[Boatanchors] Help need for my Drake 2-C

[Kurt Brandstetter]

Hello from Vienna !

Today I got a wonderful clean Drake 2-C (from USA); I've never seen such a
clean chassis before. The only dirt you can see on the copper are the
fingerprints if you tough it. BUT, I have some problems with the AVC.

First some facts:

The receiver works 100 % ok on all bands when the AVC is switched off. If I
turn the AVC on to fast or slow, the S-meter shows without a connection to
the antenna about 5/9+20 (also on all bands and modes.

The voltage on testpoint 1 (TP1) with the AVC off is - 1.35 V; if I switch
AVC on it goes up to - 5.5 V when the RF gain is turned full to 100%. If I
turn the RF gain back to zero, the voltage is about - 13.5 V. This -5.5 AGC
voltage blocks the receiver so hard, that I can only receive (very quite)
some strong AM broadcast stations on 40 meters (they are on an other
receiver 5/9+40).

I have tried to check the receiver sensivity variable resistor but cannot
correct the high AGC voltage. 

The voltage on the IF tube are correct also the resistances measured as
described in the manual. 

So I think, the failure must be in the AVC circuit (the small print board).
But before I have to beginn to check all from the front to the end of the
receiver, I want to ask you. Where shall I look first ? Am I right that the
AVC voltage is produced by the diode (D9) connected to the grid 1 of the IF
tube or is it produced by the AGC amplifier which is connected via a 220 pF
condensor to the plate of the IF tube ? 

Where shall I begin to look for the failure ?

The bad thing is, that I have learned how to check and repair tube
receivers, but exactly this AVC circuit is solid state :-(( . And thats a
thing I don't really understand. 

Thanks for your help in advance ! I'm sure someone of you knows the 2-C
quite well.
-- 
73 de Kurt OE 1002419          ICQ-UIN 43074273
CCA member AC01-01249 NCDXF #4175  INDEXA #1720 
Homepage: http://www.swl.net/oe1002419   
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