[time-nuts] Frequency standard

[Luca]

A stand alone ocxo, like the ones frequently used as time base in good
quality electronic counters, are very good, but you have to wait a couple
of months of continuous operation before they slowly end to drift. So you
can calibrate them with a good reference after this long period of start-up
and go ahead for many months or years with very good accuracy. But never
switch the ocxo off! :-).
Have fun.
Luca
iw2lje


Il giorno sab 26 gen 2019 17:01 DM <dgminala at mediacombb.net> ha scritto:

> Bob,
> Please advise the make & model of your counter, and if possible, the make
> & model of the OCXO it contains, or if you have the manual, the aging spec
> on the time base. It's entirely possible (probable) that the OCXO is
> already several orders of magnitude better than any HF WWV broadcast. BTW,
> higher frequency broadcasts are much more susceptible to atmospheric shifts
> than lower frequencies. That's why WWVB at 60KHz was used for many years as
> a traceable standard.
> How long has it been since its last real calibration (not beating against
> WWV, but properly calibrated)?
> I agree with the others who have advised in favor of a GPSDO. A second
> approach would be a Rubidium standard. Much more stable than a stand-alone
> OCXO, and they don't need an antenna. But, you would need to be assured
> that it's properly calibrated when you buy it. Ebay seller rdr-electronics
> sells Rb oscillators, and I'm pretty sure those they sell are properly
> calibrated before they ship them out. Good folks.
> Since you live in the LA area, surely there are other hams in the area who
> have the ability to properly adjust the time base in your counter. Get on
> the air and ask around. Might be someone just a couple of blocks away who
> has all you need.
>
>
> Cheers,
> Dave M
>
> ----- Original Message -----
>
> From: "Bob Albert via time-nuts" <time-nuts at lists.febo.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts at lists.febo.com>
> Cc: "Bob Albert" <bob91343 at yahoo.com>
> Sent: Saturday, January 26, 2019 12:06:43 AM
> Subject: Re: [time-nuts] Frequency standard
>
> Paul, thanks for your reply.
> You ask what I want to accomplish. Basically I just want to be able to
> calibrate the OCXO in my counter. I don't get a good enough signal from WWV
> and don't really have a proper method for adjustment.
> I listen to the highest froquency WWV I can hear, and these days it's
> probably only 10 MHz. I listen on a communications receiver to my counter
> and to WWV beating. As I watch the S meter, the pulsing gets slower and
> slower as I zero in, and at some point the pulsing is lost because the
> atmospheric fading masks it. That's usually around one fade every couple of
> seconds, for an accuracy of only about 1 part in 20 million. I want it
> somewhat better, but no way do I need it 100 times better. If I could set
> it within 0.1 Hz that would be fine - it would enable frequency measurement
> at 100 MHz with pretty good confidence, less so at 500 MHz. I used to be
> able to hear 20 and 25 MHz from WWV but those days are gone. Even then, the
> confidence level is a bit poorer than I'd like.
> So maybe a GPSDO would help but it seems the cost is out of proportion to
> my needs.
> Bob
> On Friday, January 25, 2019, 9:01:59 PM PST, paul swed <
> paulswedb at gmail.com> wrote:
>
> Bob
> The gpsdos will be far superior to the method you are currently using. I
> will guess 100-1000 times better and higher. I took a quick look at EBAY
> boy there are lot of them these days. We all have our favorites. Trimbles,
> HPs... But what would help is understanding your need. What do you want to
> accomplish.
> Regards
> Paul
> WB8TSL
>
> On Fri, Jan 25, 2019 at 9:05 PM Bob Albert via time-nuts <
> time-nuts at lists.febo.com> wrote:
>
> > Please excuse my ignorance but I have been trying to improve on my
> > frequency calibration.
> > I have always used WWV but when I try to get really close in frequency,
> > the beat and the fading are difficult to separate.
> > Someone suggested I get a GPSDO to refine my 10 MHz. I looked around and
> > have seen a few, mostly in the $100 range, but before I shell out fot
> > something I know little about I wonder if someone can give me a short
> > tutorial or at least some advice on what I need to do.
> > I live in Los Angeles so I imagine signals would be reasonably strong.
> > But what hardware and software do I need? I want 10 MHz to put into my
> > counter or, at least, to calibrate the time base in the counter. I
> prefer
> > the latter, since that means I won't have to receive GPS signals in
> order
> > to measure frequency. Most of the time I don't need really accurate
> > results.
> > I could run an outdoor antenna if needed. What receiver ought I look
> > into, how much budget do I need, and all the other questions relating to
> > this subject.
> > And finally, how much frequency error can I expect?
> > Bob
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>