Hi, when I key this transmitter up I am getting a 4 watt dead key but no modulation in AM but am getting modulation on SSB, I have seen it recently modulate on am as I was wiggling the 12ax7 tube but has stopped all together, I figured it was a loose and or dirty tube socket so I cleaned it and tighten up the socket as well as I could and now still have nothing even if I wiggle that tube, I tested the mode switch with continuity as well as I could and appears all wires were making contact, can anyone give me a few more hints on what to check as I am stumped at this point ! Thanks
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Browning Golden Eagle Mark III transmitter " no modulation " issue ?
- Thread starter Danzik
- Start date
I have a mk3 but am not familiar with the insides. Might be something in the ssb / AM selector switch? I am sure that someone who knows this radio will chime in.
Yeah, I know this switch can cause alot of issues, but at least the terminals that I can get to had continuity when they should
I believe it to be somthing else since I was wiggling that tube and it kicked it a couple times, I now however do not believe it to be the socket though
Loss of mike audio from a failed mode selector usually starts with a burned resistor R51.
The contacts are placed so close together on the insulating wafer that the insulation will break down and leak high voltage into low-voltage circuits causing mayhem.
And if your R51 has bright, shiny orange-orange-red color bands, it's not part of the problem.
It's the most common failure we see caused by the inevitable breakdown of the brown bakelite insulation on the mode selector. Might not be causing your fault. Worth a look.
73
The contacts are placed so close together on the insulating wafer that the insulation will break down and leak high voltage into low-voltage circuits causing mayhem.
And if your R51 has bright, shiny orange-orange-red color bands, it's not part of the problem.
It's the most common failure we see caused by the inevitable breakdown of the brown bakelite insulation on the mode selector. Might not be causing your fault. Worth a look.
73
Thank you very much for that comment I wondered how the mode switch actually broke down now I understand how by your comment, now I know even if there is continuity where there should be there can still be voltage leaking in that shouldn't be ! And I will also look at R51 closely and seeLoss of mike audio from a failed mode selector usually starts with a burned resistor R51.
The contacts are placed so close together on the insulating wafer that the insulation will break down and leak high voltage into low-voltage circuits causing mayhem.
And if your R51 has bright, shiny orange-orange-red color bands, it's not part of the problem.
It's the most common failure we see caused by the inevitable breakdown of the brown bakelite insulation on the mode selector. Might not be causing your fault. Worth a look.
73
I will look into this tube also ! I found it odd when I wiggled the other one a few different times the modulation kicked in though, odd as it did it several times but now, nothing
Also, if this resistor is ok in this unit I know that it is not in another one I have ! So I may be buying the ceramic fix from you soonLoss of mike audio from a failed mode selector usually starts with a burned resistor R51.
The contacts are placed so close together on the insulating wafer that the insulation will break down and leak high voltage into low-voltage circuits causing mayhem.
And if your R51 has bright, shiny orange-orange-red color bands, it's not part of the problem.
It's the most common failure we see caused by the inevitable breakdown of the brown bakelite insulation on the mode selector. Might not be causing your fault. Worth a look.
73
Scrubbing the pins of each tube, then blasting tube sockets with a pressurized can of cleaner like CRC "QD" solvent may reveal bits of tobacco smoke tar. Until all of it is flushed from a tube socket it will continue to cut in and out. We learned to flush each tube socket this way as each tube gets pulled out to put into the tube tester. And if the radio didn't belong to a chain smoker, that would reduce the work to get the tube sockets to function smoothly, even while the tube is rocked gently in the socket. Any noise this causes is an indication of a future intermittent fault at that socket. Tubes should not generate noise when wiggled lightly.
73
73
Yeah, I normally use a torch files and a small needle to try to tighten prongs a tad and Deoxit contact cleaner on the sockets
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