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I almost did the same thing, until I looked at the posts date.

I got all exited when I saw the extra output. I'm going to play with it another day, it's a really cool little radio. We're going to see if a mosfet is better tolerated in there.

Thanks for the response, I should have known beter. I played with it for a while, it cleans up under 5w deadkey with under 20pep. But... After adjusting it back to max again the 2312 went into a no return meltdown along with D10 until I pulled the plug. It held on as long as it could. Thats...

Check this out, I've seen this before on another old am radio, but an alignment of the band pass area straightened it out. Is anyone familiar with this, what could be causing it? It was worse, shaped like 2 halves of two different measurements put together. This was a scrap/parts radio that I...

I understand the rules, and wish to enter the contest.

Nothing in the radios Mod meter, only in my external monitor meter. Thanks for the responses. I needed to hear that someone else has the same result. I think we're hearing what the modulator (AN612) rejects.

I've added talk back to a Grant classic (almost identical inside to the Grant DX), using the modulation meter switch to bypass the diode in front of the audio chip. I use a small amount of reverb sometimes and thought it would be cool to monitor at the radio. In SSB it sounds terrible (with or...

Ya, I noticed the missing LED a while back... Haven't noticed the other issues yet. Thanks for the heads up!

Audio chip is the 10 pin next to the regulator on the same sidewall. We want to check VCO voltage before we continue. Find Test point 9 it should be it should be somewhere to the left of center towards the front half, to the left of L21. Put the radio on channel 40 AM Hook your meter to the...

If pin 3 of the *audio chip* has 1 or more volts on it, it's a telltale that the PLL loop is not locked. It also mutes outgoing audio, including the PA (pulling C232 is a hack that keeps the audio unmuted by disabling pin 3, even between channels). It's probably due to the pin voltages at the...

If pin 3 of the *audio chip* has 1 or more volts on it, it's a telltale that the PLL loop is not locked. It also mutes outgoing audio, including the PA (pulling C232 is a hack that keeps the audio unmuted by disabling pin 3, even between channels). It's probably due to the pin voltages at the...

There was a TSB on this board that added a Zener diode in that spot as a safety limiter. That one looks pretty darn corroded to me, It should operate just fine without it. I would unsolder that wire and the diode and try to clean that area up with a little wire brush. Then see if the 8 volts...

Modification #18 in the PDF from post #43.

8 should be 8v during TX (6 and 8 should toggle, RX/TX). Pin 1 is being dragged down, it should always have 8v on it. Here is a schematic from CB tricks.org. It's for a 148, the regulator circuit is nearly identical. I chose it because it's very clear and searchable. The 1st thing I would try is...

Was going to do the controlled carrier mod after finding a failing VR8. I thought the 1K dimmer pot would be a cool spot for an adjustable carrier to use with "low drive" amps. Also noticed that the schematic drawing doesn't match the trace illustration, C102 would (still) be on the emitter the...

I have a hunch that the regulator is being bogged down by one of the grey 10v caps on the board. You've already checked the usual suspects, but even if they test "good" a recap can make everything run way smoother in the end. I use nothing less than 25v caps everywhere. See if pin 1 and pin 3 of...