[Milsurplus] DY-105/GRC-9X Relay K3

[Richard Brunner]

Ballast tubes do indeed respond in seconds, but much too slow to follow keying, and do take minutes to fully stabilize.  The selenium rectifier is used forward-conducting to utilize the knee of the curve to provide some voltage regulation to the 3A4 tube filaments.  Silicon rectifiers average 0.75 to 0.8 volts forward voltage drop, and I've used them successfully for low voltage regulation.  Three or four in series might work fine, but the voltage might be a bit too low, or a bit too high. It's worth trying.

Richard, AA1P 
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