[time-nuts] 4 KV Power Supply Recommendations

[Didier Juges]

For all the ion pumps I am familiar with (particularly one I built for an
airborne radar), the power supply regulation is intentionally very poor,
i.e. at the max specified current, the voltage should be down to something
like 500V or even less, otherwise the pump will overheat. The best curve is
not a constant current regulation, just a voltage that slopes down nicely
with the current.

In general, as long as the current keeps going down, even if slowly, you are
making progress. If it stops going down before it gets to the normal range
of the data sheet for that tube, you may have a problem.

Didier 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of J. L. Trantham
> Sent: Saturday, January 16, 2010 9:32 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] 4 KV Power Supply Recommendations
> 
> Sorry, TIA.
> 
> I was monitoring pin 4, not pin 3.  Pin 3 is -1.129 VDC which 
> would imply a current of 112.9 uA.
> 
> I will watch overnight and see what happens.
> 
> Any thoughts appreciated.
> 
> Joe
> 
> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of J. L. Trantham
> Sent: Saturday, January 16, 2010 9:02 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] 4 KV Power Supply Recommendations
> 
> 
> 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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