[Collins] 30S-1

[Dr. Gerald N. Johnson]

On Wed, 2006-03-01 at 13:12 -0500, Phil LaMarche wrote:
> Just purchased a 30S-1 with new tube.  Burned it in for 3 hours.  Tuning it
> up, I get full power but the multimeter is all the way to the left and not
> at zero.  Also has a hum that I can hear in the amplifier and is on the
> signal.
>  
> Ideas, please.
>  
> Phil

Needs to be loaded heavier to move the multimeter up to zero. Right now
its running negative screen current from being loaded too lightly.

The hum is probably coming from dried out electrolytics in the screen
and bias supplies. They need to be replaced. In the process its a good
idea to increase the capacitance on the screen supply by about 350
microfarads to improve the transient RF power, makes for better punch on
CW.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer