[Collins] Fw: No P.A. Plate Current on 32S-3

Mon, 4 Aug 2003 12:07:04 -0500

Check the 820 Ohm resistor on pin3 of the 6146's it may have gone up on ya,
very common problem...

Thanks & 73's Dutch
Please visit my Collins web site.
http://users2.ev1.net/~wb7dyw/

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Dr. Gerald N. Johnson, electrical engineer
Sent: Monday, August 04, 2003 8:48 AM
To: Peter Scheller
Cc: [email protected]
Subject: Re: [Collins] Fw: No P.A. Plate Current on 32S-3

There should be 40 to 50 ma idling current in the PA without drive. The
easiest way to not have idling current is to have too much bias, but
then the drive should raise the plate current. The next easiest failure
is to have no screen voltage. There are a pair of jacks on the back of
the chassis with an internal jumper that is cut to remove PA screen
voltage when the 32S is used with a transverter. Check that jumper,
probably by plugging in a RCA to RCA cable between them.

The PA tubes could be bad.

The idling current should be set by the bias adjustment pot on the power
supply to the manual's specifications. A little plate current will make
the tubes more sensitive to drive.

73, Jerry, K0CQ, Technical Advisor to the CRA

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