https://www.febo.com/pipermail/time-nuts/2017-March/104374.html
I could not figure out why the A15 Ion Current monitor would not let the cesium oven turn on with ion current under 25 uA. At the time we had no way of measuring the +3,500 ion pump supply. We bought some 200 Meg resistors and made a crude HV meter to feed our 10 Meg Fluke 77. The supply had sagged to 2000 Volts with that load. This prevented the ion pump current monitor from energizing the cesium oven. KB7APQ unsoldered the can on the 3,500 Volt supply with suggestions from WB4BBP. It is a horrible design and we studied it. R4 is set at the factory to produce 3,500 Volts with no load. It runs at 704 pulses per second and sags badly with the slightest load. This prevents the ion pump from clearing the gas in the beam tube. The pot core transformer is plenty big that it appears that the supply can put out 5 mA at 3,500 volts. This allows it to replace the external supply recommended by HP for gassy tubes. It looks like that it can run at 10 kc with existing pot core transformer. The pulse width looks like it can be doubled as well. This allows for a 30 to 1 increase in output power. A small circuit board will regulate the voltage as well as limit the current. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.