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

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@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