[time-nuts] hp5061a/b no I beam current

paul swed paulswedb at gmail.com
Tue Oct 20 01:32:20 UTC 2009


I think I am on the trail of the issue.
Several things I now understand.
Somethings up with the -2500 supply its not the photo multiplier.
The regulators feeding perhaps4-6V to it and thats about -1000 not 2000
To make 2083 volts needs 15-16.
The voltage at the test point shows nothing but ringing so impossible to set
the em voltage by that test point and perhaps what I have been seeing
thinking it was correct. Also suspect someone else did the same.
I can directly read the V. I have the module out of circiut now.

I would be tempted to manually set the v with an external supply just to see
if the standard comes online or at least gets I beam current of some level.
It could also be the regulator feeding the inverter.
But big question what should the rough voltage be that feed the module.
15-16 sounds somewhat high to me since the supply is 18V.
Appreciate your thoughts on thois and the use of an ext LV supply to feed
the em inverter.
Thanks

On Mon, Oct 19, 2009 at 6:23 PM, John Miles <jmiles at pop.net> wrote:

> > -----Original Message-----
> > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> > Behalf Of paul swed
> > Sent: Monday, October 19, 2009 6:48 AM
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] hp5061a/b no I beam current
> >
> >
> > John,
> >     Thanks and thanks for your comments on your experiance.
> > Yes the readings look good. Oven is at the temp it should be according to
> > the notes.
> > I do see the ionizer dc offset was maxed at 15v or so. That seemed odd.
> > Does look like about 1 v diff on the ionizer. Whats the
> > resistance supposed
> > to be roughly 1-2 ohms???
> > I noted that if I increased the multiplier voltage quite high I
> > actually saw
> > a bit of I but it does not happen all the time and I do not want to keep
> > doing that.
> > Also another strange note the multiplier voltage was supposed to
> > be at -2083
> > yet it was set to -1606.
> > Lastly the vac is 0 it had bee about 50+ but seemed to pump down.
> > But 0 seems way to good to be true.
> > Thanks again
>
> The ionizer filament is OK, with 1-2 ohms.  Its supply is OK at ~1 volt,
> and
> the zero vacuum reading is not a concern -- it just means what it says, the
> vacuum is that good.  The Datum tube in my 5061A reads very close to zero
> ion-pump current, and its mass-spec voltage also wants to be set near the
> maximum end of the range.
>
> But the weird EM voltage doesn't make much sense.  Either there is
> something
> wrong with the main supply or the ground reference for it (how's the ripple
> look?  any open filter capacitors?), or someone else was playing with it in
> an attempt to get the tube working, and they cranked the control back to
> minimum when they gave up.  I'd lean towards the latter explanation, for
> better or worse.
>
> One other thing you could check is the Cs oven temp.  After running it for
> a
> few minutes, power it down and compare the resistance across the thermistor
> leads to what's printed on the tube label.
>
> -- john, KE5FX
>
>
>
>
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