I was having a nice quiet Saturday. So, why not recap this Cobra 146 GTL I happen to have lying around?
Recap seems to go well, everything facing the right way, etc, so let's fire it up!
Bad LED on channel readout, no RX or PA audio, weird transmit problem with nothing showing on meter, but trace on the scope.
LED problem fixed with reflow of the darned 90 degree connection they used in this radio. No audio took a bit longer, turned out to be one of the pins on the audio amp chip hadn't been correctly soldered when it was replaced. Which explains why it ended up on eBay as parts or repair. Resolder that pin, audio problem fixed.
This leaves the transmit power problem. No matter what I do, I can't get the meter to register that this thing is producing any kind of power. As a control test, I throw another radio on the bench that was working the last time I played with it. Meter doesn't register that, either. So I start undoing coax cables on the meter side and that's when I find it.
The little sample port box I use to break out signal for the scope and frequency counter had a loose connector that had spun and broken the conductor inside. Found a suitable chunk of wire and back in business.
Radio was fine, pumping out 4 watts dead key on AM and somewhere over 12 modulated on SSB.
The point? When you can't figure out what the problem is with the radio, maybe it's not the radio.
Recap seems to go well, everything facing the right way, etc, so let's fire it up!
Bad LED on channel readout, no RX or PA audio, weird transmit problem with nothing showing on meter, but trace on the scope.
LED problem fixed with reflow of the darned 90 degree connection they used in this radio. No audio took a bit longer, turned out to be one of the pins on the audio amp chip hadn't been correctly soldered when it was replaced. Which explains why it ended up on eBay as parts or repair. Resolder that pin, audio problem fixed.
This leaves the transmit power problem. No matter what I do, I can't get the meter to register that this thing is producing any kind of power. As a control test, I throw another radio on the bench that was working the last time I played with it. Meter doesn't register that, either. So I start undoing coax cables on the meter side and that's when I find it.
The little sample port box I use to break out signal for the scope and frequency counter had a loose connector that had spun and broken the conductor inside. Found a suitable chunk of wire and back in business.
Radio was fine, pumping out 4 watts dead key on AM and somewhere over 12 modulated on SSB.
The point? When you can't figure out what the problem is with the radio, maybe it's not the radio.
