RE: [AMRadio] Modulator design needed
No. The KT88's are AB1 so a phaze inverter does the job. A long time ago I gave the driver transformer away, as I had a bunch of 32V's. The mike is a D104, it goes into a 6SL7, the filaments run off DC, the 2nd stage of the 6SL7 is a voltage amp, then into the 6SN7 phase splitter circuit. I have the phase splitter circuit unbalanced a bit to give more positive modulation. The feedback circuit acts a bit like a tone control, less feedback gives a brighter sound. It sounds ok for a D104, and I get plenty of audio on the carrier. I had to re-do the screen supply for the 4D32, and take some modulated and unmodulated voltage to feed it. Brett > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of John > Coleman ARS WA5BXO > Sent: Sunday, March 26, 2006 10:02 PM > To: 'Discussion of AM Radio' > Subject: 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.. > >
RE: [AMRadio] Modulator design needed
Here is another link for the Dynaco catalog: http://www.the-planet.org/pdf/transformer.pdf This has some KT-88 circuits -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 3/24/2006
RE: [AMRadio] Switching between multiple rigs
I tell you what guys Glen K9STH built me a switching unit that is beyond words. Probably a little over kill but works great...Changes rigs feeds an amp mutes receivers ect ect... Contact Glen on the group he may be able to build more... Neat little box... Bob W1PE -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brett gazdzinski Sent: Sunday, March 26, 2006 6:43 PM To: 'Mike Duke, K5XU'; 'Discussion of AM Radio' Subject: RE: [AMRadio] Switching between multiple rigs Here is what I did: I found a small rack mount box from work, and put lots of coax connectors on it, a bunch of terminal strips (screw type), and inside I have a bunch of rotary switches of various types. Its about 5 inches high, rack mount, front is painted black and the switches are labeled. I have from left to right, mod monitor sample control (high voltage variable capacitor, about 50 pf) Receiver selector switch, 7 positions, AC switch, 7 positions, this connects to various transmitters, Antenna switch, 4 position (big heavy duty ceramic switch) Transmitter antenna selector switch, 4 position heavy duty ceramic. Inside is a big open contactor mounted on rubber isolators, that is my T/R relay. I can pick any antenna (or dummy load), any receiver, any transmitter, and which transmitter keys the T/R relay. I also have a pair of coax connectors to go to the watt meter and or tuner, no matter what selections are made. I also have two small relays to do muting and so on, about 6 normally open, common, and normally closed contacts out the back on screw terminals. For the audio, I use one setup, one mike into the berringer, the berringer goes to a dual output audio amp that drives 2 modulators at once. One side goes to my pair of 813's rig, the other goes to the push pull 812a transmitter. The 32v3 uses its own D104. Any and all receivers have audio line level outputs going to a rack mount Marantz audio amp, 5 inputs, line in and outs, bass, mid and treble controls, headphone jack, low and high filters, etc. into one nice 3 way speaker. I use an icom 756 pro to excite the transmitters, it has two antenna outputs and a separate receive input, so all I have to do is push a button there. its keyed by one of the relay contacts in my switch box. I don't remember what I did with the push to talk setup, I have a small DPDT switch on the mike base that runs to both big transmitters to key them. This all adds up to a mess of wires and cables, but allows me to hook up anything, and select it once its hooked up. I can switch between transmitters or receivers in 2 seconds, do A/B/C antenna switches, all from one location. Any transceiver gets hooked up to a spare receiver position, since it has its own TR relay built in. This is one of the best things I ever did for the shack, no ugly coax switches all over the place, no confusion as to what is hooked up, no dow key relays, etc. Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Mike Duke, K5XU > Sent: Sunday, March 26, 2006 8:18 AM > To: Discussion of AM Radio > Subject: [AMRadio] Switching between multiple rigs > > I want to be able to select between my current 3 rigs via a > switch. Since > rice boxes are included, I want the best isolation possible for the > unselected equipment. > > Recommendations, please. > > > > 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 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
Mark, There are a bunch of circuits at the following link. Check these out. I built several of these as a kid, (6V6, and 6L6 amps) using Acrosound transformers. They worked great, and have modulator possibilities for AM. At the age of 22 I loaned out my amplifier 40+40 watts / channel amp to my room mates brother. Something happened to it, and the guy trashed it into the dumpster. I am still mad about that 27 years later Jim http://www.the-planet.org/pdf/acrosound.pdf -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 3/24/2006
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 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 >
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 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.ne
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
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 >
RE: [AMRadio] Switching between multiple rigs
Here is what I did: I found a small rack mount box from work, and put lots of coax connectors on it, a bunch of terminal strips (screw type), and inside I have a bunch of rotary switches of various types. Its about 5 inches high, rack mount, front is painted black and the switches are labeled. I have from left to right, mod monitor sample control (high voltage variable capacitor, about 50 pf) Receiver selector switch, 7 positions, AC switch, 7 positions, this connects to various transmitters, Antenna switch, 4 position (big heavy duty ceramic switch) Transmitter antenna selector switch, 4 position heavy duty ceramic. Inside is a big open contactor mounted on rubber isolators, that is my T/R relay. I can pick any antenna (or dummy load), any receiver, any transmitter, and which transmitter keys the T/R relay. I also have a pair of coax connectors to go to the watt meter and or tuner, no matter what selections are made. I also have two small relays to do muting and so on, about 6 normally open, common, and normally closed contacts out the back on screw terminals. For the audio, I use one setup, one mike into the berringer, the berringer goes to a dual output audio amp that drives 2 modulators at once. One side goes to my pair of 813's rig, the other goes to the push pull 812a transmitter. The 32v3 uses its own D104. Any and all receivers have audio line level outputs going to a rack mount Marantz audio amp, 5 inputs, line in and outs, bass, mid and treble controls, headphone jack, low and high filters, etc. into one nice 3 way speaker. I use an icom 756 pro to excite the transmitters, it has two antenna outputs and a separate receive input, so all I have to do is push a button there. its keyed by one of the relay contacts in my switch box. I don't remember what I did with the push to talk setup, I have a small DPDT switch on the mike base that runs to both big transmitters to key them. This all adds up to a mess of wires and cables, but allows me to hook up anything, and select it once its hooked up. I can switch between transmitters or receivers in 2 seconds, do A/B/C antenna switches, all from one location. Any transceiver gets hooked up to a spare receiver position, since it has its own TR relay built in. This is one of the best things I ever did for the shack, no ugly coax switches all over the place, no confusion as to what is hooked up, no dow key relays, etc. Brett N2DTS > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Mike Duke, K5XU > Sent: Sunday, March 26, 2006 8:18 AM > To: Discussion of AM Radio > Subject: [AMRadio] Switching between multiple rigs > > I want to be able to select between my current 3 rigs via a > switch. Since > rice boxes are included, I want the best isolation possible for the > unselected equipment. > > Recommendations, please. > > > > 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] Switching between multiple rigs
I use the alpha delta coax switches for the antenna connection between transcievers. these have built in lightning protection if you run a good ground to the switch and short the unused antenna connection to ground. I do not use this on the output of the linear amplifier, rather on the input so 2 different radios can share the amp. One radio is a TS 2000 Kenwood, the other a Ten Tec Orion. I have never had a problem and the switch has an off position which connects neither rig and grounds both antennas for additional lightning protection. - Original Message - From: "Mike Duke, K5XU" <[EMAIL PROTECTED]> To: "Discussion of AM Radio" Sent: Sunday, March 26, 2006 7:18 AM Subject: [AMRadio] Switching between multiple rigs I want to be able to select between my current 3 rigs via a switch. Since rice boxes are included, I want the best isolation possible for the unselected equipment. Recommendations, please. 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] 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
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
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] Modulator design needed
There certainly is a driver transformer in a stock apache,the audio driver is a 12BY7A not a 5763,the 5763 is in the osc,buffer circuit. dale/ka5who - Original Message - From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; "Discussion of AM Radio" ; "Discussion of AM Radio" Sent: Sunday, March 26, 2006 12:59 PM Subject: Re: [AMRadio] Modulator design needed > Mark, > > Take a look at a Heathkit Apache schematic, (TX-1), for ideas. > > There is NO driver transformer. The 5763 driver goes to the Mod transformer and the EL-34s feed it for audio. > > Bob - N0DGN > > -- Original message -- > From: "W1EOF" <[EMAIL PROTECTED]> > > > > I've been gifted a nice mod transformer so I can build a modulator for my > > Johnson 6N2. I don't have a driver transformer so I'm looking for a design > > which doesn't need one. I'm sure the schematics are out there, but I keep > > finding ones with the driver transformer. Same with all my old radio books > > that I've looked at so far. Can someone point me in the direction of a good > > design that is online, or one that you can share with me via email? Thanks! > > > __ > 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
The Apache does use a driver transformer. A triode connected 12BY7 is transformer coupled to the grids of the EL34's. For AB1 operation, look at any of the hi-fi type tubes (EL34, KT88, 6550, 8417, etc). Most will deliver plenty of power without grid current. Another good choice is the 6146. 807's don't do very well in AB1. They just can't deliver the power of many other tubes. 73, Darrell, WA5VGO
RE: [AMRadio] Modulator design needed
I am planning on using a pair of 807s and that was what the xfmr was picked for. Both the power supply and modulator will be built with tubes, no solid state in this project. Not that I have anything against solid state... some of my best friends use solid state components. :-) So I should just look at some of the tube audio sites and find a suitable phase inverter circuit? I don't mind.. I was being lazy and hoping to just find a proven design/schematic that I could copy. I have some time too as I'm going to build the power supply first and get the 6N2 restored and running on CW. Then I'll tackle the modulator. 73, Mark W1EOF > -Original Message- > From: Mike Dorworth, K4XM [mailto:[EMAIL PROTECTED] > Sent: Sunday, March 26, 2006 2:37 PM > To: Discussion of AM Radio > Subject: Re: [AMRadio] Modulator design needed > > > > 807 in class AB1 at 400 volts 36 watts, 500 volts 46 watts, 600 volts 56 > watts and 750 volts 72 watts. > Usually subtract 10 to 15 percent for transformer losses etc. > Almost a perfect match for the 6N2 at any voltage used.. Mike
Re: [AMRadio] Modulator design needed
807 in class AB1 at 400 volts 36 watts, 500 volts 46 watts, 600 volts 56 watts and 750 volts 72 watts. Usually subtract 10 to 15 percent for transformer losses etc. Almost a perfect match for the 6N2 at any voltage used.. Mike > Just remember if you are going to use a tube phase inverter rather than a > driver transformer the modulator tubes need to be run in AB1 and not AB2. > You can't run any grid current without a driver transformer. > This leaves out 807's as modulators as you can't get very much power out of > them in AB1 but they are fine in AB2 as they are used in most rigs. Dx100 > etc. > > 73 > Gary K4FMX
RE: [AMRadio] Modulator design needed
Just remember if you are going to use a tube phase inverter rather than a driver transformer the modulator tubes need to be run in AB1 and not AB2. You can't run any grid current without a driver transformer. This leaves out 807's as modulators as you can't get very much power out of them in AB1 but they are fine in AB2 as they are used in most rigs. Dx100 etc. 73 Gary K4FMX > -Original Message- > From: [EMAIL PROTECTED] [mailto:amradio- > [EMAIL PROTECTED] On Behalf Of Peter Markavage > Sent: Sunday, March 26, 2006 1:34 PM > To: amradio@mailman.qth.net > Subject: Re: [AMRadio] Modulator design needed > > 12BY7 drives the driver transformer which, in turn drives the EL-34's. > > Build a phase inverter, like many of the Hi-Fi amps that don't use a > driver transformer to drive the EL-34's. > > Pete, wa2cwa > > On Sun, 26 Mar 2006 13:19:06 -0500 "Mike Sawyer" <[EMAIL PROTECTED]> > writes: > > Bob, > > I suggest you look at the schematics again. The output of the > > 5763 goes > > no where near the modulator. I don't have the schematics in front > > of me but > > I have done some extensive work in the audio section. > > Mod-U-Lator, > > Mike(y) > > W3SLK > > - Original Message - > > From: <[EMAIL PROTECTED]> > > To: <[EMAIL PROTECTED]>; "Discussion of AM Radio" > > ; > > "Discussion of AM Radio" > > Sent: Sunday, March 26, 2006 12:59 PM > > Subject: Re: [AMRadio] Modulator design needed > > > > > > Mark, > > > > Take a look at a Heathkit Apache schematic, (TX-1), for ideas. > > > > There is NO driver transformer. The 5763 driver goes to the Mod > > transformer > > and the EL-34s feed it for audio. > > > > Bob - N0DGN > > > > -- Original message -- > > From: "W1EOF" <[EMAIL PROTECTED]> > > > > > > I've been gifted a nice mod transformer so I can build a modulator > > for my > > > Johnson 6N2. I don't have a driver transformer so I'm looking for > > a design > > > which doesn't need one. I'm sure the schematics are out there, but > > I keep > > > finding ones with the driver transformer. Same with all my old > > radio books > > > that I've looked at so far. Can someone point me in the direction > > of a > > > good > > > design that is online, or one that you can share with me via > > email? > > > Thanks! > __ > 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
W1EOF wrote: I've been gifted a nice mod transformer so I can build a modulator for my Johnson 6N2. I don't have a driver transformer so I'm looking for a design which doesn't need one. I'm sure the schematics are out there, but I keep finding ones with the driver transformer. Same with all my old radio books that I've looked at so far. Can someone point me in the direction of a good design that is online, or one that you can share with me via email? Thanks! http://www.qsl.net/wa5bxo/driver1.html Granted, the devices are a bit large for driving something with smaller requirements, like whatever modulator tubes are in a Johnson 6N2, but you can reduce the solid state device to something that still has high-gain, but doesn't require as much Vcc. Perhaps an ECG198? John/WA5BXO (the guy who designed this circuit) uses it/has used the circuit with ECG198's in it to drive his push-pull paralle 813 modulator. I use this design with the ECG164's to drive the grids of my 250TH modulator. The 250TH's will take upwards of 500v pk-pk. I think the 813's only require *maybe* 100? 807's, I believe, are in the same range. Perhaps 811's could be driven with the smaller devices, as well. In case anyone is wondering: I don't want to mod my Johnson Viking to drive the 6N2 so I'm building a separate power supply and modulator for it. The power supply will server several radios (I also have a Johnson Viking Mobile I'd like to fire-up) and I may want to use the modulator on a different rig sometime. Considering that this is for a 6M/2M AM rig, all the more reason to go this way. So that's why I'm going this route of "separates." I can't think of a better application, than the solid-state audio driver for your needs. For that matter, the modulator, powersupply and driver circuit could all be built on the same chassis, with the same microphone plugged into it. Where you might have problems, is figuring out what modulation transformer to use. Different finals, are going to present a differet load to the modulator. Something (more) to think about. -- 73 = Best Regards, -Geoff/W5OMR A: Yes. > Q: Are you sure? >> A: Because it reverses the logical flow of conversation. >>> Q: Why is top posting annoying in email?
Re: [AMRadio] Modulator design needed
12BY7 drives the driver transformer which, in turn drives the EL-34's. Build a phase inverter, like many of the Hi-Fi amps that don't use a driver transformer to drive the EL-34's. Pete, wa2cwa On Sun, 26 Mar 2006 13:19:06 -0500 "Mike Sawyer" <[EMAIL PROTECTED]> writes: > Bob, > I suggest you look at the schematics again. The output of the > 5763 goes > no where near the modulator. I don't have the schematics in front > of me but > I have done some extensive work in the audio section. > Mod-U-Lator, > Mike(y) > W3SLK > - Original Message - > From: <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]>; "Discussion of AM Radio" > ; > "Discussion of AM Radio" > Sent: Sunday, March 26, 2006 12:59 PM > Subject: Re: [AMRadio] Modulator design needed > > > Mark, > > Take a look at a Heathkit Apache schematic, (TX-1), for ideas. > > There is NO driver transformer. The 5763 driver goes to the Mod > transformer > and the EL-34s feed it for audio. > > Bob - N0DGN > > -- Original message -- > From: "W1EOF" <[EMAIL PROTECTED]> > > > > I've been gifted a nice mod transformer so I can build a modulator > for my > > Johnson 6N2. I don't have a driver transformer so I'm looking for > a design > > which doesn't need one. I'm sure the schematics are out there, but > I keep > > finding ones with the driver transformer. Same with all my old > radio books > > that I've looked at so far. Can someone point me in the direction > of a > > good > > design that is online, or one that you can share with me via > email? > > Thanks!
Re: [AMRadio] Modulator design needed
Bob, I suggest you look at the schematics again. The output of the 5763 goes no where near the modulator. I don't have the schematics in front of me but I have done some extensive work in the audio section. Mod-U-Lator, Mike(y) W3SLK - Original Message - From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]>; "Discussion of AM Radio" ; "Discussion of AM Radio" Sent: Sunday, March 26, 2006 12:59 PM Subject: Re: [AMRadio] Modulator design needed Mark, Take a look at a Heathkit Apache schematic, (TX-1), for ideas. There is NO driver transformer. The 5763 driver goes to the Mod transformer and the EL-34s feed it for audio. Bob - N0DGN -- Original message -- From: "W1EOF" <[EMAIL PROTECTED]> > > I've been gifted a nice mod transformer so I can build a modulator for my > Johnson 6N2. I don't have a driver transformer so I'm looking for a design > which doesn't need one. I'm sure the schematics are out there, but I keep > finding ones with the driver transformer. Same with all my old radio books > that I've looked at so far. Can someone point me in the direction of a > good > design that is online, or one that you can share with me via email? > Thanks! > __ 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
Mark, Take a look at a Heathkit Apache schematic, (TX-1), for ideas. There is NO driver transformer. The 5763 driver goes to the Mod transformer and the EL-34s feed it for audio. Bob - N0DGN -- Original message -- From: "W1EOF" <[EMAIL PROTECTED]> > > I've been gifted a nice mod transformer so I can build a modulator for my > Johnson 6N2. I don't have a driver transformer so I'm looking for a design > which doesn't need one. I'm sure the schematics are out there, but I keep > finding ones with the driver transformer. Same with all my old radio books > that I've looked at so far. Can someone point me in the direction of a good > design that is online, or one that you can share with me via email? Thanks! >
[AMRadio] Modulator design needed
I've been gifted a nice mod transformer so I can build a modulator for my Johnson 6N2. I don't have a driver transformer so I'm looking for a design which doesn't need one. I'm sure the schematics are out there, but I keep finding ones with the driver transformer. Same with all my old radio books that I've looked at so far. Can someone point me in the direction of a good design that is online, or one that you can share with me via email? Thanks! In case anyone is wondering: I don't want to mod my Johnson Viking to drive the 6N2 so I'm building a separate power supply and modulator for it. The power supply will server several radios (I also have a Johnson Viking Mobile I'd like to fire-up) and I may want to use the modulator on a different rig sometime. Considering that this is for a 6M/2M AM rig, all the more reason to go this way. So that's why I'm going this route of "separates." 73, Mark W1EOF -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 3/24/06
RE: [AMRadio] Switching between multiple rigs
Mike Duke, K5XU says: I want to be able to select between my current 3 rigs via a switch. Since rice boxes are included, I want the best isolation possible for the unselected equipment. Recommendations, please. Mike Duke, K5XU -- Mike, This is a nice idea, and it would be helpful in many ham shacks. I wonder how far you want to go here. Some of us use the same microphone, compressor, equalizer, speaker, etc. on all our rigs. So what do you want switched? Here are some examples that come to mind: 1.) coax to tuner or antenna. A 3 position coax switch will do nicely here, and most will short out the unused inputs 2.) Microphone and speech processing equipment. This usually will need to be home-made, with attention to shielding, and the impedances involved. Ground loops might make this troublesome unless great care is followed, or go to a balanced line situation like broadcasters do. 3.) Speaker / headphones. A 2 pole triple position rotary switch with some means to provide a load (maybe 8 ohms) to the unused output is needed here. I say 2 pole switch because tying all the audio returns together might cause a ground loop and aggrivate your transmit audio. Regards, Jim WD5JKO -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/292 - Release Date: 3/24/2006
[AMRadio] Switching between multiple rigs
I want to be able to select between my current 3 rigs via a switch. Since rice boxes are included, I want the best isolation possible for the unselected equipment. Recommendations, please. Mike Duke, K5XU American Council of Blind Radio Amateurs
