[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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