[time-nuts] 4 KV Power Supply Recommendations

J. Forster jfor at quik.com
Sun Jan 17 03:39:10 UTC 2010


Since it appears to be making some progress, I'd be tempted to just
continue. The pump rate of an ion pump varies with the current, so it
seems you are pumping, just somewhat more slowly than w/ the external
supply, as long as you are not overloading the internal supply.

If you don't have a lab supply, get an old transformer from some vaccum
tube gear and use the HV secondary to drive a Cockroft-Walton multiplier
to get to what you want. Pretty trivial to build these days. Put the
primary on a Variac to adjust the voltage.

BTW, a commercial supply at that voltage and current is going to cost
several hundred dollars.

FWIW,
-John

=============


> I have a 5061A That I am trying to bring on line and it pegs the Ion Pump
> I
> meter reading.  Measuring the voltage at pin 3 of the +3500V power supply,
> I
> get -0.275 VDC.  This is across a 10K resistor and suggests that CS tube
> current is 27.5 uA.  The voltage from the power supply with the tube
> connected is 2050 VDC and around 3100 VDC with the tube disconnected.
>
> It is recommended to connect the tube to an external 3500 VDC supply
> capable
> of 5 mA and let it run to see if the current will come down.  Having
> watched
> the voltage on pin 3 during the day, it has come down to -0.269 VDC and
> the
> voltage with the tube connected has gone up to around 2075 VDC.
>
> Any thoughts on a source for an external HV power supply for this
> application?
>
> Any thoughts on whether to just let it sit for a week or two to see if it
> 'pumps down'?
>
> Any thoughts on other things to try?
>
> Thanks,
>
> Joe
>
>
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