[time-nuts] 4 KV Power Supply Recommendations Update

[J. L. Trantham]

The EC600 power supply is incredibly over built.  My goal is to 'reverse
engineer' the unit and come up with a schematic for all the boards.  I
predict it will be a while before I get this done.  However, it is quite
substantial and seems worth the effort.

BTW, the Ion Pump I rests about 26 not 36.  'Pilot error' on my part.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of paul swed
Sent: Friday, March 19, 2010 7:15 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 4 KV Power Supply Recommendations Update

Boy that is a nice supply. I see them for $129-160 on ebay.

On Thu, Mar 18, 2010 at 11:43 PM, J. L. Trantham <jltran at att.net> wrote:

> Just an  update on the status of the 5061A.  I started this thread on
> January 17.
>
> When first turned on, it pegged the Ion Pump I meter and, at glacial
speed,
> seemed to be 'pumping down', as judged by measurements of voltage on pin 3
> of the A18 +3500 VDC power supply.  I finally got tired of waiting and
> obtained an Electrophoresis Power Supply, an E-C Apparatus EC600, that
does
> 0-4000 V, 0-200 W, and 0-200 mA with any one of the three limiting as
> selected (thanks to Tom Frank for this suggestion, does anyone have a
> schematic for this unit?).
>
> After several weeks, it finally pumped down to the point that the internal
> power supply would allow the CS Oven to turn on but then the Ion Pump I
> would peg and take forever to pump down again.  After a few weeks of this
> along with further 'pumping', I decided to modify the internal power
supply
> to allow the supply to 'cut off' the CS Oven at 80 uA instead of the
> designed 40 uA by adding a 56K resistor across R6, the 75K resistor in the
> A18 +3500 VDC power supply.
>
> This allowed the CS Oven to come on, then the Ion Pump I meter indication
> would go up to the mid 40's, the  CS Oven would turn off, then the pump
> would pump down, and repeat the cycle.  It now rests at around 30 uA on
the
> Ion Pump I and all meter indications are now normal with the 'turn on'
> value
> on the Ion Pump I meter indication at around 36.  The Continuous Operation
> light now comes on and, seemingly, it is working.
>
> However, I don't think it is, at least not yet.
>
> I have the 5 MHz adjusted slightly high (about 5 mHz), as compared to my
> GPSDO, and the control voltage slowly increases, the frequency slowly
> decreases, passing through the GPSDO frequency and then the EFC voltage
> continues to increase, driving the frequency progressively lower.
However,
> it does not appear to 'lock' though I have not given it hours to show
that.
> My other CS units appear to 'lock' almost immediately once the Continuous
> Operation light comes on.
>
> It is behaving as if the 'Loop' is not closed even though it appears to be
> able to make the comparison of the 5 MHz to the CS, adjust the frequency
of
> the 5 MHz in the appropriate direction, but then fails to 'lock'.
>
> In order to get the 2nd Harmonic indication reasonable, I had to turn up
> the
> Loop Gain and put the A7 in 'High' gain.  I am suspicious that I have
other
> 'adjustments' to make but have not had time to pursue this in detail.
>
> So, it appears that I have more work to do.  However, at least as far as
> the
> Ion Pump goes, I think I have made progress.
>
> Thanks to all for the suggestions/discussion thus far and any further
> suggestions would be appreciated.
>
> Joe
>
>
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