[Johnson] Invader Problems

[John Lawson]

On Tue, 19 Sep 2006, David C. Hallam wrote:

> I am operating in the 200 watt position.  After the wait, I can tune to
> normal full output on my Bird 43 wattmeter. High and low voltages are OK.
> After hours output drops to 0.  Grid bias is normal and no power output on
> any band and no signal in the zero position unless I put a receiver antenna
> lead inside the cabinet.  With the any setting of the zero level control and
> antenna coax connected as normal, I can not hear a spotting signal.  With a
> general coverage receiver, I can hear the 9 MHz carrier oscillator and the 5
> MHz vfo and a little output from the 2nd mixer as stated above.


   What does the Plate Current do during all this?

   Can you read the Buffer current?

   If there is a 'no-drive clamper circuit', has it gone wonky?

   Certainly a lot of this does point to Driver circuit failure...


Cheers

John  KB6SCO
Valiant, Ranger, Elamc AF-67
R-390, R-390A, R-388