> There's an HP 5062C closing on eBay soon! > > Corby > Thanks for the heads-up, Corby, even if it incited a bidding war. :) I bought it and got it working without much trouble. The problem turned out to be a resistor that had drifted high and crowbarred the oven-temp shutdown circuit.
Its cesium tube is elderly but still has some life in it. Beam current is about 0.47V at the test point (or 10 on the front-panel meter) with the mass-spec voltage at the first peak of 12.0V, and about 0.68V (~12 on the meter) with the mass-spec voltage at its highest peak, at 17.5V. Question: the 5062C manual has some contradictory instructions for setting the mass-spectrometer bias. Page 4-45 says the adjustment is "correct" when the beam current is at its lowest-voltage peak. Page 4-56 says "More than one peak may be indicated... Set MASS SPEC control for highest peak." Which is optimal? In my case I see a lot more beam current at the 17.5V peak than at the 12.0V peak, so I'd rather leave it at 17.5. The bad news is that when I tried installing my spare 5062C Cs tube, which I'd previously bench-tested successfully, the hot-wire ionizer filament opened up at some point during the periodic supply-cycling process that takes place until the ion pump current falls to its normal operating value. That sucked, because now I'll never know how the bench test results compare to actual performance in the clock. I don't see anything I might've done wrong when I installed the other tube. There was just too much O2 in the envelope, I guess... -- 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.
