[time-nuts] Fwd: HP5061B Ion Current

Donald E. Pauly trojancowboy at gmail.com
Fri Mar 24 17:38:31 EDT 2017


The design on the voltage and current limiter is complete but not
breadboarded yet. We are getting a little more time on our HP5061B
beam tube after beefing up the +3,500 Volt power supply.   We have the
frequency control R4 turned all the way up to 1900 cps with beam tube
ion pump load.  We have a shunt across the ammeter so it can measure
100 μA full scale instead of 50μA.  We dare not disconnect the load
because voltage limiting is not operational yet.  Continuous lock
light is lit.  Note that lock is normal at over 3 times what the book
said was normal cesium turn on point.  If we could go to +3,500 Volts,
the current would likely be 100 μA.  I calculate that lock would be
normal at 1 mA ion pump current.

time   μA voltage
08:46 56  3,620
09:46 70  3,400
11:25 72  3,360
12:58 76  3,300

We just got in our second HP5061B yesterday  It's ion current was only
14 μA but we haven't checked the voltage on the +3,500 V supply yet.
It appears to have a problem with the -2,500 V supply.


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