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

[Matt Huszagh]

I measured the -2500V electron multiplier voltage as -1120V in this R7
(fully CCW) position. The manual indicates this should range from -900
to -2500V, so maybe it should be possible to adjust a bit closer to
-900V, but it doesn't seem so far off.

Matt

Matt Huszagh <huszaghmatt at gmail.com> writes:

> 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