https://www.febo.com/pipermail/time-nuts/2017-March/104374.html
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. DEP πθ°μΩω±√·Γλ WB0KVV _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.