[time-nuts] Troubleshooting a 5061A Cesium Standard

[Scott McGrath]

All,

Recently purchased a 5061A with a option 004 beam tube yes, yes I know
about the lifespan of these tubes (anyone have any spares for sale?)
however the tube looks MUCH newer than the 5061A Ion pump is about 10
at turn on and drops to near zero after an hour or so.

Hot wire ionizer resistance shows correct resistance varies between
.6-.8 on a fluke 83

The bad

>From the -2500 V power supply test point I read  - .210V which appears
to be incorrect as the electron multiplier voltage on tube is -1691 V
I have been thinking about replacing the R31 and R33 resistors with 20
turn pots adjusted to the tube values as the resistors do not seem to
match the tube values.

21.41Khz @ 1VRMS injection to LF coil  does not affect beam current

Cs Oven 25
Crystal Oven 30
Ion Pump 0-1
Beam 0-1
Mult (Off the scale)
Error reading 0
Control reading 0
2nd harmonic 0
5 Mhz 35
1 Mhz 0 (Think this is a metering problem as 1 MHz is available at the
output at specified voltage)
100 Khz 35

5 Mhz Oscillator is on target it's within 6E10-10 of my Rb standard
which according to my Austron 2100 has an offset of 3E10-12

Based on this information where should I begin my troubleshooting efforts?