<EWKehren@...> writes:
> > Having had more than ten FRK's and M100's on my bench and once locked none > where as low as any thing in E-9. What you should buy is a ubox for $ 16 > shipping included and you will with your counter be able to get better than > 1 E-9 for testing. > Bert Kehren > > > In a message dated 8/10/2014 2:30:50 P.M. Eastern Daylight Time, > ed_palmer@... writes: > > How did you make the measurement that showed a 0.8 Hz difference? What > are the specs on your Racal reference? When was it calibrated and > against what standard? That will tell you how much confidence to put in > it's frequency. > > As others have said, an FRK isn't a primary standard and should be > calibrated against a primary standard. However, 0.8 Hz is an error of > 8e-8. I don't believe it's possible for a Rb standard to lock and be > that far off. > > > > > Sorry if dumb questions, but just starting my quest for "time nut" > status!!! > > > > Thanks > > > > Peter > > G0RSQ > _______________________________________________ > time-nuts mailing list -- time-nuts@... > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > Thanks for the interest in my questions. Unfortunately the FRK has now decided to stop locking, so I need to go back to fault finding. I suspect the problem is with the "hunting" of the 10Mhz ref oscillator, as I get a swing of over 300Hz, which I am sure is far to big. The manual is confusing, as sometimes it talks about a swing of +/- 20 Hz, and other times +/- 1Hz... In answer to the questions:- After the FRK locked up, I connected it to my Racal 1998 counter, which has the external reference coming from a Racal 9480 mainframe, which is running its back-up internal ovened frequency reference (last calibration was about 5 years ago before i acquired it!) (it is this that I want to connect the FRK to as its main frequency source). I had a reading which was 0.8 Hz down on 10 MHz. I left this for about 1 hour to see if anything changed, but it did not. I then connected both oscillators to the input channels of my oscilloscope (Tek 2465B), triggering of the FRK, and saw a fairly rapid movement on the ovened waveform. All this indicates to me one of the references is out by 0.8Hz. I understand that rubidium is not a primary frequency standard and the output is synthesized, but was hoping that some clever technique was used to ensure a certain level of reliability. How far off frequency could one be and still lock? I do have an old "Off Air" standard frequency receiver (similar to a "quartz lock") which receives "Droitwich" on 192KHz, which gives a 10MHz output. However I am unsure how suitable this is for calibrating my FRK. I will give it a try this week, and see how it compares with the FRK. I also have a Trimble (not a thunderbolt) GPSDO bought from a seller in china, which I am yet to set up and try, so maybe this will be my next project (but maybe I will be asking the same questions when this is running!!!!). Thanks for the help and comments Peter G0RSQ _______________________________________________ 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.
