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[Amps] SB-200 Problem

To: <amps@contesting.com>
Subject: [Amps] SB-200 Problem
From: millscl+@pitt.edu (Chuck Mills)
Date: Mon, 04 Mar 2002 19:24:56 -0500
Hi there.  I have a problem with an Heathkit SB-200 that I'd like to
throw at the list.  I did a cursory search of the archives and did not
find anything specific to my problem.

Background:

Heathkit SB-200 Built circa 1977.  Currently in need of a minor rebuild
for maximum life which I plan to undertake (Harbach power supply, new
antenna relay, replace some ancient caps, etc...).  Currently has new
572B's with < 5 hours operating time on them.

Symptom:

While transmitting a while back, I let the smoke out of a resistor that
is part of the RF choke on the anode clip (one of the 80 5w wirewound
guys with the coil wound around it).  Obtained new resistor and soldered
it in.

Proceeded to put amp back in service.  Upon hooking it up, found a clear
frequency and got ready to transmit.  As soon as the antenna relay
clicks shut, the plate and grid current peg and another resistor self
destructs.  This one is off of lug 2 of V2 to ground (right most tube
socket when looking at the back of it).

I'm thinking that it might be that the antenna relay is not very happy
with life right now.  I'm a bit of a novice here and wanted to get some
insight from the group.

Thanks in advance....

Chuck - W3YNI
millscl@pitt.edu




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