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Author Topic: Advice on powering up on old Collins  (Read 1633 times)
K4NFX
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« on: January 14, 2013, 06:42:46 AM »

I just picked up a Collins KWM-2 1960 model.  the radio has not been powered in 18 years.  it is in good condition cosmetically and had been well taken care of by the previous owner.  I am new to tube radios and don't want to damage it by just plugging it in.  Any advice on this would be greatly appreciated

K4NFX
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AC2EU
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« Reply #1 on: January 14, 2013, 06:55:49 AM »

First thing to do is physically inspect the chassis for any obvious problems. Then throw an ohm meter across the filter caps looking for shorts to make sure that they are not the reason that it was retired 18 years ago.  If it all seems OK, bring it up slowly on a variac so that the inrush current does not unduly stress the old  power supply. Once this is done, and no smoke escapes, the other functions can be tested.
It's probably a good idea to replace the filter caps anyway...
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K4NFX
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« Reply #2 on: January 14, 2013, 12:32:39 PM »

Thanks for your reply. The chassis is very clean everything looks good. It was retired because the ham that owned it went Sk and it was used for a short time by his daughter and her husband. They lost interest in ham radio and just turned it off. Now they are moving and are getting rid of things. I will get some help with a variac from one of our local hams.

Thanks again.

K4NFX
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KG6YV
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« Reply #3 on: January 14, 2013, 02:19:05 PM »

Definitely use a variac and I recommend replacing any electrolytic capacitors in the radio AND in the power supply.  Also, if the power supply is a 516F2 there is a selenium rectifier in there that should be replaced with regular diodes... Selenium puts out toxic gas if it shorts and melts.

Have fun, the KWM2 is still a very useable transceiver. 

Oh, check to see if it has sealed relays or open frame relays.  KWM2s built before 1964 had open frame telephone relays which will need a real good cleaning if they are used in yours.

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