Re: {Collins} 516F2 Power Supply

I have to chuckle everytime the tube vs solid state rectifier comes up, and it seems to come up quite often. My manual for the 516F-2 (July 15, 1974) shows two schematics for the 516F-2: one with tubes and one with solid state rectifiers. Everything else on the schematic looks exactly the same. I still use tubes in mine, but if Collins engineers built a solid state version with no other changes, it ought to be pretty safe. Since the supplies are choke input filter, I would surmise that the choke automatically works as a "soft start." Unless you add 100 mfd more capacity, as in "modern" thinking, there should be no need for additional protection.

----- Original Message ----- From: "William Levy" <wglevy@xxxxxxxxx>
To: <collins@xxxxxxxxxxxxx>
Sent: Saturday, April 14, 2012 2:07 PM
Subject: {Collins} 516F2 Power Supply


I have owned 4 KWM2A's and Power Supplys since the mid 70's, all second
hand, some off the surplus pallets. I have used solid state in each of them
without a problem.

Interesting enough I sold the first M2 and F2 when I bought a new KWM380
and on the Ebay market about 10 years ago the same power supply came back
to me with the same diode replacements still there.

I have taken note that some feel that the inrush or the higher voltage
might hurt the radio but this particular transceiver did fight the Vietnam
War 10 years after it was first conceived, was a backup in all our US
Embassies around the world, was dropped from aircraft and generally abused
so I have never worried if the plate voltage was a bit high.

That said I had a tube failure in my last KWM2A a few years ago that took
out a few stages down the chain and blew some coils and caps and I had to
go to a parted out radio to pick out the cans I needed as well as a few of
the transformers.

So if one wants to be careful I think better time could be sent checking
tubes and perhaps changing them every few years and lastly I have changed
some habits.

In the 70's I would leave the radio on for weeks at a time. Now I turn it
on in the morning and turn it off at night. In a real sense we are all
running out of the parts that require parted chassis's to keep these things
running. So beware the old tubes and for my money dont' be so concerned
about the diode replacements in the 516F2. Collins approved those 40 years

Sincerely, Bill N2WL

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