That FE-5680A (the "non-programmable" one) is the same as the 2 units I have - I have seen the "heat a lamp with a heat gun" trick before when I was playing with the FRSs - but in this case the actual lamp is fine - the problem seems to be with the absorption cell (or possibly the other one, which I suspect may be a filter). I've never seen these go bad in any of the other units I've seen. I guess I could try re-consolidating the Rb into that little pinch and see what happens.
I'm also not sure the heat gun trick is going to be very practical for the lamps on these units - the RF exciter coil seems to have been stuck onto the lamp with RTV and then the whole assembly stuck into the lamp housing using a big dollop of RTV at the back. You possibly could release the lamp, but it looks like you would have a good chance of destroying the drive coil in the process. I've also been trying to figure out what the RF architecture of these units is - it certainly seems to be different from the older ones; for a start, the DDS chip is now an integral part of the control loop and is generating at least part of the modulation used to interrogate the resonance cell (the DDS is clocked with 20MHz and generating ~5.312MHz, but the Fselect pin is being driven by a 416.6...Hz square wave coming from the Xilinx PLD and it's output is mixed with the 60MHz from the VCXO and fed to the snap diode on the physics package multiplier assembly. Once I get a better handle on how it all works, I guess I should write it up for the benefit of anyone else trying to fix these things - but right now it's in the "unannotated photographs and cryptic notes" phase :) Regards, Pete On Mon, Oct 31, 2011 at 8:32 PM, J. L. Trantham <[email protected]> wrote: > That's it! Plus, more information. > > I knew most everyone would be better organized than I am. > > Joe > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Mark Detering > Sent: Monday, October 31, 2011 7:22 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Fwd: FE-5680A Physics package > > > Here is a page that has some information on the FE-5680. > http://vk3um.com/Rubidium%20Intro.html > Near the bottom the is a link to an article by VK3GJM that talks about > rejuvinating Rb lamps. This may be of help. > >> Peter, >> >> Somewhere, I have read an article about 'resurrecting' a 'dead' Rb >> bulb. I think it was done with heating but I do not recall. I >> probably have the article squirreled away somewhere and I can probably >> chase it down if someone else on the list does not come up with the >> link first. >> >> Are you familiar with what I am talking about? >> >> Joe >> > > > _______________________________________________ > 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. > > > _______________________________________________ > 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. > _______________________________________________ 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.
