My Collins KWM-2 Restauration Project

S/N 10831

by Ernst F. Schroeder DJ7HS

I got my first Collins device, namely this KWM-2, not before early 1991. I bought it from Peter, DJ0JE. He had advertized it in German amateur magazine "cq-dl" and that had arrived shortly after Christmas 1990. There was no time to hesitate, I picked up the phone and the deal was struck. Then in early 1991 I took the car and the xyl and drove about 300 miles on the autobahn from Hannover to Kaiserslautern. I got the KWM-2 with PM-2, Peter got his compensation and we both were happy. And when I left, I spotted a 312B-5 sitting in a corner. Was it ...? No way, its directional coupler was in use for a different station. I had to retreat, but I kept this firmly in mind.

On the way back home I had plenty of time to explain and talk about amateur radio. Must have been quite a good story, as the xyl made up her mind to join the ranks, even with CW. Two years later she passed the exam and got her call sign.

Back at home I carefully unpacked the KWM-2 and PS-2 and put them on the work bench. This was definitely a time before I got to know the Electric Radio magazine, the Collins Collectors Association and as well the Collins Radio Association with their wealth of information and useful help. Also before I had a chance to learn all those special cleaning methods used by the "boatanchor" community.

So, I applied common sense and standard engineering and radio repair techniques. First I carefully cleaned and got the PM-2 to work. Then I gave the KWM-2 a try with all tubes removed. Smoke!

After some searching I found that the installed Waters rejecting tuning model 340A had several mechanical shorts, which had taken with them a choke in the filament circuits.

No question, the Waters had to move out and the choke was replaced. Then I started the cleaning process. First I dismantled everything that could be removed, and then I started a gentle cleaning process, not the brutal "water from a hose and let dry in the sun" that is sometimes advocated.

Yes, this is how my Collins KWM-2 looked like, after I had started with the restoration job.

my KWM-2, taken apart

Lots of brown stuff covered the characteristic grey, green and aluminum colors of the Collins S-line.

Here is another picture, seen from the back. Of course, the PA tubes are just there to show their position, not for cleaning them.

another view of the KWM-2

And this is how it looks now after all the work I put into it: clean and shining. A pleasure to look at, a real work of Art.

the KWM-2, now clean and shining

After I had the KWM-2 up and running, I spotted a 516F-2 power supply and even a 30L-1 power amplifier, which I added to the set-up. Even better, I was able to obtain a 302C-3 directional wattmeter with coupler. You guessed it? Yes, I was able to exchange this for the never forgotten 312B-5 in Kaiserslautern.


 

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This page is copyright © Ernst F. Schroeder, all rights reserved.
It was last updated on 18 February 2013 and has been made possible through QSL.NET by K3TKJ.
Thank you, Al!