RE: [AMRadio] AM transmitter coming available
WHAT IS THE WEIGHT AND SIZE?WILL IT FIT OK IN A PICKUP BED? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, March 17, 2006 7:50 PM To: Discussion of AM Radio Subject: RE: [AMRadio] AM transmitter coming available WOW http://www.nrcdxas.org/articles/bta5t/ Original Message Subject: [AMRadio] AM transmitter coming available From: Robert A. Poff [EMAIL PROTECTED] Date: Fri, March 17, 2006 9:16 am To: AM Radio List Server amradio@mailman.qth.net I'm in the process of getting approval to dispose of our good old RCA BTA-5T transmitter. Sad duty, since it's the rig I grew up listening toand I don't have the room to take it.. This is a 5 KW/1KW AM transmitter in operating condition, currently on 910 KC. Three phase power. This one has been modified with ceramic tubes in the modulator (3CX3000's if I remember correctly). Essentially a drop-in change. The company would like to get $500 for the rig. There is still a small chance they may want to part it out throughout the company. But if they decide to dispose of it, you pick up in York, PA. Anyone interested? Robert A. Poff / WB3AWJ Chief Engineer WSBA / WARM-FM/ WSOX Susquehanna Radio Corp. __ 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] RE: AM transmitter coming available
WHAT IS THE WEIGHT AND SIZE?WILL IT FIT OK IN A PICKUP BED? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, March 17, 2006 7:50 PM To: Discussion of AM Radio Subject: RE: [AMRadio] AM transmitter coming available WOW http://www.nrcdxas.org/articles/bta5t/ HAHAHA!now thats funny! If it were the 1KW version I'd say it possibly would fit in a good sized pickup being the size of a good hefty refriderator. But a small trailor would be needed to haul the iron. This 5KW box needs more than a pickup truck [currently maintain an RCA BTA 1R1] Bob Carter - KC4QLP - Mid-Atlantic-Engineering-Services of Utica NY / Elizabeth City NC http://www.geocities.com/midatlanticengineeringservice WKVU-FM Utica/Rome NY, WKVJ-FM Dannemora/Plattsburg NY, WRCS-AM Ahoskie NC - Echolink/Repeater 145.240/- PL 131.8 node 56703 Echolink/Link [future 10 meter node] node 56704 Echolink conference server node 267137 [*KC4QLP*] Echolink conference server node 290251 [*KC4QLP-C*]
Re: [AMRadio] AM Linear Operation
Hi Mike, I'm sure it's been all hashed --- and re-hashed! --- here before, but a good rule of them is this: to determine the (safe!) carrier output capability of your linear amplifier in the AM mode, take note of the plate dissipation of your tube(s) from the tube manual, then divide by two... Example --- I have a pair of 813's in parallel here: a single 813 can dissipate 125-watts, so that's 62+ watts of dissipation, times two, equals 125-watts in total. Adjust your drive accordingly so as not to exceed this value, all the while monitoring RF output on a watt meter. When speaking, it's always advisable to monitor your signal on a scope, too...I use a Heathkit SB-610 monitorscope here, in the trapezoidal position... Works for me! ~73~ Eddy VE3CUI - VE3XZ - Original Message - From: Mike Duke, K5XU [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Friday, March 17, 2006 11:21 PM Subject: [AMRadio] AM Linear Operation I've been reading this AM linear thread with great interest. I currently run a TS570 which gives me no more than 25 watts of carrier, plus a bit more on modulation peaks. I have an unmodified DX60 that I intend to put back in service later this summer after a shack painting project is finished. (No need to move it twice!) Because I enjoy operating, and would like to do so with enough signal to be heard reasonably well on 80 and 40 meters, I too have been considering which linear to run on AM. This discussion of linears on AM has caused me to reason that there is no exact magic combination of carrier drive level and audio level which is guaranteed to produce a cleanly amplified AM signal. For me, at least, this apparent fact is most unfortunate indeed. My signature will give you a hint of the usefulness of a scope in my shack. So, do I sit on my hands and wait for better propogation on the higher bands, or do I continue serving as the pin-drop test for all those restored 75A4's, HQ170's etc? Mike Duke, K5XU American Council of Blind Radio Amateurs __ 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] BC-610 Modulator feedback - and notes
Rick, Additionally, there should be NO shield on the 2A3s. The entire transmitter was designed to function with CONVECTION or OPEN air cooling. There is only ONE tube that has a shield. It is the oscillator deck 6L6. It SHOULD be a metal jacketed tube. The 1/4 X 20 bolts on top of BC-610(X)s were intended for the mounting of the BC-939(X) antenna tuners. Since the BC-614(X) speech amp is fully enclosed w/o vents, I, for one, would be very hesitant to use it on top of the BC-610(X). All the heat from below would add to the heat inside the speech amp. The components probably weren't designed for THAT additional heat. The BC-614(X) has a long enough connecting cable to place it on the operating bench. Pay close attention to WB2FCN, Jim! He restored my first one. He has carnal knowledge of these BEASTS and has helped MANY get them up and going. Bob - N0DGN James M. Walker wrote: I'll bet you a nickel the bias supply has a problem, the plate supply for the 2A3s is not normal the plate supply is achieved by putting a negative voltage on the 2A3s cathode to raise hte plate to 360 volts. Sounds like the bias supply voltage is off. Check the manual and then the components that provide voltage to the 2A3s Jim WB2FCN YMMV - Original Message - From: Rick Brashear [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Friday, March 17, 2006 6:10 PM Subject: Re: [AMRadio] Modulator feedback Thanks Mike. I just made a discovery about the 2A3 A-F drivers. I had a set of matched NOS RCA tubes in there. The feedback seemed to be coming from the area of those tubes more so than anywhere else. So, I exchanged them for another pair I have and it seemed to help quiet the feedback. Obviously, microphonics in the 2A3's is a factor. Next I looked for shields for the tubes, but have none, so I used a poor man's shield, a couple of pieces of aluminum foil. It helped considerably! As a matter of fact, I could then advance the audio of the speech amp enough to achieve good modulation. So, I am now on a quest to find some way of shielding the 2A3's. I'm afraid my temporary foil shields would cause the tubes to over heat, plus it's not the best way of doing it. Have you had any experience with this? I wonder if the 100th's are also part of the problem. I really think the talk back is coming from the modulation transformer, which I can live with. I just have to get the feedback out of it. Thanks for your assistance and advice, Rick/K5IZ Mike Sawyer wrote: Rick, The UTC may work so don't discount it. Those I and H model transformers were only about half the size as the D and E models. I can't think of the company that made them but they were substantially different then the earlier models. As always, your mileage may vary. Mod-U-Lator, Mike(y) W3SLK __ 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 -- Bob - NØDGN Bob Bethman - NØDGN \\//\\// (@ @) (@ @) +---oOOo-(_)-oOOo--oOOo-(_)-oOOo---+ | NØDGN AMRadio Manassas, VA|REAL Tube Radio and AM| +---+--+ | Manassas Radio - Home of Homemade Kielbasa Pirogi| +---+--+ | Bob Bethman\\\|/// The absence of a danger | | rbethman(at)comcast.net \\ ~ ~ // signal does *NOT* mean | | (/ @ @ /) that everything is OK | +-oOOo-(_)-oOOo+ | http://home.comcast.net/~rbethman| | 1 BC-61ØI w/BC-614I,1 T-213/GRC-26 w/BC614I 1 '51 Collins R-390A | | SP-600/NR Type 159, Heath DX-60, Apache, Mohawk, SX-101, HT-32A | +---.oooO---Oooo.---.oooO---Oooo.--+ | () () () () | |\ ( ) / \ ( ) / | | \ _) ( _/ \ _) ( _/| +--+ | Amateur Astronomer - Celestron Nexstar 8 | | 12 f5 Dob coming soon! Being built | |
Re: [AMRadio] BC-610 Modulator feedback - and notes
Rick, Additionally, there should be NO shield on the 2A3s. The entire transmitter was designed to function with CONVECTION or OPEN air cooling. There is only ONE tube that has a shield. It is the oscillator deck 6L6. It SHOULD be a metal jacketed tube. The 1/4 X 20 bolts on top of BC-610(X)s were intended for the mounting of the BC-939(X) antenna tuners. Since the BC-614(X) speech amp is fully enclosed w/o vents, I, for one, would be very hesitant to use it on top of the BC-610(X). All the heat from below would add to the heat inside the speech amp. The components probably weren't designed for THAT additional heat. The BC-614(X) has a long enough connecting cable to place it on the operating bench. Pay close attention to WB2FCN, Jim! He restored my first one. He has carnal knowledge of these BEASTS and has helped MANY get them up and going. I've also resent this to INCLUDE the T-368 BC-610 group, WHICH, you may wish to join Rick. Bob - N0DGN James M. Walker wrote: I'll bet you a nickel the bias supply has a problem, the plate supply for the 2A3s is not normal the plate supply is achieved by putting a negative voltage on the 2A3s cathode to raise hte plate to 360 volts. Sounds like the bias supply voltage is off. Check the manual and then the components that provide voltage to the 2A3s Jim WB2FCN YMMV - Original Message - From: Rick Brashear [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Friday, March 17, 2006 6:10 PM Subject: Re: [AMRadio] Modulator feedback Thanks Mike. I just made a discovery about the 2A3 A-F drivers. I had a set of matched NOS RCA tubes in there. The feedback seemed to be coming from the area of those tubes more so than anywhere else. So, I exchanged them for another pair I have and it seemed to help quiet the feedback. Obviously, microphonics in the 2A3's is a factor. Next I looked for shields for the tubes, but have none, so I used a poor man's shield, a couple of pieces of aluminum foil. It helped considerably! As a matter of fact, I could then advance the audio of the speech amp enough to achieve good modulation. So, I am now on a quest to find some way of shielding the 2A3's. I'm afraid my temporary foil shields would cause the tubes to over heat, plus it's not the best way of doing it. Have you had any experience with this? I wonder if the 100th's are also part of the problem. I really think the talk back is coming from the modulation transformer, which I can live with. I just have to get the feedback out of it. Thanks for your assistance and advice, Rick/K5IZ Mike Sawyer wrote: Rick, The UTC may work so don't discount it. Those I and H model transformers were only about half the size as the D and E models. I can't think of the company that made them but they were substantially different then the earlier models. As always, your mileage may vary. Mod-U-Lator, Mike(y) W3SLK __ 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 -- Bob - NØDGN Bob Bethman - NØDGN \\//\\// (@ @) (@ @) +---oOOo-(_)-oOOo--oOOo-(_)-oOOo---+ | NØDGN AMRadio Manassas, VA|REAL Tube Radio and AM| +---+--+ | Manassas Radio - Home of Homemade Kielbasa Pirogi| +---+--+ | Bob Bethman\\\|/// The absence of a danger | | rbethman(at)comcast.net \\ ~ ~ // signal does *NOT* mean | | (/ @ @ /) that everything is OK | +-oOOo-(_)-oOOo+ | http://home.comcast.net/~rbethman| | 1 BC-61ØI w/BC-614I,1 T-213/GRC-26 w/BC614I 1 '51 Collins R-390A | | SP-600/NR Type 159, Heath DX-60, Apache, Mohawk, SX-101, HT-32A | +---.oooO---Oooo.---.oooO---Oooo.--+ | () () () () | |\ ( ) / \ ( ) / | | \ _) ( _/ \ _) ( _/| +--+ | Amateur Astronomer - Celestron Nexstar 8 | |
Re: [AMRadio] AM Linear Operation
Mike, It might be doable to use a watt meter that either looks at RMS carrier power, and PEP power by the flick of a switch. Since on AM the PEP at 100% plus modulation is ideally 4 times carrier power, the watt meter will show that, say for a 100 watt carrier, you should get 400 watts PEP. If you have a watt meter that can work this way and communicate to you by talking, tones, or whatever, then setting a linear amplifier up into a dummy load is doable. Just advance the RF drive until the four to one ratio drops, and then back off the drive a little from there. If you can follow this approach you will have a linear amp running AM set up better than many others. You will need to juggle the mic gain, drive level, and linear loading to see how much carrier you can transmit while preserving the 1 to 4 ratio, and do so without the visual aid of a scope. This will take some experimentation. Once everything is set, then your antenna must appear identical to your dummy load, or the linear plate loading controls must be readjusted. If this is the case leave the mic gain and drive alone for this final step. Making the antenna appear the same as the dummy load sure simplifies things, and a tuner may be helpful. Regards, Jim WD5JKO --- Mike Duke, K5XU [EMAIL PROTECTED] wrote: I've been reading this AM linear thread with great interest. I currently run a TS570 which gives me no more than 25 watts of carrier, plus a bit more on modulation peaks. I have an unmodified DX60 that I intend to put back in service later this summer after a shack painting project is finished. (No need to move it twice!) Because I enjoy operating, and would like to do so with enough signal to be heard reasonably well on 80 and 40 meters, I too have been considering which linear to run on AM. This discussion of linears on AM has caused me to reason that there is no exact magic combination of carrier drive level and audio level which is guaranteed to produce a cleanly amplified AM signal. For me, at least, this apparent fact is most unfortunate indeed. My signature will give you a hint of the usefulness of a scope in my shack. So, do I sit on my hands and wait for better propogation on the higher bands, or do I continue serving as the pin-drop test for all those restored 75A4's, HQ170's etc? Mike Duke, K5XU American Council of Blind Radio Amateurs __ 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] What about SB-200 with FT-101E?
Hi, I have been using this combination and got some good reports but I have not a reasonable idea of power output. So I would like to have a good estimation from those who are better prepared to do it. Thanks^6 73 de Jose' CT1AXG Date: Fri, 17 Mar 2006 22:03:50 -0500 From: kenw2dtc [EMAIL PROTECTED] Subject: Re: [AMRadio] Amplifier to use with my DX-60 To: Discussion of AM Radio amradio@mailman.qth.net Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; format=flowed; charset=windows-1250; reply-type=response Don K4KYV said: I hear a lot of guys on the air with AM linears, and most of the time they claim to be running way too much carrier for the tubes they are using. I often hear stuff like 200 watts out with a pair of 811A's or 250 watts out with a pair of 813's in g-g. If so, they are cooking the tubes, or else the efficiency is running too high, and they are flat-topping all over the place. I agree with your comments and yes, there is no doubt that those rigs are flat-topping. I've been running linear amps on AM for years and I find that the cleanest, best sounding signal comes from a linear with LOTS OF PLATE DISSIPATION and HEADROOM. In addition, an audio signal generator and an oscilloscope are mandatory to get clean results. Not everyone has this equipment and it is a hobby after all so folks do the best they can. As a rule of thumb I consider the plate dissipation divided by 3 to be a general yardstick for AM linears, some tubes giving a little more and some a little less. In the case of a pair of 3-500Z's I rate them in the 333-350 watt carrier class. So while a pair of 813's can be a wonderful plate modulated rig, as an AM linear they are not worth all the trouble of building them. It seems to me to be a waste of time to build an AM linear with much less than 1000 watts of plate dissipation. Of course if you have a low power rice box and already own some kind of linear, well go ahead, but if one is building an AM linear, more dissipation is better. 73, Ken W2DTC __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
[AMRadio] Use of an oscilloscope to monitor am audio
I have a Tektronix model 453a scope and I would like to know how it can be used to monitor transmitted signals. Do I need extra hardware or an interface of some type to obtain the trapezoid pattern? I know some scopes designed for amateur radio have this feature built in so I wonder if my scope can be used for this? WB5OXQ.
Re: [AMRadio] Amplifier to use with my DX-60
Harry, In the January, 2004 issue of Electric Radio, there is an article on the DX-60. There is a ckt for adding Heising modulation w/ a 6146 and a few parts. It looks easy and simple. Single issues of ER are available. Ya can order on line. The issue also has a brief history of AM modulation methods along with circuits. klc - Original Message - From: Harry Vaught [EMAIL PROTECTED] Date: Friday, March 17, 2006 2:56 pm Subject: Re: [AMRadio] Amplifier to use with my DX-60 Cc: 'Discussion of AM Radio' amradio@mailman.qth.net Thanks to those who replied to my question about plate modulating my DX-60. Amazingly, the conversions sound practical. I was expecting posts which started, First, obtain some unobtainium Thanks, guys. Harry, KT4AE Maryville, Tennessee __ 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] Amplifier to use with my DX-60
Actually, I'm a subscriber and have that issue. How did I miss remembering that when I got the DX-60? Thanks, Harry, KT4AE Maryville, Tennessee [EMAIL PROTECTED] wrote: Harry, In the January, 2004 issue of Electric Radio, there is an article on the DX-60...
RE: [AMRadio] Amplifier to use with my DX-60
Harry, You will need to find a suitable modulation transformer for the impedances, and power levels used. If the amp uses metal 6L6's, consider pathways towards a little higher power, as 25 watts is a little light for this job. I might be wrong but my recollection is that a 6146 is good for 65 watts DC input on AM. Backing that down to 50 watts DC input to better match your PA amp power is another option. You might be able to use another audio output transformer to raise the voice coil impedance back up, but if you do this look at a single ended transformer designed to handle DC current flow (these have gapped cores). There are some in the 25 watt category that audiophiles use, but don't expect a cheap price. Alternatively you could use another push pull output transformer, a choke, and an AC capacitor to shunt the 6146 plate current away from the non-gapped 2nd transformer. The use of back to back transformers is not usually the best choice, but with the limited availability of modulation transformers, the back to back transformer idea has a certain appeal to it. Once these details are worked out, you need to make a mod to disable the modulator when you are not transmitting. You might add a relay and hook that into the transmit PTT circuit. The details on how this goes will depend on the circuitry in your own equipment, and whatever choice you prefer. If you could post the schematic somewhere of that PA amp, maybe the group could offer suggestions on how to adapt it to modulator usage. Regards, Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Harry Vaught Sent: Friday, March 17, 2006 7:13 AM To: Discussion of AM Radio Subject: Re: [AMRadio] Amplifier to use with my DX-60 Ok, tell me this: I have a DX-60A and a 25 watt P-P 6L6 Webster Electric PA amp with a large selection of output impedances. What would I have to do to plate modulate my DX-60? There are obviously greatly varying levels of knowledge out there, and mine is probably below median. Harry, KT4AE Maryville, Tennessee __ 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006
Re: [AMRadio] Amplifier to use with my DX-60
Thanks Jim and to everyone who provided information. I actually asked more out of curiosity, since the subject had been raised, than as an actual likely project. Thanks again to everyone. Jim candela wrote: Harry, You will need to find a suitable modulation transformer...
RE: [AMRadio] Use of an oscilloscope to monitor am audio
Jim, It should work so long as the sweep circuitry has an X:Y position. I use a Tek 465, and it has that option. Now sampling the RF and audio with these scopes needs a little discussion. For RF, I like to make a voltage divider to say take my highest power at WD5JKO at 50 ohms (input to tuner) and divide that voltage to about 10 volts peak (could be 1, or 5). Make the lower divider resistor 50 ohms. Some usage of ohms law, and power formulas are required, but nothing tough here. Then use coax to your scope, BNC-BNC. If the coax is very long, and you worry about line SWR, then terminate the scope input with a 50 ohm BNC Female to BNC male feed through termination adapter. As an alternative, if your SWR will remain low, and the power is below 500 watts, then simply use a coax T and a scope 10X probe. Stick a banana plug into the T with a little piece of wire (1/2 inch) affixed to it so the scope probe can clip on. Use the scope ground clip to the coax cable shield (a small worm drive hose clamp fits nicely on the PL-259 knirled end, and the aligator clip clips to the hanging clamp tang). Another option for some with a Johnson Matchbox as they have a pick-up already included that you can tie your scope into. For the audio, I like to divide that down to about the same 10 volts peak level (could be 1, or 5). For low level modulation all you need is to tap into the audio chain as close to the modulated element as possible, remove any DC, and scale level such that the scope input attenuator can easily handle it. For plate modulation where the plate voltage might be pretty darn high, you need to remove the DC with a suitable capacitor, and divide the audio level way down to the proper level. This might take a bunch of series resistors (limit voltage across each resistor to maybe 500 volts peak), and consider power dissipation per resistor to no more than 50% of the rating. With a high ratio divider you will see phase shift (R-C) increase with increasing audio frequency, and this will corrupt the presented trapezoid. To get around this minimize the capacitive load on the divider, or compensate the divider like is done on a 10X scope probe. Hope this helps, Jim -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Jim Miller WB5OXQ Sent: Saturday, March 18, 2006 11:29 AM To: Discussion of AM Radio Subject: [AMRadio] Use of an oscilloscope to monitor am audio I have a Tektronix model 453a scope and I would like to know how it can be used to monitor transmitted signals. Do I need extra hardware or an interface of some type to obtain the trapezoid pattern? I know some scopes designed for amateur radio have this feature built in so I wonder if my scope can be used for this? WB5OXQ. __ 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006
RE: [AMRadio] Use of an oscilloscope to monitor am audio
Good Morning Jim, Yup, some addional hardware is needed for both a waveform and trapezoidal pattern. Best to get an older ARRL(g) Handbook from the late 1950's early 1960's. The circuits and hardware are descriped there. I can send info, .pdf file, jpegs, and parts list of a little box I built for my cheap $5 hamfest Eico 460. 73's wd8kdg Craig -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Jim Miller WB5OXQ Sent: Saturday, March 18, 2006 9:29 AM To: Discussion of AM Radio Subject: [AMRadio] Use of an oscilloscope to monitor am audio I have a Tektronix model 453a scope and I would like to know how it can be used to monitor transmitted signals. Do I need extra hardware or an interface of some type to obtain the trapezoid pattern? I know some scopes designed for amateur radio have this feature built in so I wonder if my scope can be used for this? WB5OXQ. __ 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] Use of an oscilloscope to monitor am audio
Check out the amfone.net web site. Here's a great and simple RF scope pickup: http://amfone.net/ECSound/K1JJ8.htm You might want to also check out The AM Forums Online AM Handbook: http://amfone.net/Amforum/index.php#14 Tons of great info there and all related to AM operation. Pete, wa2cwa On Sat, 18 Mar 2006 11:29:13 -0600 Jim Miller WB5OXQ [EMAIL PROTECTED] writes: I have a Tektronix model 453a scope and I would like to know how it can be used to monitor transmitted signals. Do I need extra hardware or an interface of some type to obtain the trapezoid pattern? I know some scopes designed for amateur radio have this feature built in so I wonder if my scope can be used for this? WB5OXQ.
Re: [AMRadio] Use of an oscilloscope to monitor am audio
The 453 is limited as to frequency response if I recall correctly, so it may only be useful on the lower bands for RF displays via the horizontal input. If the scope has an X/Y mode, you can go beyond the usual envelope pattern you get from putting RF on the X input... In my professional work with AM, I find you can get a very useful pattern by putting RF on the X input and line-level modulating audio on the Y. It forms an ellipse that closes on 100% negative. I find it easier to see the compression/limiting action as shades of intensity on this waveform. Steve WD8DAS [EMAIL PROTECTED]
Re: [AMRadio] Use of an oscilloscope to monitor am audio
Jim Miller WB5OXQ wrote: I have a Tektronix model 453a scope and I would like to know how it can be used to monitor transmitted signals. Do I need extra hardware or an interface of some type to obtain the trapezoid pattern? I know some scopes designed for amateur radio have this feature built in so I wonder if my scope can be used for this? WB5OXQ. I see that there are already all kinds of answers, but honestly, what I do is just take another antenna outside - perhaps even something as small as a 10m loop (for a 75m antenna) and toss it up on the roof, under the antenna, and just use that to monitor the transmitted signal. You'll see the AM envelope and be able to tell exactly what kind of audio peaks you have, how close you are to pinching off the carrier - once the sweep-rate is set slow enough to see the audio, it's a simple matter of adjusting the volts/div to a level where your carrier consums 2 centimeters (squares) tall. One above, and one below the center line. When audio peaks hit the top of the line of the centimeter/square ABOVE and BELOW the carrier quiescent point, and that co-incides with the negative part of the cycle just at the center-line (-not- to where the carrier is pinched off) then that's 100% modulated. this is a positive-to-negative peak ratio of 2:1 Here's where some of the discussion has been, of late... it's -my- feeling (and a few of the guys here feel the same) that -over- modulation occurs when the negative going part of the audio that modulates the carrier goes 'beyond' the baseline. At that point, you've exceeded the capability of your modulator, and are therefore overmodulating. By allowing the typical male-patterned asymetrical voice peaks to rise to whatever peak they wish, as long as you're not overmodulating beyond 100% Negative, you're not going to cause distortion and splatter, -and- your peaks will be -much- higher. In my case, I've got the capbility of having a positive-to-negative peak ratio of 4:1. do the math.. if a positive-to-negative peak ratio of 2:1 is equivalent of 100% modulation, then the positive peaks must be 4x the carrier level. Must be, because when voltage doubles, current doubles. Therefore, a 100w carrier, 100% modulated with a 2:1 positive-to-negative peak ratio, is producing instantaneous peaks of 400w Peak Envelope Power. If I run my positive-to-negative peak ratio back up to 4:1, with my 100w carrier, my PEP level is 1,600w, *according to the scope*. Who needs a PEP reading watt meter? I've got a -much- better peice of test equipment! -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] What about SB-200 with FT-101E?
I've been using a SB-200 with various rigs (C.E. 100V, Laf. HA-410 (on 10, when 10 was hot), Icom 756 PRO II, Icom IC-706 MKIIG, Johnson Ranger, and Kenwood Twins on AM for the last 15 years. Sometimes I use the Johnson Courier as an alternative to the SB-200. Courier also runs with 572B's. Simple to use, simple to interface, provide an extra fan on top of the SB-200 to exhaust the heat. The SB-200 is a great workhorse. Still using the same 572B's that were put in it in 1969. I generally run the output between 100 and 130 watts. Pete, wa2cwa On Sat, 18 Mar 2006 07:48:02 -0800 (PST) Jose HF Silva [EMAIL PROTECTED] writes: Hi, I have been using this combination and got some good reports but I have not a reasonable idea of power output. So I would like to have a good estimation from those who are better prepared to do it. Thanks^6 73 de Jose' CT1AXG Date: Fri, 17 Mar 2006 22:03:50 -0500 From: kenw2dtc [EMAIL PROTECTED] Subject: Re: [AMRadio] Amplifier to use with my DX-60 To: Discussion of AM Radio amradio@mailman.qth.net Message-ID: [EMAIL PROTECTED] Content-Type: text/plain; format=flowed; charset=windows-1250; reply-type=response Don K4KYV said: I hear a lot of guys on the air with AM linears, and most of the time they claim to be running way too much carrier for the tubes they are using. I often hear stuff like 200 watts out with a pair of 811A's or 250 watts out with a pair of 813's in g-g. If so, they are cooking the tubes, or else the efficiency is running too high, and they are flat-topping all over the place. I agree with your comments and yes, there is no doubt that those rigs are flat-topping. I've been running linear amps on AM for years and I find that the cleanest, best sounding signal comes from a linear with LOTS OF PLATE DISSIPATION and HEADROOM. In addition, an audio signal generator and an oscilloscope are mandatory to get clean results. Not everyone has this equipment and it is a hobby after all so folks do the best they can. As a rule of thumb I consider the plate dissipation divided by 3 to be a general yardstick for AM linears, some tubes giving a little more and some a little less. In the case of a pair of 3-500Z's I rate them in the 333-350 watt carrier class. So while a pair of 813's can be a wonderful plate modulated rig, as an AM linear they are not worth all the trouble of building them. It seems to me to be a waste of time to build an AM linear with much less than 1000 watts of plate dissipation. Of course if you have a low power rice box and already own some kind of linear, well go ahead, but if one is building an AM linear, more dissipation is better. 73, Ken W2DTC
Re: [AMRadio] Use of an oscilloscope to monitor am audio
Geoff et all, That was exactly what I had set up for my former QTH. With a dipole running above and parallel to the roof peak and a long wire alongside the house and parallel to the dipole. Was a great asset for Antenna tuning and monitoring envelope. Of course weather conditions had an effect that made some adjustment necessary but it showed actual radiated signal as good as any remote receiver. Not a replacement for the proper monitor scope but a good compliment and with a diode det fed to a headphone amp could be used as an actual monitor as well. Bill KB3DKS/1
Re: [AMRadio] Amplifier to use with my DX-60
Harry, Can you send me a copy of that article. I have 2 DX60's and collect all the mod info I can find. Healthfully yours, DON W4BWS Don Sanders PO Box 10195 Dothan, AL 36304 [EMAIL PROTECTED] - Original Message - From: Harry Vaught [EMAIL PROTECTED] To: [EMAIL PROTECTED] Cc: Discussion of AM Radio amradio@mailman.qth.net Sent: Saturday, March 18, 2006 11:40 AM Subject: Re: [AMRadio] Amplifier to use with my DX-60 Actually, I'm a subscriber and have that issue. How did I miss remembering that when I got the DX-60? Thanks, Harry, KT4AE Maryville, Tennessee [EMAIL PROTECTED] wrote: Harry, In the January, 2004 issue of Electric Radio, there is an article on the DX-60... __ 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] Use of an oscilloscope to monitor am audio
[EMAIL PROTECTED] wrote: Geoff et all, That was exactly what I had set up for my former QTH. With a dipole running above and parallel to the roof peak and a long wire alongside the house and parallel to the dipole. Was a great asset for Antenna tuning and monitoring envelope. Of course weather conditions had an effect that made some adjustment necessary but it showed actual radiated signal as good as any remote receiver. Not a replacement for the proper monitor scope but a good compliment and with a diode det fed to a headphone amp could be used as an actual monitor as well. Bill KB3DKS/1 You know... there are devices that produce a tone that rises or lowers in pitch, depending on how much power they're exposed to. Useful aids for tuning amps for max, after SWR has been tuned for a minimum, for someone who can't see the meters. for those of us who are non-visualy-handicapped, the external antenna, scope and a crystal detector would be a much -greater- aid to maintaining a clean AM signal, than relying solely on a pep reading watt-meter (which is limited by the how fast the movement of the meter is, in the first place) -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Use of an oscilloscope to monitor am audio
Jim I have a Tek 465M that I use. I also have a tuner with a built in balun that I do not use. I use the tuner with coax when operating off the resonance of my antenna. My scope and probes are good to 100 Mc and provide enough bandwidth to monitor up to 29 Mc. If your 453's bandwidth is less, you won't be able to go as high. So I take my 10:1 probe and attach to the output of the balun terminals. One to the ground clip and the other to the probe. That provides enough isolation to give a waveform display. The waveform is very difficult to follow as to assure 100% modulation. To be accurate, one should use the trapezoidal pattern. The peaks and valleys of a waveform cannot be seen accurately on a scope unless you have a storage scope. Others have suggested means of building a sampler for this purpose, and I thought I would mention another way. 73 Jim W5JO I have a Tektronix model 453a scope and I would like to know how it can be used to monitor transmitted signals. Do I need extra hardware or an interface of some type to obtain the trapezoid pattern? I know some scopes designed for amateur radio have this feature built in so I wonder if my scope can be used for this? WB5OXQ.
[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
Re: [AMRadio] Kenwood TS-820 mod for am
Bill Fondren wrote: 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 __ that was John/WA5BXO and he said: I suppose it is also preference. BJ and I modified the Kenwood TS820 to full double sideband and it runs about 10-20 watts carrier output in that mode we drive and SB200 modified with a switch to kick in extra bias when we use in on AM. It puts out about 75-80 watts carrier with good modulation characteristics. So the combo is equivalent to a DX100 with maybe better audio. As to HOW he did it, you'll have to ask him. -- 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] Modulator feedback
, The UTC may work so don't discount it. Those I and H model transformers were only about half the size as the D and E models. I can't think of the company that made them but they were substantially different then the earlier models. The potted versions are made by Chicago Transformer Co. They are indeed much smaller than the older end-bell model like what is used in the E model. I suppose they work OK, because I have not heard a lot of complaints about blowing them, but I am still amazed at how TINY those things are. Don K4KYV
[AMRadio] Re:Re: Use of an oscilloscope to monitor am audio
Geoff et al, A possible easy circuit to implement could be what is used for audio peak indication in most good recorders and mixing consoles. It responds to the slightest DC present in a sampled audio signal. Not the threashold comparator type of circuit but a true clipping indicator. I have worked on audio gear where the flat top wasn't even noticable on the scope but the circuit was triggering. That could sound a chirp or other tone for indication. My complete monitoring setup was a Philips 10 mhz dual trace O Scope that for receive, the triggering channel was the receiver audio out and the other channel was the IF out. On transmit, controlled by the plate switch of the VK II, a set of coax BNC relays with suitable in line attenuators to match levels would give me the mic audio to the triggering channel and the long wire rf to the other channel. This way the scope was always triggered from the audio and any phase shift or flat top/clipping was clearly visable. This was used for 40 and 75 meters. Another relay could switch in the output from my Heath Cantenna dummy load for testing and tune up. Everything was controlled from the antenna relay plug on the rear of the transmitter with the 120 vac output from that going into a stepdown transformer to whatever voltage was needed by the coax relays. It was the start of a much more complex monitoring system that was never carried out to include other tranmitters and receivers since I moved before finishing it. Bill KB3DKS/1
Re: [AMRadio] Use of an oscilloscope to monitor am audio
I just checked the specs on my scope and it says it is a dual channel dual trace with X-Y capability frequency range DC to 60 Mhz. - Original Message - From: Jim Wilhite [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Saturday, March 18, 2006 3:25 PM Subject: Re: [AMRadio] Use of an oscilloscope to monitor am audio Jim I have a Tek 465M that I use. I also have a tuner with a built in balun that I do not use. I use the tuner with coax when operating off the resonance of my antenna. My scope and probes are good to 100 Mc and provide enough bandwidth to monitor up to 29 Mc. If your 453's bandwidth is less, you won't be able to go as high.
[AMRadio] Voltage regulator
This last week I built a 12 volt and 24 volt power supply in one small box to power various relays around the shack. Well, the 12 volt turned out to be 16 volts, and the 24 volt is 36 volts. Even loaded the voltage is high. I've done quite a bit of Googling on the subject of three-terminal voltage regulators, but have found nothing that had actual component values that would be pertinent to my needs. Also saw a three-terminal using a pass-transistor. Again, no actual component values. I'd like to be able to get the voltages down to more nearly what I need so that I don't burn out a relay. Perhaps 14 volts and 26 to 28 volts, at an amp or so. My knowledge of solid-state devices is close to zero. Anyone have some ideas? 73, Barrie, W7ALW
RE: [AMRadio] DX60 modulator chassis ready to go
I would build a modulator using a pair of KT88 or KT90 tubes, multi match mod transformer, drive the grids of the KT88 tubes with a HIFI amp. The KT90 pair is good for about 140 watts of audio in AB1 (no driving power). 809's or 811's in class b would also work. Build a nice modulator with a multi match mod trans and you can modulate anything with it. A thordarson 300 watt multi match would do well... You could have fun with this project, make it mike input (D104 or a low Z mike) with tone controls, or the easy way of the line level equipment (berrenger ultra voice) and a power amp. A while ago, I found a 25 watt dual channel power amp made by symetrix for under $100.00 at a trading post place, its 1 inch high rack mount, along with the 1 inch high berrenger, it makes for a very small clean audio setup. 25 watts is way more then enough to drive all the modulator grids I have, the 4x150a's, the 811a's, etc. You get eq, compression, noise gate, line or mike level input, and with the twist of a few knobs, can restrict the audio down on the low and/or high end, or open it up to full fidelity. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Lyles Sent: Saturday, March 18, 2006 5:56 PM To: amradio@mailman.qth.net Subject: [AMRadio] DX60 modulator chassis ready to go This modulator is not exactly like the 1952 nor the 1959 ARRL HB 807 modulators. It appears to be a class B modulator, not AB1 or AB2. It has 5 tubes, three are 12AU7 and two are 807. The input audio is conventional mike preamp and audio stage, using both halves of first 12AU7 with a gain pot to the grid of the the second 12AU7. It appears to be connected with both triodes in parallel, driving a UTC S2 single ended to push pull 2:1 driver transformer. The ends of the secondary each drive a grid of the third 12AU7. Plates are hard connected to B+ and they are configured as cathode followers. These drive the grid and screen of triode connected 807s. There is no bias supply at all, the 807s being direct coupled to the cathodes of 12AU7 triode sections, and the grids of those are through the S2 secondary to ground. I suppose some self bias might develop on the 807 grids. Output transformer is a Stancor A3892 30 Watt polypedance. There is an octal socket to bring all the power in (filament and B+1 and B+2) and a mike connector, and a volume control. Entire chassis is 9.5 inches long, 4 inches wide, and about 7.5 inches tall to the plate caps on the 807s. It is dirty but there are only a few caps that might need replacing if they are leaky. Has anyone seen this particular design commercially made years ago, or in any articles? It appears quite compact, and with the cathode followers to the 807s, reminds me of the audio lineup of a Gates BC1G, with 807s driving 833s that way. I am asking $80 plus S/H for this thing with all tubes in it. __ 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] Voltage regulator
Barrie, that's a pretty extreme voltage difference. You should not be having this problem. I assume there is a basic mistake somewhere. Do you have the in-out pin connections correct? Do you have the ground pin grounded? You can get data sheets for most regulators from the manufacturers or from Digi-Key. At Digi-Key you do a part search, select a part number, and then click on the highlighted part number in the Technical/Catalog Information field, click on the datasheet, and you get a datasheet in pdf form. Bacon, WA3WDR - Original Message - From: Barrie Smith [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Saturday, March 18, 2006 7:46 PM Subject: [AMRadio] Voltage regulator This last week I built a 12 volt and 24 volt power supply in one small box to power various relays around the shack. Well, the 12 volt turned out to be 16 volts, and the 24 volt is 36 volts. Even loaded the voltage is high.
Re: [AMRadio] Voltage regulator
Barrie, I guess you are using a transformer, rectifier, and filter capacitor. The capacitor is charging up to the peak value of the AC waveform. You could go all out and make nice DC with regulators, and such, but for relays do you really need that? If your rectifier is full wave then just remove the capacitor filter, and the rectified DC will likely be fine to energize a DC Jim: I knew I'd find someone smarter than I here! That's exactly what's happening, but I didn't know one could run without the cap. It helps to put a diode across the coil (cathode to + end) to suppress the back EMF when you turn off the relay. I have done that! TNX, Barrie, W7ALW Jim WD5JKO -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Barrie Smith Sent: Saturday, March 18, 2006 6:47 PM To: Discussion of AM Radio Subject: [AMRadio] Voltage regulator This last week I built a 12 volt and 24 volt power supply in one small box to power various relays around the shack. Well, the 12 volt turned out to be 16 volts, and the 24 volt is 36 volts. Even loaded the voltage is high. I've done quite a bit of Googling on the subject of three-terminal voltage regulators, but have found nothing that had actual component values that would be pertinent to my needs. Also saw a three-terminal using a pass-transistor. Again, no actual component values. I'd like to be able to get the voltages down to more nearly what I need so that I don't burn out a relay. Perhaps 14 volts and 26 to 28 volts, at an amp or so. My knowledge of solid-state devices is close to zero. Anyone have some ideas? 73, Barrie, W7ALW __ 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006 __ 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] Voltage regulator
If its just relays, you can just add say a 5 ohm resistor on the output. measure the voltage with the relays pulled in, load/no load voltage will vary a lot... Or, if its DC, reduce the filter cap a lot, you don't need filtering for relays, and the size of the cap has a big impact on the loaded voltage you get out. Or, add choke input, Or, half wave rectify the thing, gives half the voltage output (use a big cap), 8 and 18 volts may pull the relays in fine. The three term regulators are mostly good for 1.5 amps, there are adjustable ones and fixed ones, I don't think the fixed ones have any additional parts...input, output, ground? Brett N2DTS This last week I built a 12 volt and 24 volt power supply in one small box to power various relays around the shack. Well, the 12 volt turned out to be 16 volts, and the 24 volt is 36 volts. Even loaded the voltage is high. I've done quite a bit of Googling on the subject of three-terminal voltage regulators, but have found nothing that had actual component values that would be pertinent to my needs. Also saw a three-terminal using a pass-transistor. Again, no actual component values. I'd like to be able to get the voltages down to more nearly what I need so that I don't burn out a relay. Perhaps 14 volts and 26 to 28 volts, at an amp or so. My knowledge of solid-state devices is close to zero. Anyone have some ideas? 73, Barrie, W7ALW __ 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 feedback
I agree, they are very small for a 250 watt transformer. I made a few more adjustments such as line voltage and tightening up the old E model tranny. Hopefully, when I get the back on it will be usable now. I sure appreciate all of the suggestions, advice and experience I have received here. Rick/K5IZ Donald Chester wrote: , The UTC may work so don't discount it. Those I and H model transformers were only about half the size as the D and E models. I can't think of the company that made them but they were substantially different then the earlier models. The potted versions are made by Chicago Transformer Co. They are indeed much smaller than the older end-bell model like what is used in the E model. I suppose they work OK, because I have not heard a lot of complaints about blowing them, but I am still amazed at how TINY those things are. 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] Voltage regulator
I took the caps (100MFD) out of the circuit and, while the voltage dropped quite a bit, a couple of the relays buzzed quite loudly. A couple of others didn't. It was mentioned that lower capacitor caps may be a partial cure. What capacitance would be suggested, one MFD, 10 MFD? I put the 1000 MFD back into the 12 (15) volt supply, and then tried the resistor in series. I did not find anything in the range of 5 ohms, but I did find a 5 watt, 12 ohm resistor. Under the load of one relay the voltage dropped to 9.75 volts, so I think the suggested value of 5 ohms would be very close to correct. 73, Barrie, W7ALW
Re: [AMRadio] Amplifier to use with my DX-60
In a message dated 3/18/06 9:41:29 AM, [EMAIL PROTECTED] writes: Actually, I'm a subscriber and have that issue. How did I miss remembering that when I got the DX-60? Thanks, Harry, KT4AE Maryville, Tennessee [EMAIL PROTECTED] wrote: Harry, In the January, 2004 issue of Electric Radio, there is an article on the DX-60... Also, see ER# 133 (May 2000) and 140 (Jan. 2001) Dennis D. W7QHO Glendale, CA
Fwd: [AMRadio] Amplifier to use with my DX-60
Re: [AMRadio] Amplifier to use with my DX-60
I would be interested in that Dennis. TNX. Mod-U-Lator, Mike(y) W3SLK - Original Message - From: [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Saturday, March 18, 2006 11:07 PM Subject: Re: [AMRadio] Amplifier to use with my DX-60 For a simple and very effective modulator for rigs in this power class that doesn't require increasingly hard to find modulation iron, let me recommend a Heising circuit originally described in the April 1955 issue of Radio and Television News and revisited in ER #91, Nov. 1996. The scheme utilizes a clever bias shifting scheme to squeeze 30 - 40 watts of audio out of a single 807 modulator tube. No transformer required, only a 10 H filter choke. Won't modulate 100% in the negative direction (in common with other Heising circuits) but comes so close you can't tell the difference. The original author called it a Reference Shift Modulator. Can provide more information if anyone's interested. 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 AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb
