[ARC5] Dynamotor Voltage Reduction

[David Stinson]

Fair Radio sold a ton of these dynamotors.

https://photos.app.goo.gl/VK5Tvb74vaOGUiR12

Sold in both 27 and 14 Volt versions, they were
 originally designed for a Magnavox interphone
amp that serviced the TCS.  They fit on the back
of
Command Set receivers, but they output 285VDC;
much
too "hot" for this purpose

https://photos.app.goo.gl/vI5KZ3y961HsTbnr1

A simple way "calm it down" is to open the base
and insert a 5-watt Zener in the B+ lead,
cathode toward the dyno and anode to the output.
Cover it will heat-shrink tubing.  
A 1N5371 will take 285V down to 220V.
A 1N5378 will drop it 100V, but that might
be pushing the dissipation of the diode.  
You can select a drop with any of the 1N53**
series.

https://photos.app.goo.gl/FaydfesDmarD5fQB2

I've run it this way for hours.  No problems.

73 OM DE Dave AB5S