Hi According to the data sheet the X version of the 2400 has a TCXO in it. The “not an X” has an XO. “Setability” of the XO is <0.5 ppm and the TCXO is rated at 0.2 ppm. Maximum resolution on the device occurs with a 20 MHz input. That gives you +/- 0.05 ppm. The 200 MHz range is scaled by 10 and the 2.4 GHz input is scaled by 128. Neither one gives higher resolution than you get at 20 MHz. A source good to 0.05 ppm would only degrade the device by 1 LSB. A 0.01 ppm source would be adequate to ensure the final LSB is good. Any of the normal eBay telecom Rb’s would likely be good enough forever and ever, even without calibration. I have yet to see one that was off by > 0.001 ppm.
Bob > On Apr 12, 2017, at 10:01 AM, Tom Van Baak <t...@leapsecond.com> wrote: > > An update about this thread... > > It turns out that OP (Andre) would like the readings of his vintage Black > Star (UK) Nova 2400[X] 8-digit 2.4 GHz bench frequency counter to be accurate > and stable to the 8th digit. That's all. The internal XO or TCXO is not good > enough for that last digit or two. Not to mention the cal date is 1996. > > So the good news is that he is *not* embarking on a life-long project to > build his own atomic clock. This thread is just a newbie looking for a simple > answer to an accuracy / stability / calibration question. His counter has a > BNC for external timebase, so ... > > I think it would help him if any UK/EU time-nuts: > - have a 1e-9 or 1e-10 level OCXO to spare -- which he would have to > calibrate, or > - can help him locate a surplus telecom Rb -- inherently good enough that > calibration is not even required, or > - point him to a cheap newbie-friendly 10 MHz GPSDO -- if his environment > would make that possible and reliable. > > I would guess that a mere 8-digits of accuracy/stability should cost no more > than 100 these days. If you can help, please send him email, off-list. > > Again, OP is not looking for laboratory-grade accuracy or to build his own > atomic clock from scratch. It's just an 8 digit counter. > > /tvb > > ----- Original Message ----- > From: "Andre" <an...@lanoe.net> > To: <time-nuts@febo.com> > Sent: Tuesday, April 11, 2017 12:31 AM > Subject: [time-nuts] Re. DIY atomic "resonator" > > >> Hi all. >> >> As a first step, I wanted to build a specific hydrogen line (1.420 GHz) >> preamp. >> >> Seems that some fluorescent tube starters do emit a very brief burst at >> around 1.4 GHz >> >> during a specific portion of the initial switch-on surge when cold and >> actually observed this here. >> >> >> Also relevant, this same preamp can be used for GPS and if you're living in >> an RF proof flat >> >> with only one good radio station its hard to get any signal. >> >> >> Has anyone else either built an atomic clock around a bare Rb lamp module >> "core" or attempted >> >> to make a hydrogen maser? >> >> It would be a fascinating project to integrate SDR as these are (with >> modifications) very accurate >> >> and can be used to fine tune a lot of the oscillators etc with less hassle. >> >> >> Thanks, -Andre in Guernsey > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
