[time-nuts] Fwd: HP5061B Ion Current
Donald E. Pauly
trojancowboy at gmail.com
Sun Mar 26 18:42:04 EDT 2017
We continue to try to achieve lock on our latest HP5061B acquisition.
We found that the -2,500 supply would only come up to -780 V under
normal 55 Meg multiplier load. When we pulled off the HV lead to the
beam tube, it came up to only about -1,500V. After another horrible
desoldering job, Q2 collector waveforms were essentially normal. We
found a near open C1 which is 47 μFd at 35 Volt electrolytic was open.
This caused massive spikes on the bypassed +18.7 line. We replaced it
with a tantalum. This brought it up to normal -2,700 V for full
clockwise beam adjust on R7.
Next we found that the +3,500 supply was only up to 1,000 V with
normal ion current load. We expect to find the same problem on this
supply. See http://gonascent.com/papers/hp/3500top.jpg. C1 cannot be
seen in this photo. Ion current was only 15 μA because of the low
supply voltage. I will have another post on what we found about
electron multiplier voltages.
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