I have a 5061A that has been sitting in my shack for over 25 years. I keep it in standby, using just the OCXO as a casual reference, good for less than 1 PPM. I check the 1PPS output against GPS using a counter timer and tweak the front panel pot a few times a year to keep it spot on. When high accuracy is needed, perhaps a few times a year, Cs is activated and it typically comes up to satisfactory accuracy is around an hour - I usually leave it two hours.
Yes it consumes a few tens of watts, but I'm quite prepared to spend the few pence per day that costs :-) to keep the tube fully pumped and ready to go. I replaced the NiCd battery pack which was completely dead when I got the unit with a LM317 and float charged 24V lead acid batteries. Andy www.g4jnt.com On Thu, 5 Aug 2021 at 23:26, paul swed <[email protected]> wrote: > 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 > _______________________________________________ > time-nuts mailing list -- [email protected] -- To unsubscribe send > an email to [email protected] > To unsubscribe, go to and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] -- To unsubscribe send an email to [email protected] To unsubscribe, go to and follow the instructions there.
