[GreenKeys] What is it?

[Harold Hallikainen]

On Thu, June 8, 2023 8:43 pm, Jeffrey Golas wrote:
> Its a dynamotor...motor spins generator to convert low dc voltage into
> higher voltage. (Thats as far as I know). This is prob to run the plates
> in tube gear, high voltage at not-so-high currents.
>
> Jeff
_

I agree that it's a dynamotor to generate the plate voltage for a
transmitter. When I was a kid, my father had a marine radio manufactured
by KAAR. It operated in the 2 MHz marine band (I remember the Coast Guard
was 2.182 MHz). The transmitter was AM with a parallel pair of 807 tubes
in the final and a push pull pair in the modulator. When you'd key the
mic, you could hear the dynamotor in the bilge start up.

Speaking of similar stuff, KD7VRG recently showed me a schematic of a
vibrator power supply for a receiver. What was interesting about it was
there were two sets of contacts, one for the transformer primary, and the
other for the secondary. The secondary contacts did the rectification (or
commutation?). It is similar to using FETs in a synchronous rectifier
circuit in a switching power supply. Very clever!

Harold
https://w6iwi.org


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