[R-390] Rubidium Oscillator Questions

[Perry Sandeen]

Listers, 

A while back I bought a Lucent 3 piece GPS, - Rubidium Oscillator, and Xtal Oscillator set.  As of now I have had the Xtal oscillator running for several months and it seems very stable compared to the rubidium oscillator. I have yet to hook up the GPS receiver.

My questions are:

Does the Rubidium oscillator need to be on continuously or as some information on the net seems to imply that as soon as one gets a “lock” light that it is stable  to 10Mhz at E to the minus 12 or so?

Is there a limited operational life to the Rb oscillator so that it is better to leave it off until needed? The MTBF for the oscillator is 50 years at 25C but one does not know how long it ran and at what temperature it was used.

Does anyone have any knowledge or experience on how to phase-lock the GPS to either one or both?  The Rubidium osc data sheet states 0 to 8 volts for locking, with nominal being +2.5 volts.

I got two nice simple phase lock circuits of the web from James Miller G3RUH in England.  They are far less complex than the one from QST by Brooks Shera.

Right now one can buy the Lucent Rubidium from $60 to $150.  Should I buy one ore two for spares or do they have a limited shelf life?

I don’t mind getting inside the units and modifying them.

If anyone would need it I have two useful divider circuits.  One is divide by 1.5.  The other is a N1 divide 1 up to N+12. (Please reply off list.)

All this accuracy is, of course, is to be able to measure frequencies and drift of my R390A’s precisely.  (BTW Dallas Lankford got his R390A BFO drift down to 1 Hz per hour.)

Regards,

Perrier