[time-nuts] HP5061 offline management.

[paul swed]

Was talking with another time-nut on the best way to use the HP5061 Cesium
to protect the tube. I have read over the years that some people let the
system run but with the CS oven off.
This consumes 19.4 watts or about 14KWH/month.
But has the advantage of a nice local reference and the tube is pumped down.
I however leave my units completely off and run them every 2 months. The
downside of this is that when the ion pump clears the tube when the CS oven
is turned on there is a crud burst and the ion current reading can go
significantly up. Then has to pump back down a number of times.
There is a better way.
Leave just the 3500V supply run. Disconnect it from the internal power add
a resistor and cap powered by a external switching wallwort in the 1 watt
range. Brand new meanwell  units are $11. These are medical grade not that
its required. The resistor is about 470 ohms a 1/4 watt. Dropping 24V to
19V. Use a 470 uf cap on the side of the resistor connected to the 3500V
supply. Ground the negative to the chassis so the I pump meter works.
Taking this approach drops power consumption to .31 Watts. Larger higher
current supplies will draw higher power wasting idle currents.
I was going to drill out a hole and mount a small powerjax. But just really
didn't so brought out a pigtail to a powerjax. No change to the chassis.

Operating this way the 3500V supply is always running. When I want the CS
to run I plug the original power cord in. After the ovens warm up in
business. No waiting for the ion pump to do its job and the best benefit No
crud burst as the tube is clean.

The same adapter will easily power many 3500 V supplies. I have 3 5061s
that will be modified. Good news each 5061 consumes about 10 ma.

Lastly 5061s do make noise around 2 KHz somewhat annoying.
Its easy enough to use a wall time and run just at night and switch the
supply on when actually using the Cesium. But a timer just multiplied power
consumption a lot.
A greener HP 5061.... Did I just say that. Sorry.
Regards
Paul
WB8TSL