{Collins} KWM-1 Feed through Capacitor Mod Completed



Greetings and Happy 4th to the list

I had my KWM-1 apart for some routine maintenance and figured I should go ahead and replace
the "soon to die at any moment" feed through capacitor by using a simple modification that has
been discussed here previously. I took the chance of using two 600 volt .02uf 715P series Sprague
Orange Drops wired in series. The small ceramic stand off insulator worked perfectly because the
hole in the sub chassis where the old cap was mounted gave sufficient room for the "male" portion
of the insulator to mate through with the "female" portion. Soldered the caps from the anode to ground.
So far, it works great. I noticed not a single problem after testing on air and leaving on for a considerable
amount of time. With 1200 volts rating and .01 capacity measured with my trusty Sencore tester, it measured out
to .012 which seems fine to me... the old cap also measured .012 which is also fine by me.
I would have very much rather used a ceramic type but I could not source one in my stashes of caps,
so I took a chance. I have 100's of the wrong values rated at 2KV but not .01uf.
Bill Carns handed out some very good info regarding the choices and types that are favorable for this
application. I took some Hi resolution photos of the installation to give readers an idea of how I managed
to mount the components should anyone desire to see them.
The beauty of this modification is that it can be done for less than 1 dollar, and about 1 hour of time...
the KWM-1 has a boatload of chassis screws! After 54 years of service, I think Sprague did a remarkable
job of designing and building the feed through capacitors. A real testament to American craftsmanship.
Then again, it's not surprising that Collins Radio chose certain makes and types of materials in which to 
construct these wonderful pieces of equipment.
For future reference, I plan to write an article outlining some techniques for cleaning the tune and load
inductors. This is a very tricky and concise procedure that must be adhered to! Cuz, They Ain't making this
stuff No Mo! I look forward to Sunday's net where the KWM-1 will finally be back on the air.
I simply could not find the guts to check in with non Collins gear., hence my absence.
73 and Happy 4th!
Billy N6YW
 		 	   		  



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