https://www.febo.com/pipermail/time-nuts/2017-March/104374.html
The design on the voltage and current limiter is complete but not breadboarded yet. We are getting a little more time on our HP5061B beam tube after beefing up the +3,500 Volt power supply. We have the frequency control R4 turned all the way up to 1900 cps with beam tube ion pump load. We have a shunt across the ammeter so it can measure 100 μA full scale instead of 50μA. We dare not disconnect the load because voltage limiting is not operational yet. Continuous lock light is lit. Note that lock is normal at over 3 times what the book said was normal cesium turn on point. If we could go to +3,500 Volts, the current would likely be 100 μA. I calculate that lock would be normal at 1 mA ion pump current. time μA voltage 08:46 56 3,620 09:46 70 3,400 11:25 72 3,360 12:58 76 3,300 We just got in our second HP5061B yesterday It's ion current was only 14 μA but we haven't checked the voltage on the +3,500 V supply yet. It appears to have a problem with the -2,500 V supply. πθ°μΩω±√·Γλ WB0KVV _______________________________________________ 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.