UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Superstar 6900N V6

SiriusHardware · 23rd May 2020, 8:04 pm

That means that MIC MUTE is not asserted by the microprocessor which is a relief as it was difficult to imagine why it would be.

Instead it is the BP MUTE transistor which is enabled and this will not cut off the microphone audio as it is clearly intended to kill the TONE (roger beep? 'BP'?) output from the microprocessor.

So now we can say that it is the ALC MUTE transistor Q513 which is keeping the microphone audio muted in SSB mode, therefore yes please, go ahead as outlined in #71 and see if Q513 is still turned on in SSB TX with those alterations made.

Mike W, just working to restore SSB RF to the input of the transmitter at the moment. We will eventually get back to the transmitter. If you've read the thread through you will know that crackle has owned this from new and has not altered any factory set adjustments.

It is possible that with new output devices fitted there was a need to readjust the bias, but as we do not have the service procedure or manual, knowing what to set it to would be a bit of a guess. I prefer to leave things exactly as factory set / undisturbed until there is absolutely no alternative.

23rd May 2020, 8:04 pm	#76
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,560	Re: Superstar 6900N V6 - Fault with SSB mode That means that MIC MUTE is not asserted by the microprocessor which is a relief as it was difficult to imagine why it would be. Instead it is the BP MUTE transistor which is enabled and this will not cut off the microphone audio as it is clearly intended to kill the TONE (roger beep? 'BP'?) output from the microprocessor. So now we can say that it is the ALC MUTE transistor Q513 which is keeping the microphone audio muted in SSB mode, therefore yes please, go ahead as outlined in #71 and see if Q513 is still turned on in SSB TX with those alterations made. Mike W, just working to restore SSB RF to the input of the transmitter at the moment. We will eventually get back to the transmitter. If you've read the thread through you will know that crackle has owned this from new and has not altered any factory set adjustments. It is possible that with new output devices fitted there was a need to readjust the bias, but as we do not have the service procedure or manual, knowing what to set it to would be a bit of a guess. I prefer to leave things exactly as factory set / undisturbed until there is absolutely no alternative.