This one "110 ?C" should read "110 degree C" Ulrich Bangert
> -----Ursprungliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Ulrich Bangert > Gesendet: Mittwoch, 12. Marz 2008 07:21 > An: 'Discussion of precise time and frequency measurement' > Betreff: Re: [time-nuts] Rubidium Oscillators and Racal 1992 > > > Gentlemen, > > I would like to place emphasis to the fact that the so called > "lamp voltage" is just the operating point of a regulation > loop in which the lamp's health is ONE of the involved > parameters, exactly as Antonio's experiments verify. > > Within the lamp a plasma ignition is excited by means of an > external electromagnetic field. The field's frequency as well > as the lamp's temperature (which is in the near of 110 ?C) > are important parameters for the quality of the plasma > ignition and for where the operation point of the loop is. > > When Antonio was "Adjusting the capacitive trimmer solid with > the lamp assembly (and) the lamp-V ranged from 1.5 to 6.5 V" > he demonstrated the dependance of the operation point from > the exciting field's frequency. Not sure whether the LPRO > also has, but the FRK-Ls have trimmers for the temperature > setpoint of the lamp's temperature controller. Would he have > changed that he would have observed a similar dependance. And > when "the lamp-V oscillates within 10 milliVolt basicly > according to ambient temperature" this is simply the effect > of the temperature controller's inability to control the > lamp's temperature perfectly despite of ambient temperature changes. > > So a better phrase would be that the lamps voltage is an > indicator of the lamp's health IF and ONLY IF everything else > is sane. Don't blame the lamp before you have checked the > temperature and the exciting field's frequency. > > I am stressing this a bit because exchanging the lamp is not > exactly easy! While it is a snap to remove the lamp toghether > with the lamp holder (a small metallic part that makes the > whole thing look like an ordinary bulb) the lamp itself > (which is ONLY the glas compartment) is glued (?) to the lamp > holder and in order to exchange the lamp I guess you will > need to destroy the current one and the glue in the new one. > > Has anyone of you already performed that action or can give > an clue which adhesive is suited for that purpose??? > > Best regards > Ulrich Bangert, DF6JB > > > -----Ursprungliche Nachricht----- > > Von: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] Im Auftrag von [EMAIL PROTECTED] > > Gesendet: Dienstag, 11. Marz 2008 15:31 > > An: time-nuts > > Betreff: Re: [time-nuts] Rubidium Oscillators and Racal 1992 > > > > > > I purchased on ebay four rubidium LPRO and I'm quite > > satisfied with them. The lamp-Volt parameter (which is an > > indication of the lamp's health) was > > respectively 8.4, 7.95, 6.8 and 5.1 Volt. > > When an LPRO leaves the factory its lamp-V is around 12V. A > > drop of up to 3 V > > would be expected in the first year of operation, but after > > that the voltage > > decay rate slows down dramatically. > > According to the manufacturer, when the lamp-volt drops down > > to 3 V (this is > > expected in not less than 10 years) the unit needs > > maintenance. I've used the worst unit (5.1V) to make some > > tests in order to get more > > familiar with them. Adjusting the capacitive trimmer solid > > with the lamp assembly > > the lamp-V ranged from 1.5 to 6.5 V. It remained locked even > > when the lamp-V was 1.5V. All of the units showed a VCXO > > steering voltage in the middle of the usable > > range. > > The unit with 7.95 lamp-V is running continuously since 40 > > days. I'm monitoring and recording every 15 seconds the > > lamp-V, the VCXO V and the temperature of > > the heatsink at the baseplate (you should provide a > > heatsink). After a few days > > of stabilization (in wich the lamp-V showed a tendence to > > increase, may be following > > a long period of no operation) the lamp-V oscillates within > > 10 milliVolt basicly > > according to ambient temperature, and I've not yet noticed > > any decay in the averaged data. This is a simptom of good > > health from which one could expect some 10 more > > years of continuous operation. > > I'm measuring and recording at the same time its frequency as > > read by a > > Racal 1992 with option 04E (OCXO). Of course the observable > > drifts would came > > from the Racal oscillator. > > Well, I would spend a few words on the Racal too. > > I'm making the measurement at a resolution of 1 part in > > 10e-10 (gate time 10 seconds, good ADEV for both units) and > > often I' can't appreciate any drift at this level on > > a daily basis. In averaged data, the drift is something like > > 2*10e-11 per day > > (Racal specs less than 5*10e-10 per day). > > By the way, speaking of the Racal 1992, I have to say that > > mine is the military > > version 02M. I have two of them, and a friend of mine another > > one. None of the > > three units showed the problem with pushbuttons. May be the > > military version used different materials? Anybody knows? > > The unconvenience with the 02M version is that it uses a > > military GPIB language (MATE/CIIL), and I had to get familiar > > with it. Antonio I8IOV > > > > > On Mon, Mar 10, 2008 at 10:12:46PM -0500, Brian Kirby wrote: > > > > For maximum stability, the rubidium should be run continuous. > > > > > > > > I lost a lamp in a FRK-L last summer. The unit had been > > running for > > > > 9 > > > > years continuous - and I was the second owner. It was > > used at a LORAN > > > > site previous, I am sure they probably ran it continuous, > > for the same > > > > reasons. > > > > > > According to various spec docs I have seen, many of the telecom > > > oriented rubidiums (such as the LPRO and FE series) are > > designed for > > > between 15-20 years lamp life continuously on... so running > > one that > > > way is not likely to use up available life quickly unless > > the unit already > > > has lots and lots and lots of hours on it. And they > > aren't absurdly > > > expensive on Ebay these days - bet a new bulb (if even > > available) is > > > almost as much as a used but working rb off Ebay. > > > > > > > > _______________________________________________ > > 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.
