[TenTec] Omni 546-C SSB TX issue

[Marinus Loewensteijn]

I am looking for some input into solving a (potential) problem that I have with my Omni-C. 

history:
I obtained this transceiver some months ago and it had been sitting in a box for 28 years. Cosmetically immaculate but needed to have all the 100 nF bypass capacitors replaced since these were all cracked. I next had a few electrolytics go bad on me so replaced all the electrolytics. With that I made a boo-boo - I replaced the keying capacitor of 33 uF that was on the PC board with a value specified in the schematics of 4.7 uF. And then I build the TenTec keyer. When the rig was left on CW then when powering up it would transmit a dit before the whole rig ws powered up and this led to an early demise of the finals. I have replaced those with MRF 454 and all is FB working except for SSB TX.

I cannot find instructions for adjusting the TX mixer - what is in the circuit diagram in the manual uses a ring mixer in a IC package and what I have is a discrete diode ring mixer with two adjustable potentiometers.

Similarly the SSB exiter has an adjustable coil and I cannot find details on adjustment of that either.

My problem is that after the rebuild the audio is distorted. I wonder if this is due to some fault in the microphone or in the SSB exiter / TX mixer. CW works like a charm and output is fine too. Even when transmitting on CW the current nicely increases / decreases with the modulation, only it is garbled.

I do use this rig mainly on CW so it is not a problem but I do like to fix this part. Where do I start?

Thanks in advance for your help, Marinus, ZL2ML

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