[time-nuts] Re: 5061A HV Supply, et al.

[ed breya]

Great progress. If the pin 4 goes to near zero when the tube is active, 
then the ion current is high enough to cancel the test point voltage. 
Since you have the A18 can open, if you can now measure the voltage from 
pin 4 to the bottom of R5 (instead of ground), you should get an idea of 
the actual loaded HV out in this condition. Neglecting the tolerances of 
(especially) R4 and R5, the true HV out should be about 906 times the 
pin 4 voltage, if measured with a non-loading meter, or 926 times, using 
a 10 meg input R meter.

If you measure from the bottom of R5 to ground, you'll see the ion 
current signal. This negative voltage should be roughly the current 
times the sum of 75 k ohms (R6) and the resistance of the 10 k ohm (R7) 
parallel the monitoring circuit (where the "ION PUMP I" line goes). You 
can get an even better estimate of the HV out by adding (subtract the 
negative) this voltage, but just the simple look should be plenty good 
enough.


Ed