB station. What many folks do forget is that the
engineers
> that researched and designed the SSB technologies were AM ops with
> mostly home brewed or highly modified stuff. Where do you think the
> ingenuity and knowledge to design the SSB stuff came from? I don't
mean
> to put down the folks that like to handle traffic, etc. There
expertise
> is certainly welcome in any part of the world. A lot of these
arguments
> can be said for CW as well. But when a SSB station, running 100
watts,
> can't cut the mustard or the rig don't work, I would be willing to
bet
> there or a lot of us AMers that could build a self oscillating single
> tube or Xsistor transmitter and be on the air with CW in short order
> with some junk parts.
>
> What I am saying is that it takes all sorts of people with
> expertise in different areas to make this hobby work and if we forget
> the old technologies then where are the building blocks for the
future.
> And if there is only a few modes to operate then where is the
incentive
> to learn.
>
> There will always be some nuts that go buy a rig just to get on
> the air and talk trash. They were there in the 50s, 60s, and 70s as
> well.
>
> I love to find a use for things for which it was not intended.
>
> John, WA5BXO
>
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Bob Bruhns
> Sent: Sunday, September 18, 2005 5:39 PM
> To: Discussion of AM Radio
> Subject: Re: [AMRadio] The zeal to eliminate AM mode on the amateur
> bands.
>
> It's because a lot of people in authority are
> control freaks. Control was the reason they went
> after authority in the first place, and they
> consider it to be the proper reward for their
> work.
>
> AMers have long been mavericks, often behaving a
> bit wildly and holding unusual opinions, and above
> all being highly visible and audible on the ban
RE: [AMRadio] The zeal to eliminate AM mode on the amateur bands.
Yes, it's true to some extent, for some it may be a hobby as you described but for a lot of us it is some thing that we look forward to spending a lot of time with and has become a very major part of our lives and our families lives, some times to the dismay of others in the family. I am very fortunate to have the support of my wife in these ham radio things. She used to like to travel with me to meet the other people but now days all we have time for is rearing kids and doing scout activities. That's not a bad thing, but we do look forward to the future of not being locked down so much. Of course with the fuel cost the way it is, we may not do a lot of traveling to meet others in the future. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Harmon Sent: Sunday, September 18, 2005 7:08 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] The zeal to eliminate AM mode on the amateur bands. As bad as any of the mentioned groups are on AM ...and in fact amateur radio in general is the increasing difficulty of putting up a HF antenna. ANY HF antenna. I am going through a lot of trouble to find a place to buy that will allow anything at all. Yes, I know that I may have to have a home built but I really don't want to mess around with contractors. You would think in all the millions of acres of nothing around here that hamming would be easy..wrong. One more thing.a hobby is something you do if you are totally bored and have absolutely nothing else to do. I think most hams and especially everyone on this list that this is not a hobby. I don't know what the hell it is but it is not a hobby. Regards Dave Harmon NSRCA 586 K6XYZ[at]valornet[dot]com Broken Arrow, Ok.
RE: [AMRadio] The zeal to eliminate AM mode on the amateur bands.
Yes, AMers are mavericks but I feel that the ones that did not
go to SSB (100%) back in the 60s and 70s, are the ones that didn't have
any trouble communicating with whom ever they wanted and for the most
part this took place because they were very knowledgeable folks with a
desire to experiment and modify, or build from scratch, a better rig.
("That was a run on sentence if there was", somebody help me with that.)
Where as, the folks that just wanted to talk, collect cards and handle
traffic found that buying a new SSB rig made that easier. I don't think
there is anyone among us that will deny the communication capabilities
of a good SSB station. What many folks do forget is that the engineers
that researched and designed the SSB technologies were AM ops with
mostly home brewed or highly modified stuff. Where do you think the
ingenuity and knowledge to design the SSB stuff came from? I don't mean
to put down the folks that like to handle traffic, etc. There expertise
is certainly welcome in any part of the world. A lot of these arguments
can be said for CW as well. But when a SSB station, running 100 watts,
can't cut the mustard or the rig don't work, I would be willing to bet
there or a lot of us AMers that could build a self oscillating single
tube or Xsistor transmitter and be on the air with CW in short order
with some junk parts.
What I am saying is that it takes all sorts of people with
expertise in different areas to make this hobby work and if we forget
the old technologies then where are the building blocks for the future.
And if there is only a few modes to operate then where is the incentive
to learn.
There will always be some nuts that go buy a rig just to get on
the air and talk trash. They were there in the 50s, 60s, and 70s as
well.
I love to find a use for things for which it was not intended.
John, WA5BXO
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Bob Bruhns
Sent: Sunday, September 18, 2005 5:39 PM
To: Discussion of AM Radio
Subject: Re: [AMRadio] The zeal to eliminate AM mode on the amateur
bands.
It's because a lot of people in authority are
control freaks. Control was the reason they went
after authority in the first place, and they
consider it to be the proper reward for their
work.
AMers have long been mavericks, often behaving a
bit wildly and holding unusual opinions, and above
all being highly visible and audible on the bands.
Guys with sideband gear didn't like the whistles
and the sibilent splash, and control freaks went
nuts wanting to rein in the independent and
outspoken AMers.
SWLs would tune the bands, but sidebanders sounded
like Donald Duck, so the AMers were the ones the
SWLs listened to. The control freaks sure didn't
like that!
So it went for many years. The sideband guys are
still opposed to AM, and the control freaks still
want control. There is not enough real activity
on the bands to justify any conflict, but the
control freaks still want control, and their
failure to establish that control has made them
really angry. Hence the zeal to eliminate AM.
Bacon, WA3WDR
- Original Message -
From: "Mark Cobbeldick [KB4CVN]"
<[EMAIL PROTECTED]>
To:
Sent: Sunday, September 18, 2005 1:10 PM
Subject: [AMRadio] The zeal to eliminate AM mode
on the
amateur bands.
> Having only been active on AM mode for just two
short
years, I consider
> myself to still be a newbie, still not
understanding
the zeal and
> fervor by some in the amateur community to
eliminate
or totally outlaw
> the use of AM mode transmissions in the MF/HF
amateur
bands in the USA.
>
>
> ...As quoted by one person "like using
spark-gap".
>
> I look at AM communications as just one of the
earlier modes, something
> to be preserved, not cast aside.
>
> Could someone more familiar with the issue
please
give me a better
> understanding of why these people are so intent
to
get rid of this
> mode?
>
>
> 73,
> Mark Cobbeldick, KB4CVN
> Monroe, VA
>
>
__
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protection around
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>
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>
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AMRadio mailing list
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AM List Admin: Brian Sherrod/w5ami
RE: [AMRadio] Drying out HV transformers / Chokes
The "Idea" is for us rednecks, that have a car sitting around that we don't drive, is not drivable, or we can't afford to buy gas for it. Truth be known, that a totally sealed up small space such as a trunk of a car, may not work to well because the "air saturation with water" would probably occur before the XRMR was depleted of water. Perhaps you could open the trunk once in while on a day of low humidity and then close it back up for a while longer. Of course if you did drive it around and can afford the gas then perhaps a positive crank case ventilated vehicle could be modified so that the air intake for the crank case came from the trunk. HIHI I can see the next Jeeves cartoon now! John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Sunday, September 18, 2005 4:50 PM To: Mike Dorworth, K4XM; Discussion of AM Radio Subject: RE: [AMRadio] Drying out HV transformers / Chokes Hmmm, been most interesting. If I tried this with my 1999 Dodge Stratus, and my open frame BC-610 transformer, two things would occur: 1.) rust since my trunk seal leaks 2.) my gas mileage will suffer noticeably as well as car handling and maybe, 3.) If I get into an accident, the dang thing might smash me where I sit in the drivers seat. A BC-610 transformer flying through the air is not easily stopped! Regards, Jim WD5JKO
RE: [AMRadio] Drying out HV transformers / Chokes
I have a modulation XFMR that was under muddy water for 6 months. I thought it had some how floated away in the "Spring, Tx flood of 94", But I just didn't understand how it would be possible. That's another story, where was I, Oh yeh, the XFMR was found and the mud was off of it. It was let to stand in the sun for about 3 months under shed. I then measured 1000 ohms from any winding to another and to ground. I took the end caps off exposing the coil, rust and mud. Washed it out some more and decided to put it on the shelf in a un-air conditioned office that no one used, where the temp would reach 120-140 every day in the summer. I was thinking I would rewind it some day. But alas, 6 months later all the readings were infinite. To be safe it was mounted on a wooden shelf in the XMTR and has been working for the last 7-8 years. Modulator is four 813s with 2500 volts on the plates, 800 on the screens and about -100 on the grids. This modulator will pump out some PTP voltage. I was really surprised at the come back of this XFMR. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Don Lemley Sent: Saturday, September 17, 2005 11:51 PM To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; AMRadio@mailman.qth.net Subject: [AMRadio] Drying out HV transformers / Chokes Hi all, Ok, I know this has been covered here before, but is there a consensus on how to get the moisture out of HV plate transformers and chokes, so they won't arc on me. And before everyone jumps in with the quick "just put it in an oven on xxx degrees for yy hours", I am working with the iron from a Broadcast transmitter, specifically, the Gates BC-1G so these things are 100, 150 lbs each, and my XYL would REALLY not like it if I tried to put them in her fancy oven. They have been sitting in an un-conditioned but dry hanger/garage for several years, so I am certain they have soaked up a good deal of moisture over that time. Thanks for any suggestions, Don - W8HRQ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami
[AMRadio] Choke calculations
Hey Bob: I just realized that each Henry of inductance is equivalent to 376.8 ohms at 60 Hz. I don't know why, but at my age now, little revelations of that nature excite me. John, WA5BXO
RE: [AMRadio] BPL, ARRL on NPR Morning edition Tuesday
If it were me planning the broadband solution I would commission the Telco to do it or be taxed more because I think, as you do Jack, that the Telco's wires and fiber or more suited for the job. To me, BPL is like using a 6BK4 (a triode with extremely high gain) for a preamp but the plate supply is 20,000 volts. John, WA5BXO --Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, August 17, 2005 7:15 PM To: Discussion of AM Radio Subject: Fw: [AMRadio] BPL, ARRL on NPR Morning edition Tuesday Before someone tells me how stupid I am, please correct ride-of-ways to right-of-ways in my previous rant. What can I say, I was in a hurry. I still think BPL is a travesty and a cruel lie being foisted upon the public at our expense!! 73, Jack, W9GT - Original Message - From: <[EMAIL PROTECTED]> To: "Discussion of AM Radio" ; "Discussion of AM Radio" Cc: "Bob Bruhns" <[EMAIL PROTECTED]> Sent: Wednesday, August 17, 2005 3:25 PM Subject: Re: [AMRadio] BPL, ARRL on NPR Morning edition Tuesday > The "phone companies" are not just wire line companies any more!! They are > not just interested in wire and wireless services, but getting fiber > optics to your house. With fiber, you can have nearly unlimited bandwidth > that can provide telephone, data (high speed internet service), video > (replace CATV), and perhaps many other new services that they haven't even > thought of yet. The power companies want a piece of the pie, but they are > just kidding themselves if they think they can compete wth a garbage > service like BPL. It is , by far, a technically inferior service. It > also , unlike any other "landline based services", has the potential to > create damaging interference to existing licensed RF-based services on the > HF spectrum. > > If the power companies were smart (??) they would use their ride-of-ways > to build fiber optic backbones. They could also partner with telecom > companies to provide services at competitive prices instead of causing > disruption and discourse!!! > > Just my 2 cents worth as a 35 year veteran of the telecom business. > > 73, > Jack, W9GT > > -- Original message -- > >> I know the phone companies don't want to have to go >> into homes any more. They want some kind of RF link >> into the home so they just turn service on or off, and >> give people stuff to set up inside by themselves. I >> guess the cable companies would feel the same way. >> >> - Original Message - >> From: "John E. Coleman (ARS WA5BXO)" >> >> To: "'Discussion of AM Radio'" >> >> Sent: Wednesday, August 17, 2005 10:35 AM >> Subject: RE: [AMRadio] BPL, ARRL on NPR Morning edition >> Tuesday >> >> >> What I don't quite understand, is why it is easier or >> cheaper to do >> broadband over power lines than over phone lines. >> Phone lines are already >> balanced lines with a tighter EM field. Why wouldn't >> that be better? >> >> John, WA5BXO >> >> >> >> >> -Original Message- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of >> Merz Donald S >> Sent: Wednesday, August 17, 2005 8:56 AM >> To: 'Amradio (E-mail); 'Glowbugs (E-mail) >> Subject: [AMRadio] BPL, ARRL on NPR Morning edition >> Tuesday >> >> FYI. >> >> http://www.npr.org/templates/story/story.php?storyId=4801446 >> >> 73, Don Merz, N3RHT >> >> The information contained in this e-mail may be >> confidential and is intended >> solely for the use of the named addressee. >> Access, copying or re-use of the e-mail or any >> information contained therein >> by any other person is not authorized. >> If you are not the intended recipient please notify us >> immediately by >> returning the e-mail to the originator.(16b) >> ___ >> ___ >> AMRadio mailing list >> Home: http://mailman.qth.net/mailman/listinfo/amradio >> Help: http://mailman.qth.net/mmfaq.html >> Post: mailto:AMRadio@mailman.qth.net >> >> >> >> ___ >> ___ >> AMRadio mailing list >> Home: http://mailman.qth.net/mailman/listinfo/amradio >> Help: http://mailman.qth.net/mmfaq.html >> Post: mailto:AMRadio@mailman.qth.net >> >> __ >> AMRadio mailing list >> Home: http://mailman.qth.net/mailman/listinfo/amradio >> Help: http://mailman.qth.net/mmfaq.html >> Post: mailto:AMRadio@mailman.qth.net > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] info wanted on 4-400 linear amplifier
Sorry about the spelling! You may want to join in the mail group called AMPS CONTESTING lots of really smart guys their on linear amps. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Coleman ARS WA5BXO Sent: Wednesday, August 03, 2005 9:09 AM To: 'Discussion of AM Radio' Subject: RE: [AMRadio] info wanted on 4-400 linear amplifier Grid driven linear amps are a challenge sometimes even tetrode tubes need to be neutralized. Neutralization not only prevents spurious oscillations but it also stops phase modulation products. Swamping the grid circuit with a dummy load is a good idea because it reduces the 90 degree feedback that we are trying to neutralize and makes the driver radio a lot happier with a more constant load. The nice thing about grid driven is it would be easy later on to plate modulate and run it class C. As for linear amps I thing GG is a better solution especially with triode tubes made for the purpose. You may want to join in the mail group called AMPS CONSTESTING lots of really smart guys their on linear amps. John WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, August 02, 2005 8:10 PM To: amradio@mailman.qth.net Subject: [AMRadio] info wanted on 4-400 linear amplifier I am planning to build a linear amp around a grid driven 4-400 tube. Can anyone suggest where I can find a suitable circuit with component values. I would like band-switching for 80, 40 and 20 meters. I will be driving it with a 25 watt carrier output rice box on AM. I don't like the one in the ARRL 1967 handbook because it requires you to open the lid and physically change taps on the coil and change tuning capacitors. I don't have any other older handbooks. Thank you. Ed K6UUZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] info wanted on 4-400 linear amplifier
Grid driven linear amps are a challenge sometimes even tetrode tubes need to be neutralized. Neutralization not only prevents spurious oscillations but it also stops phase modulation products. Swamping the grid circuit with a dummy load is a good idea because it reduces the 90 degree feedback that we are trying to neutralize and makes the driver radio a lot happier with a more constant load. The nice thing about grid driven is it would be easy later on to plate modulate and run it class C. As for linear amps I thing GG is a better solution especially with triode tubes made for the purpose. You may want to join in the mail group called AMPS CONSTESTING lots of really smart guys their on linear amps. John WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, August 02, 2005 8:10 PM To: amradio@mailman.qth.net Subject: [AMRadio] info wanted on 4-400 linear amplifier I am planning to build a linear amp around a grid driven 4-400 tube. Can anyone suggest where I can find a suitable circuit with component values. I would like band-switching for 80, 40 and 20 meters. I will be driving it with a 25 watt carrier output rice box on AM. I don't like the one in the ARRL 1967 handbook because it requires you to open the lid and physically change taps on the coil and change tuning capacitors. I don't have any other older handbooks. Thank you. Ed K6UUZ __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Spelling and word substitution
For those of you that don't know, I am the worlds worst at using the wrong word and spelling. I don't mind getting corrected. Besides some of you can't get any jabs in any other time because I am seldom on the air much. HIHI Consider WIRLED PEAS John WA5BXO
[AMRadio] (no subject)
I have been asked a lot about the rig so I will send this out to the Group. http://www.qsl.net/wa5bxo/pkd-bxo/rebuild.html http://wa5bxo.shacknet.nu/HAMPICTURES/Pictures/Ham%20Radio/BIG_Rig.JPG http://wa5bxo.shacknet.nu/HAMPICTURES/Pictures/Ham%20Radio/Mic.jpg Movies and audio below provided below by W5OMR http://wa5bxo.shacknet.nu/HAMPICTURES/wa5bxo-on-the-air.wmv http://wa5bxo.shacknet.nu/HAMPICTURES/this%20is%20how%20we%20tune.wmv Your Welcome Herb The main AM rig is spread out into two rooms. It is mostly home brew and a lot of modifications. Even the scope is homebrew. The XMTR room that holds the 6FT rack cabinet is adjacent to the operations console. The 6Ft rack now holds the final amplifier which is a home brewed class C push pull pair of 250ths with link coupling input and output. Just below the Final chassis is the high level modulator chassis which is four 813s in push pull parallel class AB1. The power supplies for these are built in the back side and bottom of the rack cabinet. The modulator supply is 2500 Volts with its own plate XFMR and filters. The final supply is a separate supply with its own plate XFMR and filters but the primary of the plate XFMR for it is passing through a Variac, so that I can adjust the plate supply voltage on the final amp. I generally run about 1600 volts and some where between 300 to 400 milliamps of plate current. In the operations console of the other room is the HQ-145 RCVR and various other pieces of equipment. Most of the Equipment can be patched around in such a way that any of it can be used for carrier excitation to the AM big rig in the other room. Each piece can be operated in stand alone also. When on AM at 3885mhz, this is this is the general setup. The carrier generation begins with a modified TS820 putting out a carrier at about 10-20 watts. This goes into a Heath kit modified SB200 amplifier that brings this up to a 75 watt carrier. This then drives the big rig (PP 250ths) which puts out about 350 watts of carrier. The audio chain begins with a home brewed microphone built into and old Shure dynamic microphone housing. You may notice the 4 red LEDs inside the microphone. The output of the microphone feeds a Shure mixer with auto output leveling. The mixer feeds the main speech amplifier which is a much modified Bogen PA amplifier. The Bogen PA amp feeds the grids of the big modulator in the other room. The big modulator with the four 813s is capable of 1200 watts of audio but now days we only need about 200 watt from it so it sort of loafs along. The out put of the big modulator is feed to a 40 HENRY choke which K4KYV and I sort of built from 2 chokes, in series with the plate supply to final Class C carrier amplifier so that the audio can be imposed on the 1600 volt DC that is feeding the plate circuit of the 250th's. There is enough audio reserve to over modulate by 300 percent so you see the need for the Shure auto output leveling mixer. The out put of the big rig is feed into a home brewed balanced tuner that is mounted on the wall above the operations console. The 600 ohm balanced feed line from the antenna comes through a small Plexiglas window in the wall behind the tuner. The antenna and balanced feed line is made from number 12 wire. There is about 120 feet of the balanced feed line going up to the center of the dipole antenna which is just less than 100 ft high. There is about 125 ft of wire making up each leg of the antenna for a total antenna length of 250 ft. The ends of the ant are about 70 ft high. This type of setup is not your every day rig but is an accumulation of stuff over many years and my good friend BJ and I make it continue to evolve. Good Luck John WA5BXO -Original Message- From: Herb Raemsch [mailto:[EMAIL PROTECTED] Sent: Sunday, July 31, 2005 2:34 PM To: [EMAIL PROTECTED] Subject: Speaker Suggestions Hello John Thank You very much for the suggestions on the speaker. Appreciate it very much. Boy that is anice looking transmitter pictured on QRZ web-site. Was wandering what make and model. Anyways I appreciate your input very much. I have been on SSB to long and have forgotten a lot. At 64 am going back to CW and AM so its guys like you I lean toward for a little help. Thank You Herb WA3HGT
RE: [AMRadio](still selling stuff!
Well to be honest I never saw the inside of one but a friend of mine had one, at least I think that is what he had. Now I'm not sure. Was there another model XCVR by Gonset that was similar but had low level modulation? I did have a silver faced G-7--- something, mobile XMTR with separate power supply / modulator where the modulators were triode connected zero biased as you described. Was it a G-77? I just can't remember but it was not a XCVR, just a XMTR. I think it had a 6146 in the final and the modulators were 6DQ6s. The receiver I used was PMR7 Multi ELMAC. God, those were the good old days! John WA5BXO ---Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Friday, July 15, 2005 9:26 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio](still selling stuff! It uses two 6dq6 tubes as modulators, modulating a 6dq5. What you might remember is the modulator tubes use the screen grid or protection grid, not the regular control grid for audio drive, and are set up as zero bias triodes A very neat little rig. Brett -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John E. Coleman (ARS WA5BXO) Sent: Friday, July 15, 2005 9:53 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio](still selling stuff! I did not remember the G-76 as being a plate modulated rig but as a screen modulated instead. But then I am old and I forget a lot. John WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Friday, July 15, 2005 8:59 PM To: 'Discussion of AM Radio' Subject: RE: [AMRadio](still selling stuff! I am still cleaning out stuff I don't seem to use that has filled up the basement. Gonset G76 with home built power supply (looks very nice). This is a trans/receiver, sort of a receiver and transmitter in one small and really cool looking cabinet. 80 through 6 meters, VFO, plate modulated, puts out about 70 watts of carrier. __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Mike
Jim, That is an interesting circuit with the plate grounded and output taken from the screen grid as an anode. I don't quite see the advantage other than fewer parts. The gain seems to be about 10 db less if I read it right. Perhaps the screen to grid capacitance is much lower than an equivalent triode. As I see it a triode especially one with a lot of plate to grid capacitance is going to represent a large amount of "miller effect capacitance" to the crystal cartridge, similar to what you and I experimented with by placing the 1000pf caps from plate to grid of the 12AX7 input. This must have been equivalent to placing a .01 from grid to ground except it did provide some gain and special control. I would guess that a 10 meg grid leak resistor and 1 to 2 pf of plate to grid capacitance and a 12AX7 with a gain of about 40 would be about 100 pf to ground. I not sure how the math works on all that, but I do know that the higher the input resistance, or the high the gain is, the more "miller effect" is present. This could be a desirable thing for limiting high freq response while boosting the low freq response do to a greater RC time constant from the crystal representation the Bob described in another message. On the other hand a pentode connection with less plate to grid capacitance and miller effect would not attenuate the high frequency components and the full amplification of those signals would be realized with less phase distortion, not that anyone cares much about phase distortion at 10 - 15KCs. John Coleman WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim candela Sent: Tuesday, March 15, 2005 9:33 AM To: Discussion of AM Radio Subject: RE: [AMRadio] Mike Steve, I just was reading about this in my "Radiotron Designers Handbook" where a simple preamp using a 6SJ7 was used with a crystal microphone. In short you can use a higher grid resistance to change the frequency response (more lows), but the text describes the limitations involving reverse grid current, dc operating point shift, signal to noise ratio, dynamic range, and so on. There also is some alternative circuitry shown to give you some ideas if you want to do some extensive modifications. I find it interesting that they show the 6SJ7 in triode mode using two different techniques. I scanned in several pages, and have posted them on the net at the following link. The text is sideways, and you can turn image 90 degrees CCW with your Acrobat reader. Hope this helps. http://pages.prodigy.net/jcandela/Preamps/Mic_Preamps.pdf Regards, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Tuesday, March 15, 2005 8:25 AM To: amradio@mailman.qth.net Subject: [AMRadio] Mike Thanks Guys: This mike is for a vintage 1948 AM rack rig homebrew by W2PLY who moved into Senior Residence. The speech amplifier/modulator schematic is right from August 1947 QST. I got the rack and the 5 sections directly from the flat bed trailer at the estate sale...and now just about finished doing what very little fixin required. The article cites a crystal mike; it feeds directly into the grid of a 6SJ7 with no grid leak resistor. As I understand these things, the mike - what type of cartridge - needs to put out 'so many' microvolts necessary for the tube into which it feeds. And the impedance needs to 'match'. I understand there plenty of gain after the 6SJ7...and one of the 6SN7's has a "tone control" potentiometer in the grid. Personally, my voice is a little higher from center in pitch..and I'd prefer more lower than higher freq. response...which is generally a problem due to low freq. rolloff in the mike curves...that's why I'm eager to try this 'tone control'. I guess the first question is: what impedance number is required for a 6SJ7 grid? Your generous help is always appreciated. Regards, Steve WA2TAK __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.7.2 - Release Date: 3/11/2005 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.7.2 - Release Date: 3/11/2005 __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Series Modulator
Dennis, I don't have the 1954 Handbook to look at the article but, by definition, the series modulator is hooked up so that the entire power supply voltage going to the final is varied in accordance with the bias or audio on the modulator. It is High Level Plate Modulation, and the modulator tube must deliver 50 percent (average audio power for 100% modulation) of the DC input to the final class C device, just as with a XFMR coupled Plate modulator. The modulating device (tube or transistor) may be placed in series with the B+ lead (just as a secondary of a modulation XFMR) to the Final as a cathode follower with less than unity gain. This requires the audio going to the input to be higher than the modulation voltage. The modulating device may also be driven by a transformer with the output winding connected between grid and cathode of the modulator. In this way the modulator device has gain even though the output is still on the cathode which is connected to the plate circuit of the final. In the circuit that Jim (WD5JKO) has shown, the modulating device is connected in the cathode return circuit of the final. At first glance it might appear that the circuit is a cathode or bias modulator (similar to grid bias modulation). With closer inspection however, and you will see that the grid leak resistor of the class C final, is not returned to ground, but is instead returned to the cathode of the final. This little thing makes this a high level plate modulation system because the bias on the final (measured from cathode the grid) doesn't change anymore than it would with standard plate modulation. If the class C final voltage, measured from cathode to plate is 250 Volts then the modulator must be able to vary that voltage from 0 to 500 volts for 100% modulation. Typical this circuit will not be able to achieve 100% modulation but with careful adjustments it can get close. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, March 06, 2005 5:32 PM To: [EMAIL PROTECTED]; amradio@mailman.qth.net Subject: Re: [AMRadio] anyone for qrp am? In a message dated 3/6/05 3:02:36 PM, [EMAIL PROTECTED] writes: > Another alternative is series modulation. This has efficiency issues using > a class A series modulator, but for low power AM this might be the ticket. > Regards, > Jim > WD5JKO Essentially a form of grid modulation, see ARRL Handbook 1954 page 250 for a version using a 6SL7 and a 6Y6. I've heard these on the air sounding very good. Dennis D. W7QHO Glendale, CA __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Physical Reality of Sidebands
Hi again Larry. Yes, all this brings back old memories. I quit the TV repair business back in 1986 (I Think). Anyway started doing PC work and now I wish I could sometimes just run away and play with my toes in sand. HIHI CUL, 73 John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, January 19, 2005 7:48 AM To: Discussion of AM Radio Subject: RE: [AMRadio] Physical Reality of Sidebands Hi John, Yep I agree on all this. Actually I and Q as I remember was a Hazelteen (sp) patent that RCA had to buy. the R-Y B-Y detector was developed by RCA later to avoid the license fees from Hazelteen. Growing up into color TV near RCA's plants and Sarnoff was ben a bif help to me on early undestanding (college years0 of how color worked. I actually worked with RCA Sarnoff while DE at NJ Network on their first HDTV analog system which used yet another subcarrier in the imaginary plane at about 3 mhz to add the side panels for the wide screen. Amazing math tricks are used in all this. Kepp up the good work. Larry
RE: [AMRadio] Physical Reality of Sidebands
Yep, I know Larry, but I had already gotten deeper than I intended to. Because most of the video is motionless, the sidebands come out at multiples of the sweep rate. The color sub carrier frequency which is only transmitted in burst mode as previously describe, was chosen at the odd frequency that it is, so that in spectrum, most of the sideband energy containing the color info, would fall between the energy of the black and white info. This was in hope of having less "intermodulation" at the detector. As for I know, it was not until Magnavox produced the first COMB FILTER that we were able to make use of this bit of spectrum conservation. It is interesting to note that the color sidebands were 500KHz of upper and lower sideband spectrum except at the phase difference of around 80-100 deg where the flesh tones are produced and at that phase difference the band width is much greater but only on one sideband. The RCA CTC 4 chassis made use of this with the "I and Q" demodulation system, a very difficult sweep / band pass alignment procedure. This is all getting off the subject, but it was interesting to me that all this could be kept separate with the fast switching on and off of the burst and changing bandwidth of the I and Q modulated signal. I love all this type of discussion. I am afraid I would have to lean towards the theory, that it is what ever fits the need of the detector. At what wavelength does Electro-magnetic radiation become a particle? Is the Universe homogeneous or chaotic? That depends upon how it is observed. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, January 17, 2005 2:40 PM To: Discussion of AM Radio Subject: RE: [AMRadio] Physical Reality of Sidebands John, You are close. That was the old black and white days. Since color its divided down from 3.579454 to 15, 726.xx (approx) and vertical is 59,94 not 60.00. Larry W3LW On Sun, 16 Jan 2005 22:58:04 -0600, "John Coleman ARS WA5BXO" <[EMAIL PROTECTED]> wrote : > > Don, I have often pondered the same thing here is another example. > > The Horizontal sweep rate of a TV is 15750 hz. Every 1/15000 of > a sec there is a sync pedestal, and on the back porch of it is a burst > of a few cycles (as I remember it was 8 to 10 cycles in length) of the > color sub carrier (3.579545 MHz). This burst is removed and processed > by an amplifier that is key on by the horizontal retrace pulse which has > been synced to the horizontal sync pulse that rides atop the sync > pedestal just in front of the color burst. The 8 cycle color burst is > phase compared to a crystal oscillator in a phase locked loop. A good > synchronized scope can look at the full video detected signal and spread > the back porch of the sync pedestal out and view the 8-10 cycles of the > burst. I often wondered what a spectrum analyzer would look like when > monitoring the output of the burst amplifier with the phase detector > diodes remove. > > The burst amplifier was a simple tetrode whose plate circuit had > a parallel tank tuned to 3.58 MHZ and where the detected video was > applied to the grid through a small coupling capacitor that would > differentiate and pass the frequencies higher than 3 MHz. The grid leak > was returned to a circuit where a positive pulse from the fly back was > present to trigger the tube on. The output tank was link coupled to the > phase detector. > > > John, > WA5BXO > > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > > > __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Physical Reality of Sidebands
Don, I have often pondered the same thing here is another example. The Horizontal sweep rate of a TV is 15750 hz. Every 1/15000 of a sec there is a sync pedestal, and on the back porch of it is a burst of a few cycles (as I remember it was 8 to 10 cycles in length) of the color sub carrier (3.579545 MHz). This burst is removed and processed by an amplifier that is key on by the horizontal retrace pulse which has been synced to the horizontal sync pulse that rides atop the sync pedestal just in front of the color burst. The 8 cycle color burst is phase compared to a crystal oscillator in a phase locked loop. A good synchronized scope can look at the full video detected signal and spread the back porch of the sync pedestal out and view the 8-10 cycles of the burst. I often wondered what a spectrum analyzer would look like when monitoring the output of the burst amplifier with the phase detector diodes remove. The burst amplifier was a simple tetrode whose plate circuit had a parallel tank tuned to 3.58 MHZ and where the detected video was applied to the grid through a small coupling capacitor that would differentiate and pass the frequencies higher than 3 MHz. The grid leak was returned to a circuit where a positive pulse from the fly back was present to trigger the tube on. The output tank was link coupled to the phase detector. John, WA5BXO
RE: [AMRadio] QSL.Net
It's probably down for maintenance. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Geoff Sent: Thursday, January 06, 2005 7:12 PM To: Discussion of AM Radio Subject: [AMRadio] QSL.Net Is QSL.Net gone? All I get is "The Connection was refused when attempting to contact www.qsl.net." Looking up www.qsl.net www.qsl.net Making HTTP connection to www.qsl.net Alert!: Unable to connect to remote host. PING www.qsl.net (63.238.179.50) 56(84) bytes of data. 64 bytes from ftp.qsl.net (63.238.179.50): icmp_seq=1 ttl=239 time=77.9 ms 64 bytes from ftp.qsl.net (63.238.179.50): icmp_seq=2 ttl=239 time=84.8 ms 64 bytes from ftp.qsl.net (63.238.179.50): icmp_seq=3 ttl=239 time=330 ms 64 bytes from ftp.qsl.net (63.238.179.50): icmp_seq=4 ttl=239 time=77.2 ms --- www.qsl.net ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3003ms rtt min/avg/max/mdev = 77.260/142.759/330.918/108.674 ms Registration and WHOIS Service Provided By: directNIC.com Intercosmos Media Group, Inc. provides the data in the directNIC.com Registrar WHOIS database for informational purposes only. The information may only be used to assist in obtaining information about a domain name's registration record. directNIC makes this information available "as is," and does not guarantee its accuracy. Registrant: QSL.NET, Inc. 34087 Old Hickory Road Laurel, DE 19956 US 302-875-7979 Domain Name: QSL.NET Administrative Contact: Waller, Alan [EMAIL PROTECTED] 34087 Old Hickory Road Laurel, DE 19956 US 302-875-7979 Technical Contact: Waller, Alan [EMAIL PROTECTED] 34087 Old Hickory Road Laurel, DE 19956 US 302-875-7979 Record last updated 09-18-2003 06:59:29 PM Record expires on 01-29-2008 Record created on 01-28-1997 Domain servers in listed order: NS1.QSL.NET 63.238.179.1 NS2.QSL.NET 64.238.2.2 NS3.QTH.NET 63.238.179.3 NS4.SWL.NET 63.238.179.188 By submitting a WHOIS query, you agree you will use this data only for lawful purposes. You also agree that, under no circumstances, will you use this data to: a) allow, enable, or otherwise support the transmission by email, telephone, or facsimile of mass, unsolicited, commercial advertising or solicitations to entities other than the data recipient's own existing customers; or to (b) enable high volume, automated, electronic processes that send queries or data to the systems of any Registry Operator or ICANN-Accredited registrar. So, is it me, or is QSL.Net gone? 73 = Best Regards, -Geoff/W5OMR __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Matching a 100 watt PA am to drive 833'S
Perhaps I missed it but why would you want to change the 845 driver circuit, are you missing the tubes? John, WA5BXO
RE: [AMRadio] Metering circuits
Very good point Don John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donald Chester Sent: Sunday, January 02, 2005 6:04 PM To: amradio@mailman.qth.net Subject: [AMRadio] Metering circuits One word of caution. If you use the above circuit with directly heated cathode tubes, be very careful to avoid shorting either side of the filament line to ground. I lost a plate meter when I accidentally clip-leaded one side of the filament (I had intended it to be the xfmr ct) to ground, while running some tests. Half the filament voltage, in my case 5.75 volts, appeared directly across the DC millammeter terminals. It didn't actually burn out the coil in the meter before I realised the mistake and disconnected it, but by then it had literally shaken apart the movement. Don K4KYV __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] You Won't Believe This
What your speaking of Don is shown in the following article. http://www.qsl.net/wa5bxo/pptriodes/pptriodes.htm This article was started some time ago, for what reason I don't remember. I never had the chance to spend a lot of time with it so it probably has a lot of mistakes. If anyone wishes to help with the editing or add on something else please do so, mail it to me, and I will of course put your name on it. Another one, on SWR, I found that I forgot about is at http://www.qsl.net/wa5bxo/swr/swr.htm I think "BACON" had some input on this one but I'm sorry Bacon I can't remember for sure. It's another one that probably needs some help. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Donald Chester Sent: Sunday, January 02, 2005 5:11 PM To: amradio@mailman.qth.net Subject: Re: [AMRadio] You Won't Believe This >If you measure current from the filament transformer center tap to ground, >you'll have not only cathode current, but plate current, as well. Just >look >over at the grid current meter, subtract that from the plate meter, and >there's >your plate current, AND it's in a nearly ground potential position in the >series circuit. Return the grid leak resistor and/or PA bias supply to filament xfmr ct. instead of to ground, and your meter will read true plate current. If it is a screen grid tube, return the negative lead of the screen supply to filament ct. as well. Don k4kyv __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] You Won't Believe This
I gather from the text about the HV meter and current meter that the current meter is above ground by 4000 Volts. I know that there are a lot of special mounting devices and hardware for this purpose but I still feel that it is a bad idea. I have always made sure that HV current metering was done in the current path that is close to ground potential. As a further precaution it is a good idea to put a 50 Volt or less avalanche diode across the meter in case it should become open. As for the defection phenomenon, it might even be possible that the continued HV on the meter has put permanent static charge in the molecular structure of the plastic. If this is the case then any connection even a ground on the meter would cause a deflection. In any case I would move the current metering circuit to the cathode circuit or the negative return of the power supply. Modification of initial circuitry sometimes requires lifting all the ground connections of filters and/or chokes to get a floating ground and then passing that through the meter for current readings. I my opinion it is well worth the effort. I always put chokes in the negative lead of power supplies as well. It is an interesting phenomenon though. So please let us know what you do find as the cause. 73, John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of David Knepper Sent: Saturday, January 01, 2005 5:31 PM To: Discussion of AM Radio; Collins Mail List Subject: [AMRadio] You Won't Believe This That is right, only one lead connected and the meter is reading negative current. I switched this lead to the negative post and the meter still deflects downward past zero.
RE: [AMRadio] Windom
Here is some more superfluous (also unnecessary) info: The reciprocal of "reactance" is "susceptance". In a series circuit the "reactances" are null, at resonance, leaving only low resistance (OHMS). In a parallel circuit the "susceptances" are null, at resonance, leaving low conductance (MHOS). I had to look up "SUSCEPTANCE". HIHI I could not resist. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mike Dorworth, K4XM Sent: Friday, December 31, 2004 11:01 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Windom Boy are we down to the nity grity now!. Since one reactance is positive and the other negative that is leading and lagging or Eli the Ice Man so to speak, when they are added and the real componets are equal but the sines are opposite they CANCEL.. Happy New Year.. 73, Mike, K4XM
RE: [AMRadio] AM Usage with Linear AMPS
It is only SSB, but I used it to talk to all my buds on 75 and 40 while on trips across the US. I expected more than 150 watts out hen I whistled in the mike. John, WA5BXO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brian Carling Sent: Tuesday, November 23, 2004 6:25 AM To: Discussion of AM Radio Subject: RE: [AMRadio] AM Usage with Linear AMPS I thought that the WRL DuaoBander mobile was only SSB. On 22 Nov 2004 at 22:11, John Coleman, ARS WA5BXO wrote: > My experience (which is very little when it come to these sweep tube > rigs) is they or rated for a belch or some thing short and don't hold up > to a fix channel field day adventure with out tube replacement. I had a > DuaoBander mobile for a while rated a 400 watts PEP input I never saw > more than 150 watts output while whistling in the mike. It was in > perfect condition and would light a 50 watt bulb with normal speech. I > thought it would have blown it out. I was very disappointed. Yet, it > was one of the most heard radios all over the country by many AMers in > the late 80s. > > > John, WA5BXO > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brian Carling > Sent: Monday, November 22, 2004 9:55 PM > To: Discussion of AM Radio > Subject: RE: [AMRadio] AM Usage with Linear AMPS > > Aren't there a lot of commercially built amateur radio linear > amplifiers and RF finals that exceeded he manufacturers MAX > Pdiss rathings over the years, by adding a COOLING FAN to take > away the extra heat? > > One thinks of MANY sweep tubes rated for so-called Pdiss of 16 > watts and 20 watts that are regularly run at hundreds of watts of > RF! The tubes don't seem to melt. > > I think of the ubiquitous 6JS6C with a rating of 30 watts. > Yaesu ran a pair of these at 260 watts input in their FT101 series. > Many guys ran them at 260 watts p.e.p. on SSB and 260 watts CW. > Assuming 65% efficiency, you have 35% of 260 watts going into > the plates. That is to say 91 watts split between the two tubes. > UH oh - POP! But no, they didn't. > > Then when you throttle that FT-101 back to 40 watts input on AM > and go to your 30% efficiency (if it is) then you are actually > putting only 20 watts carrier per tube which is SAFER. > > Is that correct? > > How about some of the othre rigs that rated their 2 sweep tube > finals for 560 Watts or even 800 watts!? > > Then youhave peak Pdisses of 140 to 200 watts between the two > sweep tubes, most of which are rated for no more than 40 watts. > > > > > > __ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] AM Usage with Linear AMPS
Hi Brian: Consider what the efficiency is with no drive. The tube is drawing current and has voltage therefore it has input power but no output. Efficiency is 0%. As input drive is applied the efficiency increases but so does the plate current. The trick is to reach the 25% power point (or 50 Voltage point if monitoring on a scope) with out hitting the spot where the dissipation is 65 watts / 811A. John, WA5BXO
