Hi A bit off topic, but here it is anyway.
If you pull the bulb from a "dead" FRK rubidium to replace it, most are indeed black. The replacement bulb is nice and clear. A FRK is not a 5065 and the "stuff" in the bulbs is likely not exactly the same soup of buffer elements. Bob On Mar 20, 2010, at 4:08 AM, Bill Hawkins wrote: > 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. > _______________________________________________ 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.
