[Collins] KWM-2

[Glen Zook]

The only time that I have run into a "massive"
filament burnout on any of the S-Line equipment was
back in the mid 1970s.  A local Dallas area amateur
had gone down to Grenada to operate during a major DX
contest.  He broke off the alignment pin to the power
connector on one of his 32S-3 transmitters.  Frankly,
this is pretty easy to do and there are a lot of
S-Line equipment out there with broken alignment pins.

Somehow he got the power connector "off" and put 120
VAC on part of the heaters ("filaments"). 
Fortunately, the owner of the property from which he
was operating "owned" 50% of the yellow pages for that
part of the world and had a "deal" with the local
telephone company.  The local telephoned me and for
over 2 hours I "talked" him through what had to be
done to get the transmitter back working correctly.  I
am sure glad that I did not have to "foot" that
particular telephone call cost.

As for the problems with the sensitivity:  If the
alignment is pretty much "on" then you may have a bad
mechanical filter.  A quick test is to put a capacitor
(like 0.001 mfd) across the filter.  If the
sensitivity gets substantially better you have a bad
filter.

Also, tighten EVERY machine screw that goes through
the chassis and every nut.  All of the grounds in the
unit are made through these.  Over the years they work
loose and/or acquire corrosion.  Tightening them gets
all of the grounds back to where they should be. 
Also, there are usually several paper type capacitors
in the unit (how many depends on just when the unit
was made).  Replace these with orange drops.

If the ceramic trimmer capacitors are "frozen" (this
happens a lot with Collins equipment) then you are
going to have to disassemble them (remove the clip
from the underside of each) and remove the parts.  You
may have to take a razor blade (or a brand new #11
Xacto knife blade) and carefully loosen the very
fragile disk from the rotating portion.  Clean with
soap and water including the rubber diaphragm and dry
completely.  Reassemble and put the clip back in
place.  There are wires attached to the clips but you
do not have to remove these.

Make sure that there is a jumper between the two RCA
jacks marked for the noise blanker.  Also make sure
that the "dummy" plug is in place for the remote VFO.

Glen, K9STH

--- W4BYG <w4byg at swfla.rr.com> wrote:

Several had open filaments, one was shorted.  I've
never seen a radio with this many bad tubes, so I
suspect a previous owner did something wrong in
powering it.
 
After applying a siggen, I now have a very weak signal
going thru it, but the sensitivity is way down.


Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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