Guys, remember what it said under Brian's picture in his senior yearbook: "Pick a side and I'll argue with you."
<ROFL> On Tue, Feb 19, 2013 at 7:41 PM, Brian Lloyd <brian-wb6...@lloyd.com> wrote: > On Tue, Feb 19, 2013 at 11:59 AM, Jerry Flanders <jefland...@comcast.net > >wrote: > > > I think the most important thing to remember in the Rb vs GPSDO debate is > > that without some other standard like a GPSDO or better to compare to or > > calibrate against, you never know that your Rb oscillator is actually > > on-freq. > > > Sure you do. Double check it against WWV. If it is within 1/2 Hz, the Rb is > locked and all is well. If it is unlocked it is very obvious because the > output frequency sweeps up and down by almost 1kHz. Tune in WWV and you > will KNOW it is unlocked. Once it locks and WWV is clear, it is working and > nothing it going to move it off 10MHz. > > > > The LPRO-101 has an adjustment to vary its freq. How would I know that > > adjustment pot didn't get jostled during shipment? > > > OMG, it could be .015 Hz off if it got turned all the way to the stops! Yes > the tuning limit is +/- 15 MILLIHERTZ. Remember, the frequency > determination is fixed by an electron transition in a shell of the Rubidium > atom. Unlike a crystal oscillator, it can't be very far off. If it locks up > at all, it will be within 1/2 Hz at 10MHz and quickly get better than that. > > > > Lastly, since we know the early Rb units were subject to failure due to > > aging of the Rb tube, how would I know the one I was considering has much > > life remaining ? > > > > Measure the lamp voltage. It is a pin on the connector. More than 7.5V and > it still has lots of life left. > > > > > Bottom line - I would HAVE to be able to check/calibrate it, but against > > what primary reference? > > > > And that is the point. You don't. Sure if you want to get it within 1 mHz > you could tweak it but even without any calibration max it could be off > after warmup is less that 1/100 of a Hz. > > Without a GPSDO to compare the Rb to, I think buying a Rb one would be a > > crap-shoot. After thinking it through, I skipped the Rb step and went > > straight to the GPSDO. > > > > But the GPSDO can be farther off during periods of poor GPS constellation > geometry. > > Bottom line: it pays to understand the technology. > > -- > Brian Lloyd, WB6RQN/J79BPL > 3191 Western Dr. > Cameron Park, CA 95682 > br...@lloyd.com > +1.767.617.1365 (Dominica) > +1.916.877.5067 (USA) > _______________________________________________ > FlexRadio Systems Mailing List > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > Knowledge Base: http://kc.flexradio.com/ Homepage: > http://www.flexradio.com/ > -- I can explain it for you, but I can't comprehend it for you. _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
