[Kenwood] Thoughts on TS-820S prognosis

[Dave Edwards]

On 1/1/2014 2:27 PM, Kenneth G. Gordon wrote:
> 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?

Yes, either CW ...or "tune" position....which uses the CW filter.  I 
also had the low or no drive in FSK....which also uses
the CW filter.
>   
>> 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.

I could be wrong, but I am also suspecting the filter. And, as today is 
the one day only each year that there
is a discount at INRAD....I think I'll grab one.


>
> Kenneth G. Gordon W7EKB
>
> "Courage is being scared to death but saddling up anyway."--- John
> Wayne
>
>