[Kenwood] Thoughts on TS-820S prognosis

Wed Jan 1 14:27:46 EST 2014

On 1 Jan 2014 at 14:09, Dave Edwards wrote:
> After it sat on a shelf for too long, I plugged it in recently.
> During tune up, I found very low drive on the ALC meter....with
> carrier control full cw.

You mean, in CW?

> Tried a new driver tube, no change.
>> Then, I noticed USB and LSB are fine...with plenty of drive.
>> I also noticed that in CW....(which defaults to using the CW filter) I
> noticed signals were about 3 'S' units low, and signals on CW sound
> "pinched".

That sounds to me as though the CW "BFO" crystal has drifted off 
frequency, and is no longer within the filter passband.
> There is an internal jumper which enables the CW filter. I set it to
> not use the filter. Now, everything works fine...plenty of drive, CW
> sounds great (but with the SSB bandpass).

Doing this would "mask" whether or not the CW BFO crystal had changed 
frequency. It would sound perfectly acceptable in the SSB filter, but still be 
way off in the CW filter, far enough to be outside the passband instead just 
inside one edge of the filter.

> So, I'm thinking the filter went bad....Isn't that the most likely
> culprit!!

Well....maybe....as I said, I'd be looking at the BFO crystal frequency first. 
It's easier and less expensive.
In my case, I did have a 400 Hz. crystal filter "go bad on me" in a Heathkit 
HW-101 which exhibited about the same symptoms as your rig.
I had to replace the filter.
Kenneth G. Gordon W7EKB
"Courage is being scared to death but saddling up anyway."--- John 
Wayne