> -----Original Message----- > From: [email protected] [mailto:[email protected]]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 _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
