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There's going to be some capacitors you're going to likely have to replace, as there will be several 10V and 16V caps that have failed from the over-voltage. Likely, those will all have to be pulled and replaced before sending it back to the owner.
~Cheers~
The 2970N2's aren't too awful, but honestly your best bet is to run a 2950 and an amp.
Any time you run a radio/PA combo you can potentially have heat issues. The heat generated by the PA board has nowhere to go but rise up into the main PCB and can cause drifting problems in the case of the...
That is EXACTLY the reason why I don't run on 38LSB... it's a cesspool on that frequency with all the echo, roger beeps, overmodulated radios, class C splatterbox amps and such. I run SSB 95% of the time, but you'll never find me on that frequency.
~Cheers~
While I personally won't run HF rigs on 11M, I don't have a problem with people running them there. I'd much rather have people run HF rigs on 11M any day of the week compared to those junk "export" radios. "Export" radios just make me cringe. But, it's about their personal preference, I...
I think one of the rarest radios I have owned was the old Cobra 29XLR Gold. I think those were handed out to distributors and shops that sold an "X" amount of units at the time. I think I still have it somewhere, if I can find it I'll post a pic.
~Cheers~
You shouldn't be getting that much voltage on the collectors of the driver and final... I'd suspect a bad AM pass regulator. Replace the C1419 with a TIP41C or similar. Should be getting 2-7V depending on the state of VR10 on the collectors in AM mode.
~Cheers~
In AM mode, check the voltage at the collector of the final, should be around 5V +/- 1V. If it's lower than that, I'd suspect a fault in the AM pass regulator circuit. Check that voltage and let us know how you get on. (y)
~Cheers~
LC is correct, and with that being said, pin 3 does have the correct voltage on it. Thank you for the correction, LC.
Check D58 and D11, they are located near VR3, the squelch pot. Make sure they have not gone short. Let us know how you get on.
~Cheers~
The voltage on pin 3 is incorrect, that's the VRef pin. That should read +8V. Replace C133 and C134 and see if that restores operation. Let us know how you get on.
Also, does unsoldering the wire going to pin 5 on the mic jack get it to drop out of TX?
~Cheers~
Buttfuzz:
You have to have anywhere from 3.65-4.2V (or roughly 1/2 VCC) to pin 10 to get the +192 state. That's why I made a circuit with a LM7805 and a 3.6V 1W zener diode, with a couple caps and a variable resistor, to dial in the 1/2 VCC necessary to get the +192 to work. I incorrectly...
Unfortunately, he lost the CPU on it, Shockwave. That 2970N2 is a goner unless he can replace the CPU. There is another way to directly key an amp like that. Just involves a small relay that can be mounted internally inside the radio and needs just a couple of wires and a 1/8 inch mono jack...
ButtFuzz:
This mod will make it go up another bank of 40, so it will increase, if you use the original 11.325 loop mixer crystal. That being said, you can cover 10M SSB voice if you go N+128.
~Cheers~
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