[Heathkit] DX-100B on Phone - bad audio distortion / oscillation

[Rick Poole]

Received in private email:

 >>>>>
>   Disconnect the MIC and provide a good short across the connection.
<<<<<

I did disconnect the mic but didn't short the input... I'll try 
that.  In any case, the problem is now appearing in CW as well as phone.

 >>>>>
>My DX-100 oscillated (when I first got it, used) until I soldered 
>the shield between the driver and PA tubes to the chassis in 4 
>places on each side (all copper plated), you could remove it, clean 
>the chassis & the bottom of the shield and apply a coating of No-Ox 
>to mating surfaces.
<<<<<

The DX-100 had a copper (or copper-plated) chassis but the DX-100B 
went to a steel chassis.  I can't remember how well steel takes 
solder but I'll give that a shot.  I'm going to be loosening and 
retightening all of the hardware anyway so will try No-Ox in 
appropriate places.

Thanks...