Re: [AMRadio] BW 5100B
I have the same downward modulation in my Icom 746 and sure wish I could tune to the opposite side of the dip in final current to fix it, hi hi! On 11 Oct 2004 at 0:39, [EMAIL PROTECTED] wrote: Try tuning to the opposite side of the dip in plate current. 73, John, W4AWM __ 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] 40m AM Nets
, too, am interested in AM nets. I have such low power and inefficient antenna I hesitate to mix it up with the big guns. 73, Ed Richards K6UUZ Ed you would be VERY pleasantly surprised what you can do on 40m AM on a Saturday morning with 30 watts to a dipole! Out to 300-500 miles you will get plenty of S9 reports. I'd like to see 7.160 get re-vitalized for Saturday morning AM operation. Back in the Day, there was W5MEU, W5PYTAA5YT (Was that Floyd's call?) W9(???)Paul, in Chicago, more.. 40m, AM, 7.160, Saturday Mornings. 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] 40m AM Nets
Thanks, Brian. I will give it a try. 73, Ed Richards K6UUZ On Wed, 13 Oct 2004 06:43:15 -0400 Brian Carling [EMAIL PROTECTED] writes: On 11 Oct 2004 at 10:56, Edward B Richards wrote: , too, am interested in AM nets. I have such low power and inefficient antenna I hesitate to mix it up with the big guns. 73, Ed Richards K6UUZ Ed you would be VERY pleasantly surprised what you can do on 40m AM on a Saturday morning with 30 watts to a dipole! Out to 300-500 miles you will get plenty of S9 reports. Brian __ 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] 40m AM Nets
I think I will try a couple of the 40 meter AM nets this weekend with my 100 watt Apache. I sometimes listen to 75 meter AM during the evening, and all I hear are the same big guns in a rountable and I don't know if they welcome low power outsiders. 73, Don K2FY -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Edward B Richards Sent: Wednesday, October 13, 2004 10:48 AM To: [EMAIL PROTECTED]; amradio@mailman.qth.net Subject: Re: [AMRadio] 40m AM Nets Thanks, Brian. I will give it a try. 73, Ed Richards K6UUZ On Wed, 13 Oct 2004 06:43:15 -0400 Brian Carling [EMAIL PROTECTED] writes: On 11 Oct 2004 at 10:56, Edward B Richards wrote: , too, am interested in AM nets. I have such low power and inefficient antenna I hesitate to mix it up with the big guns. 73, Ed Richards K6UUZ Ed you would be VERY pleasantly surprised what you can do on 40m AM on a Saturday morning with 30 watts to a dipole! Out to 300-500 miles you will get plenty of S9 reports. Brian __ 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] 40m AM Nets
I'd like to see 7.160 get re-vitalized for Saturday morning AM operation. Back in the Day, there was W5MEU, W5PYTAA5YT (Was that Floyd's call?) W9(???)Paul, in Chicago, more.. 40m, AM, 7.160, Saturday Mornings. 73 = Best Regards, -Geoff/W5OMR Currently there is a group operating on 7.160 Saturday and Sunday afternoons, usually about 2:00 PM or so, Central Time. Some stations are in MS, LA, TX and AL. Most run moderate power and I hear them in Sulphur, OK just fine when the sidebanders don't get too close. 73 Jim de W5JO __ 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] BW 5100B
With most of the current transceivers, especially Icom, reducing power output or reducing audio, does not change this anomaly in the AM position. Diddling with the internal ALC adjustments would reduce the problem when operating AM. Adding external voltage to the ALC pin, available on one of the rear ACC connectors, will override the internal voltage and also works. Going directly into the DSP modulator, available on one of the rear ACC connectors on some rigs also helps, and also eliminates all the front end mike processing that contributes to poor/fair/average AM audio. Pete, wa2cwa On Wed, 13 Oct 2004 07:44:23 -0400 Brett gazdzinski [EMAIL PROTECTED] writes: That's because you are hitting the alc circuit on mod peaks. You would have to reduce your power output, reduce the audio, or adjust the alc to a higher value. I notice the effect on some guys running AM on rice boxes, its often quite noticeable on the s meter. That's why most run about 20 watts of carrier or less and go light on the audio. My guess would be that adjusting the alc circuit to a higher value will work good on AM, allowing the tips of the peaks to pass without invoking the alc, but would degrade ssb service since they use the alc as a compressor. Power output goes up, so you have to watch out, but most radios have some extra reserve built in for long rtty or fm transmissions. It just always rubbed me the wrong way to spend $3000.00 for some modern wonderbox and get a massive 20 watts out. Brett N2DTS -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brian Carling Sent: Wednesday, October 13, 2004 6:34 AM To: Discussion of AM Radio Subject: Re: [AMRadio] BW 5100B I have the same downward modulation in my Icom 746 and sure wish I could tune to the opposite side of the dip in final current to fix it, hi hi! On 11 Oct 2004 at 0:39, [EMAIL PROTECTED] wrote: Try tuning to the opposite side of the dip in plate current. 73, John, W4AWM Speed up your surfing with Juno SpeedBand. Now includes pop-up blocker! Only $14.95/ month - visit http://www.juno.com/surf to sign up today!
Re: [AMRadio] BW 5100B Modulation Update
Tom, Try a new rectifier tube if you have one and see what you get. Easy way to check capacitors is to tack a new one in parallel with the hv filter cap and see if you get any improvement. Does the 5100 have a meter position for modulator plate current? If so what is it doing. If you have the wrong impedance taps on the mod transformer, the modulators may be drawing much more current than they should. Too high an impedance tap into a low impedance final load will make the modulators draw very heavy current. 73 Gary K4FMX Tom Elmore wrote: The caps are the first thing I should have checked and there is a good possibility they are dried up except I don't hear any hum in the audio when monitoring on the receiver. Also I can make at least 125 watts carrier and don't see much of a voltage drop on B+ when I run carrier only. -Tom - Original Message - From: George Pritchard [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Wednesday, October 13, 2004 8:46 AM Subject: RE: [AMRadio] BW 5100B Modulation Update Tom, It seems to me that the capacitor bank for the 600 volts is not working. Look at the B+ with a scope, and you may see the B+ drop at the audio rate. A stiff capacitor bank will show no audio waveform on the B+. If I'm right, the caps are died out. Is there any trace of Hum on the dead carrier? George AB2KC -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom Elmore Sent: Wednesday, October 13, 2004 12:35 PM To: amradio@mailman.qth.net Subject: [AMRadio] BW 5100B Modulation Update Now that I have had some time to troubleshoot the BW 5100B modulation here is what I found. The B+ is around 600 volts with no modulation and I as start to modulate and watch the scope when it reaches about 50% modulation the B+ drops from 600 to around 400 volts. I changed the final and modulator 6146 tubes and see the same results. The original modulation transformer has been replaced with a Chicago Standard Transformer Corporation # A-3891. When I remove B+ to the final's and terminate the modulation secondary into a resistive load of about 6k ohms I still see a significant drop in B+ as I start to bring modulation up. I don't have the original mod transformer and the manual I have doesn't say what the impedance should be. I have tried various other tap settings on the transformer secondary and don't see much of an improvement in reducing the amount of voltage drop. I wonder if it is possible that this mod transformer just will not work with this unit. Anyone have experience with mod transformers using 6146's as finals and modulators? Thank You Tom Elmore KA1NVZ Anchorage Alaska __ 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] 40m AM Nets?
Yes I have I know them very well -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Steve McDonald Sent: Wednesday, October 13, 2004 9:27 AM To: Discussion of AM Radio Subject: Re: [AMRadio] 40m AM Nets? I am in Minden NV near Reno Brad - have you been up to visit the Radio Museum in Virginia City yet? Steve / VE7SL __ 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] BW 5100B Modulation Update
Yes there is a plate current position and it shows a definite rise in current with modulation. There are dual 5U4's in the supply feeding the finals and modulator and I swapped them both out with the same results. I am leaning towards Gary suggestion that there is an impedance mismatch causing excessive current draw. Does anyone have a 5100B or know what the impedance of the primary and secondary should be. I will try another set of caps this evening when I get home there are 2 , 40uf in series on the B+ line. - Original Message - From: Gary Schafer [EMAIL PROTECTED] To: Discussion of AM Radio amradio@mailman.qth.net Sent: Wednesday, October 13, 2004 10:29 AM Subject: Re: [AMRadio] BW 5100B Modulation Update Tom, Try a new rectifier tube if you have one and see what you get. Easy way to check capacitors is to tack a new one in parallel with the hv filter cap and see if you get any improvement. Does the 5100 have a meter position for modulator plate current? If so what is it doing. If you have the wrong impedance taps on the mod transformer, the modulators may be drawing much more current than they should. Too high an impedance tap into a low impedance final load will make the modulators draw very heavy current. 73 Gary K4FMX Tom Elmore wrote: The caps are the first thing I should have checked and there is a good possibility they are dried up except I don't hear any hum in the audio when monitoring on the receiver. Also I can make at least 125 watts carrier and don't see much of a voltage drop on B+ when I run carrier only. -Tom - Original Message - From: George Pritchard [EMAIL PROTECTED] To: 'Discussion of AM Radio' amradio@mailman.qth.net Sent: Wednesday, October 13, 2004 8:46 AM Subject: RE: [AMRadio] BW 5100B Modulation Update Tom, It seems to me that the capacitor bank for the 600 volts is not working. Look at the B+ with a scope, and you may see the B+ drop at the audio rate. A stiff capacitor bank will show no audio waveform on the B+. If I'm right, the caps are died out. Is there any trace of Hum on the dead carrier? George AB2KC -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom Elmore Sent: Wednesday, October 13, 2004 12:35 PM To: amradio@mailman.qth.net Subject: [AMRadio] BW 5100B Modulation Update Now that I have had some time to troubleshoot the BW 5100B modulation here is what I found. The B+ is around 600 volts with no modulation and I as start to modulate and watch the scope when it reaches about 50% modulation the B+ drops from 600 to around 400 volts. I changed the final and modulator 6146 tubes and see the same results. The original modulation transformer has been replaced with a Chicago Standard Transformer Corporation # A-3891. When I remove B+ to the final's and terminate the modulation secondary into a resistive load of about 6k ohms I still see a significant drop in B+ as I start to bring modulation up. I don't have the original mod transformer and the manual I have doesn't say what the impedance should be. I have tried various other tap settings on the transformer secondary and don't see much of an improvement in reducing the amount of voltage drop. I wonder if it is possible that this mod transformer just will not work with this unit. Anyone have experience with mod transformers using 6146's as finals and modulators? Thank You Tom Elmore KA1NVZ Anchorage Alaska __ 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] BW 5100B Modulation Update
Yes there is a plate current position and it shows a definite rise in current with modulation. There are dual 5U4's in the supply feeding the finals and modulator and I swapped them both out with the same results. I am leaning towards Gary suggestion that there is an impedance mismatch causing excessive current draw. Does anyone have a 5100B or know what the impedance of the primary and secondary should be. I will try another set of caps this evening when I get home there are 2 , 40uf in series on the B+ line. finding out what the final Z is, is as simple as using ohms law (close enough in this case) where R(or Z, if you prefer) of the final is equal to Voltage over Current. R=Ep/Ip. so, given that the Ep is 600VDC, and I'm guessing that Ip would be around 225mA R=600/0.225 R= (around) 2.7kOhms. Kinda low, actually. You'd need a modulater Z of around 2k. Sounds kinda like a 1:1.4 turns ratio is what's needed. 73 = Best Regards, -Geoff/W5OMR
Re: [AMRadio] BW 5100B Modulation Update
Hi Tom, The A-3894 rating was 120W, the A-3893 rating was 60W. I am not sure what the power rating of the 3891 is. I'll assume it is good for 60W or more. What kind of current is the modulator drawing? A mod transformer with some shorted turns could cause the modulator current to be very high for a moderate percentage of modulation. The 600 volt B+ line could be pulling down because of this. It's quite common for an old mod transformer to be shorted and draw way too much current, and not be able to fully modulate the transmitter anyway. It could also be mismatched in such a way as to show a very low impedance to the modulator tubes, resulting in high mod current. If you disconnect the transformer and put 6.3VAC from plate to plate, you should see about 3 to 6VAC on the output side. If you are in doubt as to the tap configuration, measure the voltages and write it all down. Look for the highest voltages... connect the full windings, and try again, etc. If a mod transformer has split windings, make sure you hook them up in the proper polarity. Measure secondary voltage with 6.3VAC across the whole primary, and then measure secondary voltage with the 6.3VAC from CT to either end. You should get twice as much secondary output voltage with the 6.3V from CT to one end. If the secondary winding is split, make sure you see two times as much voltage from end-to-end of the secondary as you see from the CT to either end. Ultimately, you want a full-primary to secondary voltage ratio between 2:1 and 1:1. One winding will usually have more turns than the other. Generally you want the largest winding on the primary side, and the smaller winding on the secondary side (although this is not true for ultra-modulation). I have done best to use the full primary, and experiment with taps on the secondary. 2:1 voltage is 4:1 impedance. 1:1 voltage is 1:1 impedance. As KYV Don pointed out, the lower this ratio, the more modulation you will get, but the lower your modulator load impedance will be, and therefore the higher the modulator current will be for a given output power. 4:1 impedance won't give you 100% mod, while 1:1 could give you about 150% if the tubes are up to it. Typical commercial amateur transmitters used about a 3:1 or 4:1 impedance ratio so the modulation would voltage-limit at about 100%. That would be a voltage ratio of about 1.7:1 to 2:1. So if you put 6.3VAC on the full primary, you should get about 3.5V on the secondary. But that's just a starting point - when you get it all together, you probably want more like 6V on the secondary in this test, which ought to give you about 150% modulation capability. If you know the transformer is OK, you can put 120V AC on it and measure more easily, but 120V is dangerous if you may be connected to the wrong taps, etc. If your taps seem ok, but mod percentage is low, try 120VAC through a 25 watt light bulb to the full primary, with no load on the secondary. If the bulb lights up, you have a shorted transformer. Bacon, WA3WDR - Original Message - From: Tom Elmore [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Wednesday, October 13, 2004 12:34 PM Subject: [AMRadio] BW 5100B Modulation Update Now that I have had some time to troubleshoot the BW 5100B modulation here is what I found. The B+ is around 600 volts with no modulation and I as start to modulate and watch the scope when it reaches about 50% modulation the B+ drops from 600 to around 400 volts. I changed the final and modulator 6146 tubes and see the same results. The original modulation transformer has been replaced with a Chicago Standard Transformer Corporation # A-3891. When I remove B+ to the final's and terminate the modulation secondary into a resistive load of about 6k ohms I still see a significant drop in B+ as I start to bring modulation up. I don't have the original mod transformer and the manual I have doesn't say what the impedance should be. I have tried various other tap settings on the transformer secondary and don't see much of an improvement in reducing the amount of voltage drop. I wonder if it is possible that this mod transformer just will not work with this unit. Anyone have experience with mod transformers using 6146's as finals and modulators? Thank You Tom Elmore KA1NVZ Anchorage Alaska __ 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] BW 5100B Modulation Update
Tom - if that's an A-3891, it isn't enough for a pair of 6146s. It's rated for 15 watts as I feared. http://www.amwindow.org/tech/htm/modtran/stancor/stancor.htm (Stancor and Chicago Standard appear to be the same company) But if it's really an A-3894 with worn paint, then you may be in luck. Bacon, WA3WDR - Original Message - From: Tom Elmore [EMAIL PROTECTED] To: amradio@mailman.qth.net Sent: Wednesday, October 13, 2004 12:34 PM Subject: [AMRadio] BW 5100B Modulation Update Now that I have had some time to troubleshoot the BW 5100B modulation here is what I found. The B+ is around 600 volts with no modulation and I as start to modulate and watch the scope when it reaches about 50% modulation the B+ drops from 600 to around 400 volts. I changed the final and modulator 6146 tubes and see the same results. The original modulation transformer has been replaced with a Chicago Standard Transformer Corporation # A-3891. When I remove B+ to the final's and terminate the modulation secondary into a resistive load of about 6k ohms I still see a significant drop in B+ as I start to bring modulation up. I don't have the original mod transformer and the manual I have doesn't say what the impedance should be. I have tried various other tap settings on the transformer secondary and don't see much of an improvement in reducing the amount of voltage drop. I wonder if it is possible that this mod transformer just will not work with this unit. Anyone have experience with mod transformers using 6146's as finals and modulators? Thank You Tom Elmore KA1NVZ Anchorage Alaska __ 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] 40m AM Nets
If you are in the Southeast states try 7290 around 10 AM or 11 AM with us! Thanks - Bry, AF4K Orlando, FL area On 13 Oct 2004 at 11:13, Schichler, Don wrote: I think I will try a couple of the 40 meter AM nets this weekend with my 100 watt Apache. I sometimes listen to 75 meter AM during the evening, and all I hear are the same big guns in a rountable and I don't know if they welcome low power outsiders. 73, Don K2FY -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Edward B Richards Sent: Wednesday, October 13, 2004 10:48 AM To: [EMAIL PROTECTED]; amradio@mailman.qth.net Subject: Re: [AMRadio] 40m AM Nets Thanks, Brian. I will give it a try. 73, Ed Richards K6UUZ On Wed, 13 Oct 2004 06:43:15 -0400 Brian Carling [EMAIL PROTECTED] writes: On 11 Oct 2004 at 10:56, Edward B Richards wrote: , too, am interested in AM nets. I have such low power and inefficient antenna I hesitate to mix it up with the big guns. 73, Ed Richards K6UUZ Ed you would be VERY pleasantly surprised what you can do on 40m AM on a Saturday morning with 30 watts to a dipole! Out to 300-500 miles you will get plenty of S9 reports. Brian __ 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] Mod xmfr
I have no information on the 813's distortion when used that way. Have you found any curves showing the effect of screen voltage on plate current? The linearity of those would tell something. Alot of external things affect distortion, the modulation xfmr is real important. Patrick From: Brett gazdzinski [EMAIL PROTECTED] Subject: RE: [AMRadio] Mod xmfr One thing I don't like about doing different things with tubes is there is no real info on running 813's triode connected. What's the distortion values? I have a Gonset G76 that uses zero bias and drives the screen grid of a pair of 6dq6 tubes as modulators. I don't think its real clean. Brett N2DTS
[AMRadio] RE: BW 5100B Modulation Update
My book online says that the A-3891 is a 15 watt transformer. Could you be overloading and saturating it to the point where it is no longer transferring power, but just eating it? Seems quite small for the application. http://208.190.133.201/old_iron/STANCOR_140H_MAY1948_WEB/015.jpg -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom Elmore Sent: Wednesday, October 13, 2004 12:35 PM The original modulation transformer has been replaced with a Chicago Standard Transformer Corporation # A-3891. Thank You Tom Elmore KA1NVZ Anchorage Alaska
Re: [AMRadio] BW 5100B Modulation Update
What are the dimensions? 3 3/16 H by 2 5/8 W by 2 7/8 D = A-3891
