[Collins] 516F-2 Lowering Voltages
Dr. Gerald N. Johnson
geraldj at weather.net
Wed Jan 25 16:09:45 EST 2012
On 1/25/2012 11:32 AM, Byron Tatum wrote:
> Hello-
> Thanks to everyone for their advice regarding my desire to lower my 516F-2
> voltages. After studying the aspects of using filament transformers as
> autotransformes to lower the supply voltages my final questions are:
> 1. What is preferred - To use the fil windings of 516F-2 itself as
> autotransformer function or to use a separate fil transformer in front
> of 516F-2?
Its hard to say. The external transformer takes more heat out of the
516F-2 transformer by not having any power losses in the 5 volt
windings. But it takes up space at the power supply location. Though I
know an electrician that used a bucking transformer for his whole house
to make lamps last longer. Either takes heat out by backing off on
saturation of the core that causes high peak primary currents.
> 2. If I use a separate fil transf in front of 516F-2 what should be its
> ratings?
The 516F-2 has a 4 amp line fuse. Conservatively, then the transformer
should be rated for 4 amps, though 3 will probably do and survive.
Probably 12 volts secondary at 4 amps, or 50 VA for a buck/boost
transformer with 120/240 primary and 12/24 volt secondary. There are
several on epay this week with that 50 VA rating. They have enclosed
wiring boxes to make inserting them in a bit of extension cord between
the wall outlet and the rigs easier to make neat than an open filament
transformer which is not commonly made these days, though Hammond and
most ham fests will have them. In the latest Mouser catalog Hammond
filament or low voltage transformers have prices similar to the
buck/boost transformers on epay.
> Thank you, Byron WA5THJ
> ______________________________________________________________
>
73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association
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