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Does it take that long before the carrier show up? Or is the carrier there RIGHT AWAY.....but the modulation shows up late? I think that the transmit side is "shut off" when in RCV.... so it could be a delay in a mixer or some element in the transmit chain starting up....BUT... you would see...

In fact... the negative makes sense when I think about it. The transistors are NPN. The emitter is grounded. The positive peaks of the incoming RF will be shunted to ground through the P-N junction. But the NEGATIVE peaks will still be there (THAT is the rectification is that you talked about...

sneaking in a 'post of thanks'.... @loosecannon @brandon7861 I have always had a bit of a weakness in the area of 'driver and final biasing'. I was fairly sure about how bias worked on SSB rigs...being that it is generally Class B... But Class C biasing on AM rigs... was a little bit of a...

for clarity... when you say 'no ohms'........ was it zero ohms (shorted)? or was it infinite/OL ohms (open) ????

Agreed. If the meter black lead is for sure on a good circuit "signal" ground.... then the cathode of D64 absolutely should pull down to near 0 v. If it doesn't something is wrong. Another handy number I would like to have is the collector voltage of TR26 when it is IN and the radio is in...

SSB..... another one of my "clarification checks"........ If I am understanding everything to this point.......... IF..... TR24 and TR25 are installed....... and in the board....... If you REMOVE TR26..... XMIT/PA audio is GOOD. If you PUT TR26 back in..... XMIT/PA audio goes missing...

Hey Brandon! I don't know if you are still up...... here is my thinking... double check me and see what you think.... As I look at the circuit around TR26 I see the base bias leg as the bottom 6.48 v node... through R131 (10K) then through D46 then over to the AMC pot VR12 (500 ohms). The...

This is getting interesting..... because you should be able to clip meter black to ground.... meter red to the anode of D64 ..... and see that voltage change from about .6 v (one diode drop) and go up as you rotate the pot..... When the pot is at the bottom the cathode is grounded which means...

Where exactly do you have the red probe as you are measuring?

Hi Xracer,I am not sure if it was off to begin with or not.... but he did just tell me that... with TR24 IN...... and TR25 OUT.... he STILL has audio. And when he put TR25 back in... he lost the audio again. That makes it sound like TR24 is doing it's job..... but that TR25 is TELLING it to...

Just passing this along..... It looks like you are already determining that TR25 is telling TR24 to clamp the mic off. You can pull either transistor OUT and you recover your XMT/PA audio! So now we are "backing up a step" Either the components AROUND TR25 are honked.... CAUSING it to tell...

Sounds like you are on the way! I hate to see you have to use those parts.... but it sounds like something is hosed in the AMC/ALC that is "causing" it to think that modulation needs to be cut completely off. At least NOW you know what is doing it!!!!!!! I'll go back and take a look at the...

I would be really curious to know what you are getting on the collector & base of TR24... DC measurement. If that collector looks like it is a hard ground.... I would consider popping TR24 off of the board briefly.... and see if your mic functions suddenly start working. That collector...

WE ARE GETTING CLOSE I just backed up and reread your last update.... R126 Look on those schematic segments I sent!!! The output of R126 is tied to the AMC circuit.... TR24. And you said you had audio IN to R126 but NO AUDIO out of it. Check voltages on TR24 because it sounds like it is...

SSB.... see if any of this nonsense makes sense! :) Sorry it is rotated that is just the way the scanner picked them up.

I have a "gift" for oversimplifying things. That said, I am going to dig around a bit in the schematic but here is my thinking..... (and I am more or less just thinking out loud to try to organize my thoughts!) Below is a subsection of the block diagram. If RCV works in any mode.... then I...

not AT ALL to irritate..... simply to clarify....... when you say "No modulation on AM, SSB or PA" what I am interpreting is.... when the radio is set up and unkeyed, it will output sound for either AM or SSB ( I am assuming both USB & LSB) but when you transmit.... AM, USB or LSB.... no...

Interesting thought Mike. It would be good to have something like this in my stash for those REAL close up needs... like mine!!!!! Thanks.