[time-nuts] HP 5061: Unable to adjust beam current to less than 46nA

[Matt Huszagh]

Hi,

I've got an HP 5061 that appears to have a good tube: it locks easily
and I measured the signal-to-background as 3.76 and signal-to-noise as
1866 (standard tube).

However, one thing that surprised me a bit is that I wasn't able to
adjust the beam current for a reading of 25nA when following
"5-205. Beam I Adjustment" in the manual. The lowest I can get it is
46nA when the Beam I Adjustment pot (A15R7) is fully CCW. I also
confirmed this reading is correct with a multimeter. I measured the
A15Q8 emitter voltage to be 11.9V when R7 fully CCW, which seems to be
ok judging by the indication in the manual.

I imagine this may not be a problem: high beam current is a good thing,
right?. Thoughts? Any other tests I should perform?

In case it's useful, the beam health measurements were Vp=4.6, Vv=1.1,
Vb=0.93, and V3400: 1.5.

Thanks,
Matt