[time-nuts] Fwd: HP5061B Ion Current
paulswedb at gmail.com
Sun Mar 26 19:48:34 EDT 2017
Really good pix on the inside of the 3500V module. So the opening of the
can is the typical lots of heat and pry it open approach right?
How about a good pix of the 2500 Volt module?
On Sun, Mar 26, 2017 at 6:42 PM, Donald E. Pauly <trojancowboy at gmail.com>
> 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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