Electronics > RF, Microwave, Ham Radio

#63 A look at a mint Collins KWM 2A in for repair

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Radio Tech:
I had the opportunity to work on a Collins KWM-2A this week end. Did not have4 time to do the repair on camera due to getting the radio back to the owner.  Rig came in with a broken power port. While testing the unit I found several bad solder joints and repaired those as well. 


#63 A look at a mint Collins KWM 2A in for repair
In this video we look at a viewers Collins KWM-2A. I have to install a new power port and repair a few solder joints then align the radio off camera.




German_EE:
Given their age the cosmetic appearance of Collins gear always amazes me. There was some for sale at Friedrichshafen and it looked like it was fresh from the factory.

When owners kick up a fuss about fitting the wrong replacement part in their radios you sometimes have the option of fitting the new part INSIDE the old one. I've sometimes done this with can capacitors where the new part has a higher voltage rating and yet is half the size.

AF6LJ:
Good Video.
Never worked on one of those...
I'd love to have a KWM-1...
I have worked on a 75-A4, and used one for a few weeks back decades ago.
A friend, and member of our 75 meter rag chew group has a 75-A4 that he replaced all the mica caps along with all the electrolydics and black beauties. He recently had one of the ceramic disc caps fail, but it is a sixty year old receiver that gets use on a weekly basis.

Radio Tech:

--- Quote from: German_EE on July 25, 2016, 03:57:54 pm ---Given their age the cosmetic appearance of Collins gear always amazes me. There was some for sale at Friedrichshafen and it looked like it was fresh from the factory.

When owners kick up a fuss about fitting the wrong replacement part in their radios you sometimes have the option of fitting the new part INSIDE the old one. I've sometimes done this with can capacitors where the new part has a higher voltage rating and yet is half the size.

--- End quote ---

It is amazing how well they hold up after so many years. Amazing what the price of these radios are also. :scared:
Yep, Have stuff a many caps over the years. Specially guitar amps.

Radio Tech:

--- Quote from: AF6LJ on July 26, 2016, 01:06:25 pm ---Good Video.
Never worked on one of those...
I'd love to have a KWM-1...
I have worked on a 75-A4, and used one for a few weeks back decades ago.
A friend, and member of our 75 meter rag chew group has a 75-A4 that he replaced all the mica caps along with all the electrolydics and black beauties. He recently had one of the ceramic disc caps fail, but it is a sixty year old receiver that gets use on a weekly basis.

--- End quote ---

Thanks Sue.
The -2A was not too bad. Just time consuming. But he is very happy with it. Worked on many of them.
Now the KWM-1 is a different story. He bought it non working. receives very well.  But no output. At the moment I am missing the 260 VDC. These are a pain to work on. All wiring is in a loom and no underside illustration showing what each part is.  Using the SA it a "sniffer" on the end of a piece of coax I see I have drive signal on selected frequency. That is a good thing.
Part that gets me is someone did a recap job. Looks decent.  But in the back of my mind I have to wonder is this when the failure occurred. Before, during, or after.... :-//

I have never worked on a 75-4A. Maybe one day.  Seen caps in RF stage fail often. Specially in the FT-101.

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