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[W1JPP]

I have no issues getting xmit full power out on all bands...

but occasionally, out of the blue, it will stop receiving - as if I'm connected to a dummy load.

I have other radios, a/b switches etc and I've ruled out an antenna or coax issue...and sometimes when I tune up on a new band, or the same band, going back to peak the ALC with drive, the sound /signals will come back...but I cant replicate the problem or solution.

I'll probably end up having an expert go thru it, but I thought I check here first in case there are any known issues or first places to look.

Thank you.

[K1KIM]

Loose solder connection on the VFO or Oscillator board??

I'd like to hear other's opinions.

[W1JPP]

I reached out to someone who has this radio - he said if I rock the send (xmit) back and forth and the sound / rx comes back its usually the TR relay... (transmit relay)...

from the service manual, Looks like that part number is RL - #S51-4031-05

sure enough, if I do that, rock the send/xmit switch the sound comes back...

I know this relay just pulls out, from the bottom (removing bottom cover)....just not sure if I can find a replacement relay..

This is the relay I saw...I pulled it just to see if there was anything obvious...but nothing visual...

https://www.youtube.com/watch?v=pU4pI5DQ3IQ

[AJ8MH]

Check connections closely and carefully.  I've had intermittent receive with bad relays, bad coax connectors (male and female), corroded connections on balans and loose screws inside antenna traps on a beam.  Each and every one could be temporarily fixed by running a little transmit energy through the path.

[N8CBX]

rock the send/xmit switch the sound comes back...

It could be the antenna relay (there is a second relay almost identical), but turn on the marker signal osc. and see if you can hear it. The marker is wired in after the relay.
There are no NOS factory relays available.
If you are getting full power out (and ALC with power), it cannot be the VFO, CAR and HET oscilators.
Jan N8CBX

[W1JPP]

It was the transmit relay. I opened it up and upon close inspection there is small plastic piece on top of the relay that basically pulls back the contacts in the relay when you transmit.

That piece had one leg broken. So with the other leg connected sometimes it would work fine and other times not. I tried a temp repair with jb weld and it worked for a bit, but the plastic piece broke in another spot. It was very brittle

It looks like at some point the company changed design and now it’s a much stronger linkage between the arms that pull back and the piece that pulls the contacts back.

Interestingly when I was only partially working I tried swapping with the antenna relay. So then my transmit was fine but signals that were s9 dropped to s6. I had an a/b switch, same antenna and a fully functioning ts-520s
 
I know the two relays have different ohm ratings

I’ll put a working relay in and I’m sure it will be fine.

Thanks all.