Corby, What I meant by "darkening" was that the photocell current and the second harmonic were at half of their minimum value given in the manual. I don't know what happens in the RVFR to cause that.
Why would a clear bulb have a low output? Can you refer me to something to read? I haven't found the right words to get Google to reveal any useful links. Several years after I bought the 5065 in 2003, there was not enough second harmonic to maintain control, saturating the integrator. So I followed the cure for cell flooding given in the manual. After 10 days the second harmonic stopped improving at about 10 on the meter. Something appears to be microphonic in the photocell. A sharp tap to the case causes the second harmonic to peg the meter briefly. A Tracor 308 does something similar, but it doesn't have a meter for anything but error - the red Unlocked light comes on briefly. Perhaps my brain is darkening with age . . . Bill Hawkins -----Original Message----- From: Corby Dawson Sent: Friday, March 19, 2010 4:11 PM To: time-nuts@febo.com Subject: [time-nuts] HP 5065A rubidium lifetime I have been repairing HP 5065A for over 20 years and have never had a failure due to "darkening" I did have one Efratom unit years ago that the lamp envelope had darkened so much it was unusable. Not sure if the is the "darkening" referred to? The "killer" 5065A failures are oven failures that melt the insides, and a bulb that has a very low output. (The bulb envelope is still nice and clear in these cases.) The bulb can be replaced with some Efratom ones with varying results. Also cell flooding can occur after long storage and/or storage in high temperatures. This is easily cured by applying 5VDC thru a 5ohm 10watt resistor to the TED (thermoelectric device) in the receiver for 6 days or so. Corby Dawson ____________________________________________________________ Diet Help Cheap Diet Help Tips. Click here. http://thirdpartyoffers.juno.com/TGL2141/c?cp=NQ-DyajjqFQSe1WjsW9ZnAAAJ1ABLZ FyqoH-WnHH1GJ345whAAYAAAAAAAAAAAAAAAAAAADNAAAAAAAAAAAAAAAAAAAYQAAAAAA= _______________________________________________ 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. _______________________________________________ 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.
