[Milsurplus] MOSFET High Voltage Regulator Circuit

[mac]

Mack,

I take it you're using the original keying relay in the ARC-5 (K-53)  
which makes and breaks the B+ line to the oscillator tube and the  
cathodes-to-ground circuit on the 1625s.  Question -- How are you  
deriving the oscillator voltage, i.e., via a simple dropping resistor  
from your 600 volt HV supply?  The oscillator circuit in the ARC-5 is  
not particularly voltage sensitive but 600 to 200 on key-down is a  
heck of a swing and not too surprising you're getting some chirp.  You  
might try a tap off your PS bleeder resistor to supply the oscillator  
voltage and see if that cures the chirp problem.

If you determine you still need to regulate suggest you try a vacuum  
tube based electronic
circuit . Single 1625 series tube would handle the 400 volt drop at  
20ma you're talking about.  Circuits to be found in 50's/60/s ARRL  
handbooks.

Dennis D. W7QHO
Glendale, CA



On Dec 25, 2009, at 2:00 PM, Mack wrote (in part):

> Merry Christmas!
>
> I've almost completed my ARC-5 transmitter/receiver project but I  
> have a small amount of chirp when keying. I've confirmed it's the  
> 200V I'm feeding  to the oscillator plate not being stable. I can  
> eliminate the chirp by using my regulated bench HV supply........
>