New to me 142GTL Problems

[David Waits]

I just got A Cobra 142gtl from somebody that really needs a lot of work. first it has some sort of Variable AM output knob on the front that needs to be removed. It has a lazyman's Expo 'B' channel kit(Why, I don't know, it has an 8719 Chip), Then, there's the power output. Max AM deadkey is about 3 watts,swinging to 7. SSB is an abysmal 9 watts with the VR all the way up. This Radio has a 2SC2166 driver and a 2SC1969 final, it should be doing much better. I've tried adjusting the Driver and final Biasing to no avail, so, they're set back in their original positions

Any help here would be appreciated. As for experience, I was a HF Technician(30474) in the Air Force and held a tech plus ticket(KC8IBD) back in the 90s and worked on CBs. So, while I may have forgotten things, I'm not beginner.

 

[Robb]

Not a tech but have worked on many 142's. Setting the bias for driver and final with a mA meter is the essential first step. Do it as per the Service Manual specs. Next, peaking the TX coils is necessary to achieve peak output in USB mode. This is accomplished by using the CB Tricks Service Manual, a 50 ohm dummy load, a 1khz audio generator, and RF sampler, and a decent watt meter.