FWD: RE: [Collins] Need KWM2 help

[Gerald Johnson]

---------- Original Message ----------------------------------
From: "Gerald Johnson" <geraldj@mail.isunet.net>
Reply-To: <geraldj@mail.isunet.net>
Date:  Wed, 26 Nov 2003 08:49:29 -0600

Open electrolytic you didn't test. That would be my first test. The one bypassing the receiver low voltage. When its open or has a high series resistance it lets feed back go through the whole radio, and electrolytics tend to fail with old age that way.

73, Jerry, K0CQ, Technical Advisor to the CRA

---------- Original Message ----------------------------------
From: "John Page" <k4kwm@hotmail.com>
Date:  Wed, 26 Nov 2003 04:15:27 +0000

>I have aKWM2 that is giving me fits. It hasnt beat me yet but its winning so 
>far. So read the following and if anyone can suggest anything, I sure would 
>appreciate it.
>
>Turned it on the other day and everything seemed normal. Transmit and 
>receive worked fine. Then I turned up the gain and "wow" feedback like mad. 
>Loud squeal. Starts at about 1/3 gain. Here is what I have done so far.
>
>* Swapped out V15 and V16 with known good tubes. no help
>* Opened the audio line at the gain control. problem gone
>* So I fed an audio signal in at the gain control and audio section worked 
>normal.
>* Reconnect gain and problem back.
>* Opened line from T5 to V15 (avc rec). Problem still there.
>* So I now think the problem is in the avc rect and prod det circuit.
>* Remove the coupling cap from V15A to V15B and problem still there.
>* Ok so maybe its in the prod det.
>* All voltages and res. measurements ok.
>* Replaced all caps in the prod det circuit and checked all res. problem 
>still there
>
>So if anyone can shed some light maybe I can still whip this guy. Thanks in 
>advance. John
>
>
>
>John Page K4KWM
>Hollow State since 1953
>(ex W8PKU,N8BLB,NA8O)
>
>_________________________________________________________________
>Is there a gadget-lover on your gift list?  MSN Shopping has lined up some 
>good bets!  http://shopping.msn.com
>
>