Hi all, After lurking below sea level in Amsterdam, allow me to surface with a specific question... In short, I am a typical Electronics Engineer with too much curiosity in too many subjects and a chronic shortage of time.... Metrology is one of my fascinations, ranging from a solid invar standard meter (salvaged from the skip at work) to a still aging HP106B and a Z3816.
Right now I managed to get a 1971 HP5061A (ser. 1124A00503) up and running. I recently bought it from Robert Deliën, who in turn had obtained it shortly before from Erik Kroon, both subscribers to the list too. The instrument originated from the Dutch Standards Bureau and contained what appears to be the 2nd tube in its life span (ser.nr 1749 of series 1240A), judging by the notes on the operating record. Robert had already repaired the HV power supplies and oven controller, but lacked the time to finish the job. To cut a long story short, after a day I had it in operating mode and locked, but after a few hours the control voltage wandered off again. It boiled down to a tin whisker on one of the intermediate pcb's inside the 5 MHz OCXO (00105-6013). It shorted the -EFC voltage when fully warmed up and cost me several hours of sleep and a couple of days to locate it and repair the darn thing. Probably this fault was the reason for decommisioning the 5061A, as the tube shows a healthy beam current at low temp. Now it is rock steady whining away in more or less constant phase shift to a 58533A at work. Next step would be killing that 2 KHz whine by supplying 5 volt DC (through a PID controller with SS switch at a 1 second cycle time) to the heater. This particular tube has a type T thermocouple built in, very handy to check the Cs oven's exact temp and to control it. Hence my questions: Will heating the Cs oven with DC have any influence on the C field? Can anybody provide me with, or point me to, the 5061/5062 circuit of the later DC heater? I have the pdf''s for the first series up to 1740A prefix. The 2 kHz inverter powers the ionizer wire, the heater and the original neon choppers in the opamp module. Taking out all but the ionizer will drastically reduce the audible noise. I can imagine that feeding the ionizer with DC would disturb the EM entry focussing, so I'll leave that in for now. I remember reading somewhere down the list that High Performance tubes ran exclusively on DC. A second "donor" unit I have, has a HP tube (#1908A00865) that still shows the tap settings for the AC controller. Haven't checked that tube yet, it has a history in the German FTZ. Thanks in advance for the trouble of answering my question, 73, Hans PA0LED _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
