Really interesting thread. About a year ago on this thread the same discussion occurred. Several thoughts along these lines and frankly I know little accept for what I read here and online. I would agree the CS never runs out. Accept for one minor point. We tend to
huh?
get these things way beyond HPs end dates by many years. So is it really true? This threads a bit different then the last one. The last one described opening the internals and various effects from trying to refill the kettle. This would be the first insight that I have in the fact that the systems polluted perhaps. Regards
Paul, What I've heard is that the lifetime of the 5071A high-performance tube is around 7 years (when the cesium runs out) and the lifetime of the standard tube is up to 20 years (when the EM fails). There are other failure modes too so YMMV. Not sure about 5061A and other tubes. There are variations within the 5071A tube as well (including the short-lived turbo tube), so take this only as a rough estimate (but do see the chart in paper10.pdf below). As you may know the high-perf tubes have higher performance simply because they use a much higher flux of atoms (beam clock noise is a simple function of flux) and so they run out of "gas" proportionally faster. Like a candle burning twice as bright, or for you Neil fans, it's better to burn out than to fade away. But there's lots of data on this subject since most of the national timing laboratories use 5071A in quantity and they collect all the internal performance data that the 5071A makes available over the RS232 port. Some papers on the subject include: End-of-life Indicators for NIMA's High-performance Cesium Frequency Standards http://tycho.usno.navy.mil/ptti/ptti2002/paper10.pdf Maintenance of HP 5071A Primary Frequency Standards at USNO http://tycho.usno.navy.mil/ptti/1997/Vol%2029_06.pdf An Automated Alarm Program for HP5071A Frequency Standards http://tycho.usno.navy.mil/ptti/ptti99/PTTI_1999_649.PDF /tvb _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
