[time-nuts] 5071A tube evaluation

corby d dawson cdelect at juno.com
Sat Dec 22 12:09:02 EST 2007


If the unit has been stored for years then the first time it is plugged
in the ion pump current displayed will be high and the Cs oven will be

When the ion pump current drops the oven will turn on momentarily and
outgas. This will cause the ion pump current to rise and cut off the oven

This cycle will continue (sometimes for many hours) until finally the
oven will stay on.

The after 15 minutes or so the unit should lock.

Now monitor the electron multiplier voltage for a week or so. It
hopefully will start out well below 2500 Volts and remain stable.

If should remain stable and not exibit a constant rise (over a week or
so, it can show slow variations over months).

The amplifer gains should also be low. (for the default starting values
look at the gains before the unit warms up.)

A depleted tube will show a rapid rise up to the maximum voltage and
after the amplfier gains also rise to the top to compensate the unit will
fault out.

If the mainframe has a problem or you have a tube not in an instrument I
have a stand alone Cesium tube tester that I charge a small fee to test
tubes in.

Hope this helps,

Merry Christmas!

Corby Dawson

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