[time-nuts] Is there a good web page introducing ADEV?
I'm looking for something for non-nuts, the general idea without any complicated math. Deep in ntpd is logic to adjust the polling interval, attempting to find the bottom of the V. It's hard to describe that to somebody who doesn't know about ADEV. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Brand new OCXO/TCXO reccomenations
I'm hoping some of the list are familiar with the newer currently-available oscillators available from the distributors. Some background: I'm starting to play with a short-term 1PPS holdover application, mainly to cover up brief GPS signal loss events (a few minutes at most). Since I may at some point want to make numerous copies of this, I'd rather start with a new oscillator as opposed to digging through the junkbox or buying surplus. Lower cost (<$100 ideal, lower is even better) and power consumption is good. My short-term stability requirements indicate to me that I'm probably looking for an OCXO instead of a TCXO, although it looks like some of the best TCXO's out there are in the range which will work in most cases (50ppb over temperature (or better)). I suspect I'm going to handle the holdover in a FPGA. As such, I don't think I'm going to bother trying to voltage control the oscillator. Seems like it will make the overall circuit simpler and I don't have to worry about a whole bunch of control circuit temperature compensation. I've dug through enough datasheets at this point, my eyes are glazing over. I also know that the spec sheets are only part of the story when it comes to oscillators. I also have found over the years that often the part I'm looking for (that 20ppb Temperature-stable TCXO for a reasonable price) exists if you know the vendor to look at... So any specific recommendations or pointers toward a brand/type would be appreciated. -- - Forrest ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.
Thanks Tom- I really appreciate your comment. I've studied your website closely on this topic. I'm really in awe of the 860x models some of you have access to 8607, 8608 models some with options! I'd probably be considered a newer school timenut/voltnut but... I even collect Nixie tube frequency counters... Separate topic but wow I just love cold cathode display technology and mixed with frequency... well dekatron counters too. Props to Jim for making BVA available here before putting on the auction site! I have mad respect for that. I've found some of the best people here. Best Regards, Bill On Wed, Sep 23, 2020, 4:29 PM Tom Van Baak wrote: > James Robbins wrote: > > > Oscilloquartz BVA has been sold. > > To the time nut who ended up with this BVA -- do not worry if it looks > like it is broken when you power it up. These oscillators take their > time to warm up. Here is a test I did last year on a similar BVA > oscillator: > > "Oscilloquartz 8600-series OCXO warm-up" > http://leapsecond.com/pages/osa-warm/ > > /tvb > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.
James Robbins wrote: > Oscilloquartz BVA has been sold. To the time nut who ended up with this BVA -- do not worry if it looks like it is broken when you power it up. These oscillators take their time to warm up. Here is a test I did last year on a similar BVA oscillator: "Oscilloquartz 8600-series OCXO warm-up" http://leapsecond.com/pages/osa-warm/ /tvb ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] More GPSDO measurements
Hello time-nuts, I'm back with some more data of my GPSDO. The OCXO meanwhile has settled in a bit and its drift has slowed down considerably, time to make some more measurements. Find attached the ADEV graph of a 24h run using the TAPR TICC connected to the 1PPS output of the GPSDO. I was able to use a higher time constant now for the PI loop (500 seconds). For comparison, I've added again the Trimble UCCM-P trace I've shown before. But with what I know now about how long OCXOs take before they settle again after being off for an extended time, I'm not sure I'm doing it justice. The Trimble OCXO that's inside is likely much better than the poor, mishandled MV85A I'm using in my own GPSDO, but I didn't give it more than a few days to settle. I'll really have to do a parallel measurement run at a point to subject them both to identical conditions. Regards, Matthias On Donnerstag, 3. September 2020 09:46:23 CEST Matthias Welwarsky wrote: > Hello, fellow time-nuts. > > finishing the next PCB revision of my GPSDO cape project, after assembling > some components that JLCPCB SMT service doesn't stock I did a test run to > compare it to the previous revision. The measurement setup is identical to > my previous test, 53131A with MV89A OCXO, frequency mode with 2s gate time. > > There are only a few changes, I routed the OCXO power rail through an LC > filter to decouple it a bit from the digital noise generated by the > Beaglebone. Another change was to add a 1PPS output, using an additional > timer of the AM3358 in PWM mode, clocked by the 10MHz OCXO output. This > will give a nice, stable 1PPS signal. > > I also changed the analog output stage to be just a unity gain buffer for > the DAC instead of a 6dB gain stage. This is probably the most notable > change as it doubles the DAC resolution. It also shows in the results, see > the attached picture. Green curve is the new rev2 board, blue curve is the > best run of the previous revision I could do, magenta is the Rb GPSDO. > > Unfortunately I did a bad pick with the OCXO. I bought three MV85 OCXOs from > Ebay, two of them obvious fakes, the third one appeared to be genuine and > it seems to be quite OK with regards to short term stability, but it drifts > heavily and doesn't seem to find equilibrium. This means the GPSDO needs to > kick it back on track quite frequently, preventing using of larger time > constants (now 300s). But still, the overall stability is better than the > previous revision, which I find quite remarkable. I'm pretty sure that I > could now beat the noise floor of the measurement setup with a working > OCXO. I've ordered a brand new OCXO from Digikey, I have another PCB > revision to launch which will hopefully be the final one and the new OCXO > will then go on the final PCB. The final PCB revision will feature a > slightly more elaborate analog output stage which will allow down-scaling > and biasing the DAC output to further extend the DAC resolution. > > Regards, > Matthias ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] BVA 8600 Available for sale: Link to Dropbox photos/ADEV plot.
Jorge, The longer Tau (BLUE) was measured against an excellent HP5065A Rubidium. The shorter Tau (Red) was measured against an excellent FTS 1200 Quartz. Hope that helps. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Thunderbolt E failing
I received one of these thunderbolts. It seems to work (currently handicapped by an inadequate antenna) and is labelled P/N 48050-61 D/C 0331 on the outside. The firmware is 3.00 and the OCXO labelled 37265 10.00 MHz B11859-17495 0310. On Sat, Sep 12, 2020 at 10:43 PM Adrian Godwin wrote: > Thanks! > > The one I've seen pictured most often comes in a (I think) slightly lower > gold-coloured (alocromed) case. > e.g. http://www.sydneystormcity.com/TrimbleThunderboltGPS.jpg > Is that any different ? > > I did order the one from my link so will report on any markings. The > vendor mentioned part 48050-61 but as you say, that seems to be common to > all of them. > > > On Sat, Sep 12, 2020 at 10:14 PM Bob kb8tq wrote: > >> Hi >> >> The unit your link points to *is* the “classic” TBolt that showed up in >> volume a bit >> over a decade ago. That one is packaged with a (noisy) switching power >> supply. >> >> There is no easy way to tell what era it is from. Indeed if it is from >> the 1990’s the >> OCXO will not be quite as good as what’s in one from > 2002. Since the >> unit normally >> operates locked, that’s not a real big deal. >> >> Since Trimble used “Thunderbolt” for a whole line of parts *and* was not >> very good >> at labeling devices, there is no easy way to refer to this or that >> specific device. That >> makes coming up with a list of units a bit hard. For example - what’s the >> model number >> of the part in that eBay listing ? ( No I don’t know either …. :) ). >> >> Bob >> >> > On Sep 12, 2020, at 12:28 PM, Adrian Godwin >> wrote: >> > >> > I've been looking for a thunderbolt for a while, mostly because they're >> > such a benchmark within this group. I missed the period when they were >> more >> > commonly available and have mostly found ones that were a lot more >> > expensive, or had a large delivery cost due to being in Australia. >> > >> > Some cheaper examples turned up on UK ebay. These aren't the classic >> > time-nuts ones but presumably look fairly similar to Lady Heather. >> > >> > https://www.ebay.co.uk/itm/154078750287 >> > >> > I haven't been able to find a comparison of the various thunderbolt >> models. >> > Is there a description somewhere ? I've found a few hints about this >> one - >> > I think it's a single 48V supply and possibly a lower-quality OCXO. >> > >> > On Sat, Sep 12, 2020 at 5:14 PM Kevin Schuchmann >> wrote: >> > >> >> Matthias, >> >>You are correct, having spent hours looking at all the stable areas >> >> and cooling and heating the gpsdo I find that when it reports that it >> is >> >> 116.25 F then it is stable. >> >> So now I guess I need to figure out why it is so picky. I will measure >> >> the current draw from a cold start and see if I see the oven warming up >> >> and then stabilizing and then heat and cool it and see how it reacts, >> >> and also look at the electronics and see if an area is overly sensitive >> >> to temperature. >> >> >> >> Thanks >> >> Kevin >> >> >> >> >> >> On 9/11/2020 2:26 AM, Matthias Welwarsky wrote: >> >>> On Freitag, 11. September 2020 01:08:09 CEST Kevin Schuchmann wrote: >> Guess my image didn't make it, I will add it as an attachment this >> time. >> >>> The temperature curve seems to show some correlation to what is >> >> happening with >> >>> the DAC. Seems that the DAC and OSC jumps are mostly during periods of >> >> some >> >>> thermal perturbation. >> >>> >> >>> Regards, >> >>> Matthias >> >>> >> >>> >> >>> >> >>> ___ >> >>> time-nuts mailing list -- time-nuts@lists.febo.com >> >>> To unsubscribe, go to >> >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> >>> and follow the instructions there. >> >> >> >> >> >> ___ >> >> time-nuts mailing list -- time-nuts@lists.febo.com >> >> To unsubscribe, go to >> >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> >> and follow the instructions there. >> >> >> > ___ >> > time-nuts mailing list -- time-nuts@lists.febo.com >> > To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> > and follow the instructions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.
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Re: [time-nuts] BVA 8600 Available for sale: Link to Dropbox photos/ADEV plot.
Hi James, I wonder, What reference did you use to measure the ADEV? Thanks! Jorge. On Tue, Sep 22, 2020 at 6:03 PM James Robbins wrote: > TN List: > > > > I am offering a fully operational Dual Output 5MHz 24v Oscilloquartz BVA > 8600 (sn:726) in excellent condition for sale to TimeNuts members before > offering it on EBAY. I have placed photos of the unit and an ADEV plot of > it done by Corby into a shared Dropbox folder for review. (See link > below.) > Price is $1500 plus insured shipping of $35. Unit has never been opened. > Selling to raise funds for another project. Note that a small hollow tube > has been epoxied to the case to facilitate screw driver insertion and > alignment for frequency trimming. I will include a connector for the DC > power. > > > > Jim Robbins, N1JR > > > > https://www.dropbox.com/sh/oqwa5rbcgb7xmy2/AAAxH4il6PNqx6re2pXQ3kRwa?dl=0 > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
