[Amps] Kenwood TL-922 soaring bias current in SSB Mode ?

[Tom W8JI]

> I have (again) a problem with a TL-922.
> In CW (lower HV) on any band in TX mode without any drive 
> power applied
> the grid current keeps steadily on the preset value by the 
> Zener Diode.
> While in SSB mode where the Zener is bypassed IG starts 
> soaring after a
> few seconds and it would not stop unitl TXing is 
> interrupted.
> Any hints what has to be done to cure this problem?

The grid current can soar for many reasons, including a bad 
tube or bad components from the grid pins to ground.

Is the 922 unmodified? If it was my amplifier I would ground 
the grids with very short leads right to the chassis at each 
grid pin.

Do the tubes show even anode color?

What you are saying is the grid current soars between words 
on SSB? The grid current should be very low when talking on 
SSB.

> Is this oscillation caused by the increased HV in SSB 
> mode?

How do you know it is an oscillation and not dc circuit 
problems?

73 Tom