Re: [time-nuts] Are these PRS10's worth it ?
In message 54a20c7c.7040...@skybase.net, Tim writes: Not knowing much about the PRS10, I'm just wondering if its worth the ri$k :) You need to hold that price up against the fact that a new PRS10 is $1600. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
Re: [time-nuts] New GPSDO on EBAY From China
Hi Based on the dates I’ve seen on pictures and boards, this is a *very* new project. I suspect that what we are looking at is approximately beta test software. There’s likely to be a good part of a year or more spent optimizing the code. There’s no shame in any of that. It’s the nature of doing this kind of thing. You need working hardware to refine the software. To the points made earlier, the designer(s) have avoided many of the traps people fall into when doing this kind of thing. They are off to a good start. Where they end up will depend a lot on how many people are involved and what sort of gear they all have for measuring things. Could this be the final hardware? Maybe. Could they find a hardware issue when debugging the software? That stuff happens (to me). Could all our yelling about this turn them off to the idea and the whole project crashes and burns - I’ve seen that before as well. At this point we know little of the hardware design. Since we also know virtually noting about the internal Chinese market for parts, I doubt we could help much if we did see a bill of material. Some of this is simply a matter of trust in the designer. That’s not a bad thing. I’d much rather see a $75 design that works with parts they can get than a $800 design done with US parts. Hopefully we will find out more about this project as it moves forward. It’s only going to get better from here on. Does any of that change what I would recommend for a “one and only” GPSDO today? No. If it’s going to be your only standard, you want something that’s had the bugs worked out of it. The recommendation stands *not* because the Chinese GPSDO is in some way defective or a bad idea. It stands simply because you should play it safe on a single standard. - Right now there are several GPSDO’s on the market in the $150 to $250 (delivered) price range. That also is a good thing. You have multiple choices and there is no need for a “one size fits all” answer. Bob On Dec 29, 2014, at 2:07 PM, xaos x...@darksmile.net wrote: You have to give the guy credit for trying. What is a shame here is that he did not publish the schematics and the source code. If anyone knows him he should just ask him. We tend to be sceptics here but that's the nature of the game. However, I don't want anyone to think that we are elitist. I remember my first GPSDO, by Brooks Sherra, on QST. I remember reading the schematic and the source code many times until I got it. It is the reason I got interested in time-nuts to begin with. So, I think we would all benefit from going a bit deeper on this new unit. I hope the designer is reading this. GKH, N2FGX On 12/29/2014 12:50 AM, Charles Steinmetz wrote: Li Ang wrote: This unit is done by BG7TBL. In his store on taobao.com, there is a adev chart. Please refrer to this link That ADEV chart (see below) raises more questions than it answers. At least the time constant is not too short (a very common problem with DIY GPSDOs). But when the GPS takes over above the crossover (tau ~ 5000 seconds), the ADEV is ~2e-11. GPS should be significantly better than this at 5000 seconds. It appears that something is wrong with the design. Best regards, Charles ___ 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. ___ 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.
Re: [time-nuts] New GPSDO on EBAY From China
Hi One of my friend had one. Here is the test result from him. Bob Camp kb...@n1k.org于2014年12月29日星期一写道： Hi Ok, well that’s a move forward on this GPSDO. There is a *lot* more data on that listing than there was a month ago. Thanks for digging it up and posting the link. If you look at the ADEV at 1 second, it’s running at 2.67 x10^-11. That’s all coming from the Erratum Rb that they are using as a reference. At 100 seconds the Rb should be around 2.67 x10^-12 and the MV-89 should be about 2x10^-11. They combine as the square root, so that would be 3.3 ppt or less. The unit is running at 4.8 ppt so the filter is having some impact at that point. Out around 5,000 seconds the unit has a major hump. The Nortel GPSTM has a similar hump, but much closer in. It’s performance at 5K seconds is much better. The Lucent KS boxes beat this part across the entire range. That makes some assumptions, since there is no good ADEV data inside 100 seconds on the plot. The final question about the plot would be - what happens at longer tau? The run was stopped before it really got past the peak in the filter. It would be nice to see some data that at least gets back down to 1 ppt at the longer tau’s. Without that data it’s unclear how well the whole system is doing. That’s not to say it’s not doing well. It could be doing a great job, there’s just no way to know from the data. My guess is that this is very much like your counter project, just a bit further along. They have a nice looking unit, but are still trying to figure out the bugs and finish up the software … Bob On Dec 28, 2014, at 6:19 PM, Li Ang lll...@gmail.com wrote: Hi This unit is done by BG7TBL. In his store on taobao.com, there is a adev chart. Please refrer to this link http://item.taobao.com/item.htm?spm=a1z10.3.w4002-1278071728.49.XHJlQLid=42336500072 2014-12-29 1:56 GMT+08:00 Dan Rae dan...@verizon.net: On 12/28/2014 7:25 AM, David Smith wrote: Hello Friends, I found this new inexpensive GPSDO on ebay listed from a seller from China: Dave, these have been discussed in the past at some length on this list. I would point out that they use a re-cycled Morion OCXO. I have had two of these ovens from China; one worked fine, the other has a very high level of spurious outputs. I would be wary of using these in anything without first testing them thoroughly. Dan ___ 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. ___ 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.
Re: [time-nuts] Are these PRS10's worth it ?
Hi I had two PRS10 units that failed after one year of use. It was not just the lamp, also the RF section that excites the lamp had problems. I think it is too expensive... Regards, Vasco Soares - Original Message - From: Tim t...@skybase.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, December 30, 2014 2:22 AM Subject: [time-nuts] Are these PRS10's worth it ? Hi all, Been on the lookout for a PRS10 to build a GPSDO+RB arrangement and I see these... http://www.ebay.com/itm/Stanford-Research-Systems-SRS-PRS10-Rubidium-Freq-Standard-12344101-08-no-lock-/231435472155 Is this just a reheat-the-bulb fix or do you suspect something more ? Not knowing much about the PRS10, I'm just wondering if its worth the ri$k :) thanks Tim -- VK2XAX :: QF56if23 :: BMARC :: WIA :: AMSATVK ___ 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.
Re: [time-nuts] Are these PRS10's worth it ?
Check the difference between the LPRO and PRS-10 on John Miles' page: http://www.ke5fx.com/rb.htm Assuming these plots are representative of what you are likely to get from eBay parts (a pretty big assumption right there), the main advantage of the PRS-10 seems to be at high tau, where the performance of a GPSDRb is mostly driven by the GPS and PLL anyhow. Didier KO4BB On Tue, Dec 30, 2014 at 7:14 AM, Didier Juges shali...@gmail.com wrote: You can get a working LPRO for $150 with very reasonable shipping. To me, that's a better deal unless you absolutely need the thrill of trying to rescue something you knew was bad when you bought it :) http://www.ebay.com/itm/Datum-Efratom-Symmetricom-LPRO-10MHz-Rubidium-Oscillator-Tested-5-93-Lamp-Volts-/231436344277?pt=LH_DefaultDomain_0hash=item35e2ae5bd5 Didier KO4BB On Tue, Dec 30, 2014 at 3:15 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 54a20c7c.7040...@skybase.net, Tim writes: Not knowing much about the PRS10, I'm just wondering if its worth the ri$k :) You need to hold that price up against the fact that a new PRS10 is $1600. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
Re: [time-nuts] If your 5335A is acting goofy or dead...
Magnus, The service note is attached. Orin. On Sun, Dec 28, 2014 at 8:04 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: We had that issue with the 5335A at work, and replacing the relay did the trick. 5335A is still the counter which is easiest to use, even if it doesn't have stellar performance, but usually that is not needed. Where did you find the Service Note? Cheers, Magnus On 12/28/2014 06:06 AM, Orin Eman wrote: While evaluating my LTE Lite and testing my buffer board, my 5335A started acting goofy - random hangs/crashes etc.. This morning, the fan came on, but no display. To make a long story short, the problem was exactly as described in Service Note 5335A-26B. I found evidence of overheating on the power supply relay. The 5V (and 3V) supply was down. During investigating the fault, I disturbed the power supply relay and reseated it. The instrument worked again. Further investigation revealed a cold looking solder joint on the relay socket and spread contacts on the relay socket. About 1V was dropped across the relay socket and the relay itself. I resoldered the socket and 'persuaded' the contact with a small screwdriver. All now seems to be back to normal. FWIW, do not believe the part number on the relay. It is really a 6PST NO beastie for which I have not yet found a replacement. The above mentioned service note adds a second pair of contacts for the 5V supply after replacing the 120V fan with a 24V fan fed from the power switch. This uses the relay contacts that used to be used to drive the 120V fan. Ideally, you replace the relay and its socket as well, but good luck finding the relay. My unit has the 24V fan, but I have yet to do the rewiring for the second pair of contacts, so I suspect the fix might not last. Still, it's 22 years since the date on the service note, so I might have a few years. So, if your 5335A fan comes on, but no display, check the 5V supply first and if it's down, suspect the power supply relay/socket. Orin. ___ 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. Service Note 5335A-26B.pdf Description: Adobe PDF document ___ 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] Are these PRS10's worth it ?
My experience has been similar to Vasco's. Of three defective PRS-10s acquired for about $100 or less each, one had a bad MiniCircuits 400 MHz VCO module and was an easy fix. Another had a rubidium bulb issue that I traced to the driving FET. I managed to replace the FET, but the replacement's bias characteristics were somewhat different than its predecessor's, keeping the sensing circuits in an alarm mode. At the factory, bias adjustments are made in the software; but SRI does not provide access to this feature for customers. I tried removing and replacing the FET with still another, but messed-up the circuit board in the process. I wish now I had tried to alter the FET bias by adding external series or shunt resistors. The third unit has an intermittent condition that causes it to be slow to lock at times and fine at others. I have spent hours trying to trace this, but so far without success. If you decide to take a chance on these units, I would not be inclined to offer more than $100 as their repair is a crap-shoot. I suspect many of the units offered for sale on eBay have been removed from Symmetricom TS-2500 and TS-2700 telephone industry timing sources. PRS-10s from these seem to have Customer Number 123-44101-4 on the label. I have also encountered PRS-10s with the Customer Numbers 123-44101-08 and -10 on the label and assume these were from other Symmetricom instruments. By the way, The TS-2500 is a GPS-referenced source; however, the unit seems to compare its internal crystal oscillator with GPS, the PRS-10, and other 10 MHz sources (that can be connected for monitoring) and keeps track of their behaviors with a microprocessor. It appears the PRS-10 is not locked to GPS, but is simply monitored and kept in reserve as a replacement frequency and timing source should GPS service fail. If the PRS-10 frequency wanders out of the acceptable range, the TS-2500 shows a fault signal, but does not attempt to adjust the PRS-10. Apparently the PRS-10's frequency is set at the Symmetricom factory and the unit is on its own after that. It is included in the TS-2500 box as baggage to be used only if the GPS timing fails. As it is kind of expensive to burn an SRI PRS-10 simply as a standby, although this provision is understandably important to telephone companies, an unmodified TS-2500 is of questionable utility to hobbyists. Bruce, KG6OJI ___ 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] HP-58503A
This list was recommended to me by the elecraft list. I have an HP-58503A sat disciplined “clock” that puts out a steady 10MHz to my K3 radio. Its been working 24/7 for years, I monitor it with David Anderson's Mac GPS Control X software on my iMac. Several days ago error messages showed up i.e.: Health- err, Self Test-err, Int Power- OK, OCXO- OK, EFC-OK GPS RCV-err. Its not tracking any sats and now I cannot event communicate with it at all even with a simple com program. Is there anyone out therE who can fix these things? Any suggestions would be appreciated. Thank you. Richard Thorpe K6CG ___ 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.
Re: [time-nuts] New GPSDO on EBAY From China
Hi On Dec 29, 2014, at 8:51 PM, Li Ang lll...@gmail.com wrote: Hi One of my friend had one. Here is the test result from him. Ok, that data is actually more encouraging than the data on the selling site. He ran it long enough to get past the hump in the ADEV curve at 4,000 seconds. The blue trace shows that the test setup *can* resolve the data properly. So now the question becomes - what is going on with the filter software in the BG7TBL unit? It’s obviously done differently than the HP filter software. There are a number of people (not me) on the list that have expressed interest in digging into GPSDO firmware. Bob Bob Camp kb...@n1k.org于2014年12月29日星期一写道： Hi Ok, well that’s a move forward on this GPSDO. There is a *lot* more data on that listing than there was a month ago. Thanks for digging it up and posting the link. If you look at the ADEV at 1 second, it’s running at 2.67 x10^-11. That’s all coming from the Erratum Rb that they are using as a reference. At 100 seconds the Rb should be around 2.67 x10^-12 and the MV-89 should be about 2x10^-11. They combine as the square root, so that would be 3.3 ppt or less. The unit is running at 4.8 ppt so the filter is having some impact at that point. Out around 5,000 seconds the unit has a major hump. The Nortel GPSTM has a similar hump, but much closer in. It’s performance at 5K seconds is much better. The Lucent KS boxes beat this part across the entire range. That makes some assumptions, since there is no good ADEV data inside 100 seconds on the plot. The final question about the plot would be - what happens at longer tau? The run was stopped before it really got past the peak in the filter. It would be nice to see some data that at least gets back down to 1 ppt at the longer tau’s. Without that data it’s unclear how well the whole system is doing. That’s not to say it’s not doing well. It could be doing a great job, there’s just no way to know from the data. My guess is that this is very much like your counter project, just a bit further along. They have a nice looking unit, but are still trying to figure out the bugs and finish up the software … Bob On Dec 28, 2014, at 6:19 PM, Li Ang lll...@gmail.com wrote: Hi This unit is done by BG7TBL. In his store on taobao.com, there is a adev chart. Please refrer to this link http://item.taobao.com/item.htm?spm=a1z10.3.w4002-1278071728.49.XHJlQLid=42336500072 2014-12-29 1:56 GMT+08:00 Dan Rae dan...@verizon.net: On 12/28/2014 7:25 AM, David Smith wrote: Hello Friends, I found this new inexpensive GPSDO on ebay listed from a seller from China: Dave, these have been discussed in the past at some length on this list. I would point out that they use a re-cycled Morion OCXO. I have had two of these ovens from China; one worked fine, the other has a very high level of spurious outputs. I would be wary of using these in anything without first testing them thoroughly. Dan ___ 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. ___ 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. 86068848562b6ac3c8c48d76d.jpg___ 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.
Re: [time-nuts] Lucent KS-24361 power connector
I have seen D connectors with the these lock type fittings before but never did know their correct name. I tried a variety of Google searches but never did find what I was looking for. I just never looked for D connector slide latches or slide locks. Because I didn't have the correct fittings and couldn't find them, I tried simply substituting with the more common screw type as you find on your typical desktop computer. I have them all changed out on my units now cheers, Graham On 2014-12-29 19:14, Martin A Flynn wrote: I am making up cables with slide latches for the Lucent KS-24361. Questions: * Are pins (Pin3 - Pin 9) in the P1 / DE-9 power connector assigned, or spare? * Has anyone determined the pin out for J3 / DE-9 alarm connector? Martin Flynn ___ 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.
Re: [time-nuts] Are these PRS10's worth it ?
$219 for a bad RB seems to be silly. Sorry I am not that much of a gambler. Regards Paul WB8TSL On Tue, Dec 30, 2014 at 8:17 AM, Didier Juges shali...@gmail.com wrote: Check the difference between the LPRO and PRS-10 on John Miles' page: http://www.ke5fx.com/rb.htm Assuming these plots are representative of what you are likely to get from eBay parts (a pretty big assumption right there), the main advantage of the PRS-10 seems to be at high tau, where the performance of a GPSDRb is mostly driven by the GPS and PLL anyhow. Didier KO4BB On Tue, Dec 30, 2014 at 7:14 AM, Didier Juges shali...@gmail.com wrote: You can get a working LPRO for $150 with very reasonable shipping. To me, that's a better deal unless you absolutely need the thrill of trying to rescue something you knew was bad when you bought it :) http://www.ebay.com/itm/Datum-Efratom-Symmetricom-LPRO-10MHz-Rubidium-Oscillator-Tested-5-93-Lamp-Volts-/231436344277?pt=LH_DefaultDomain_0hash=item35e2ae5bd5 Didier KO4BB On Tue, Dec 30, 2014 at 3:15 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message 54a20c7c.7040...@skybase.net, Tim writes: Not knowing much about the PRS10, I'm just wondering if its worth the ri$k :) You need to hold that price up against the fact that a new PRS10 is $1600. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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. ___ 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.
Re: [time-nuts] New GPSDO on EBAY From China
Thanks for the discussion on this GPSDO. I researched the archives on this going back a few months but didn't find anything. Although I consider myself a newby or novice Time-Nut I do have three other GPSDO's I've had a Z3801 running for more than 10 years. My interest in the unit in question lies in the need for a light weight unit I can use as a stable accurate source for my 24 GHz transverter that I use for my rover and contesting efforts. I need something light weight as well as accurate and stable with low phase noise and needs to be able to be located on or close to a portable tripod. I did order one of James Millers units to fulfill these needs. I just thought this may be a much less expensive alternative. Thanks again for the discussion. Happy New Year to all! Dave - W6TE From: kb...@n1k.org Date: Tue, 30 Dec 2014 09:33:06 -0500 To: time-nuts@febo.com Subject: Re: [time-nuts] New GPSDO on EBAY From China Hi On Dec 29, 2014, at 8:51 PM, Li Ang lll...@gmail.com wrote: Hi One of my friend had one. Here is the test result from him. Ok, that data is actually more encouraging than the data on the selling site. He ran it long enough to get past the hump in the ADEV curve at 4,000 seconds. The blue trace shows that the test setup *can* resolve the data properly. So now the question becomes - what is going on with the filter software in the BG7TBL unit? It’s obviously done differently than the HP filter software. There are a number of people (not me) on the list that have expressed interest in digging into GPSDO firmware. Bob Bob Camp kb...@n1k.org于2014年12月29日星期一写道： Hi Ok, well that’s a move forward on this GPSDO. There is a *lot* more data on that listing than there was a month ago. Thanks for digging it up and posting the link. If you look at the ADEV at 1 second, it’s running at 2.67 x10^-11. That’s all coming from the Erratum Rb that they are using as a reference. At 100 seconds the Rb should be around 2.67 x10^-12 and the MV-89 should be about 2x10^-11. They combine as the square root, so that would be 3.3 ppt or less. The unit is running at 4.8 ppt so the filter is having some impact at that point. Out around 5,000 seconds the unit has a major hump. The Nortel GPSTM has a similar hump, but much closer in. It’s performance at 5K seconds is much better. The Lucent KS boxes beat this part across the entire range. That makes some assumptions, since there is no good ADEV data inside 100 seconds on the plot. The final question about the plot would be - what happens at longer tau? The run was stopped before it really got past the peak in the filter. It would be nice to see some data that at least gets back down to 1 ppt at the longer tau’s. Without that data it’s unclear how well the whole system is doing. That’s not to say it’s not doing well. It could be doing a great job, there’s just no way to know from the data. My guess is that this is very much like your counter project, just a bit further along. They have a nice looking unit, but are still trying to figure out the bugs and finish up the software … Bob On Dec 28, 2014, at 6:19 PM, Li Ang lll...@gmail.com wrote: Hi This unit is done by BG7TBL. In his store on taobao.com, there is a adev chart. Please refrer to this link http://item.taobao.com/item.htm?spm=a1z10.3.w4002-1278071728.49.XHJlQLid=42336500072 2014-12-29 1:56 GMT+08:00 Dan Rae dan...@verizon.net: On 12/28/2014 7:25 AM, David Smith wrote: Hello Friends, I found this new inexpensive GPSDO on ebay listed from a seller from China: Dave, these have been discussed in the past at some length on this list. I would point out that they use a re-cycled Morion OCXO. I have had two of these ovens from China; one worked fine, the other has a very high level of spurious outputs. I would be wary of using these in anything without first testing them thoroughly. Dan ___ 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. ___ 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. 86068848562b6ac3c8c48d76d.jpg___ 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.
Re: [time-nuts] Are these PRS10's worth it ?
Hi If indeed these PRS-10’s are out of TS boxes (and that’s a real good guess) there is one other thing to consider: Not all PRS-10’s are created equal. Some have fancy disciplining firmware in them. Some have better temperature specs. Some have better ADEV specs. Some (may) have longer running life specs. There also is a “good phase noise” version. When you look at PRS-10 plots, you need to ask “is this the version I have …”. For what ever reason, the ones out of the TS boxes are not the best of the bunch. I’d bet they simply put in the options they needed and cost reduced the other stuff out. The variation in PRS-10’s is not quite as crazy as on the FEI Rb’s. They all have the same basic outputs and at least respond to basic commands. Bob On Dec 30, 2014, at 1:00 PM, Bruce Hunter via time-nuts time-nuts@febo.com wrote: My experience has been similar to Vasco's. Of three defective PRS-10s acquired for about $100 or less each, one had a bad MiniCircuits 400 MHz VCO module and was an easy fix. Another had a rubidium bulb issue that I traced to the driving FET. I managed to replace the FET, but the replacement's bias characteristics were somewhat different than its predecessor's, keeping the sensing circuits in an alarm mode. At the factory, bias adjustments are made in the software; but SRI does not provide access to this feature for customers. I tried removing and replacing the FET with still another, but messed-up the circuit board in the process. I wish now I had tried to alter the FET bias by adding external series or shunt resistors. The third unit has an intermittent condition that causes it to be slow to lock at times and fine at others. I have spent hours trying to trace this, but so far without success. If you decide to take a chance on these units, I would not be inclined to offer more than $100 as their repair is a crap-shoot. I suspect many of the units offered for sale on eBay have been removed from Symmetricom TS-2500 and TS-2700 telephone industry timing sources. PRS-10s from these seem to have Customer Number 123-44101-4 on the label. I have also encountered PRS-10s with the Customer Numbers 123-44101-08 and -10 on the label and assume these were from other Symmetricom instruments. By the way, The TS-2500 is a GPS-referenced source; however, the unit seems to compare its internal crystal oscillator with GPS, the PRS-10, and other 10 MHz sources (that can be connected for monitoring) and keeps track of their behaviors with a microprocessor. It appears the PRS-10 is not locked to GPS, but is simply monitored and kept in reserve as a replacement frequency and timing source should GPS service fail. If the PRS-10 frequency wanders out of the acceptable range, the TS-2500 shows a fault signal, but does not attempt to adjust the PRS-10. Apparently the PRS-10's frequency is set at the Symmetricom factory and the unit is on its own after that. It is included in the TS-2500 box as baggage to be used only if the GPS timing fails. As it is kind of expensive to burn an SRI PRS-10 simply as a standby, although this provision is understandably important to telephone companies, an unmodified TS-2500 is of questionable utility to hobbyists. Bruce, KG6OJI ___ 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.
Re: [time-nuts] Are these PRS10's worth it ?
Hi There is a lot of *stuff* in an Rb beyond just the lamp. It *could* be as simple as a VCXO centering adjustment. It also could be an alignment adjustment. I don’t believe there are any schematics out there on these devices, so it’s a “trace it out and see” sort of fix. Even with the schematic, if it’s an alignment (peak this / dip that / back off 1/8th turn) process there are no documents on any of the Rb’s for that stuff. If you want a science project, something like an FRK probably has easier access to the insides. There also are more people who have poked around in them. Personally I’d just wait for the next flood of $60 +/- $25 working parts to hit the market and stock up then. You are likely looking at getting two or three of the non-working parts to come up with one working one. That sort of money will buy a pretty good pile of the others. Bob On Dec 29, 2014, at 9:22 PM, Tim t...@skybase.net wrote: Hi all, Been on the lookout for a PRS10 to build a GPSDO+RB arrangement and I see these... http://www.ebay.com/itm/Stanford-Research-Systems-SRS-PRS10-Rubidium-Freq-Standard-12344101-08-no-lock-/231435472155 Is this just a reheat-the-bulb fix or do you suspect something more ? Not knowing much about the PRS10, I'm just wondering if its worth the ri$k :) thanks Tim -- VK2XAX :: QF56if23 :: BMARC :: WIA :: AMSATVK ___ 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.
Re: [time-nuts] Are these PRS10's worth it ?
Bruce wrote: By the way, The TS-2500 is a GPS-referenced source; however, the unit seems to compare its internal crystal oscillator with GPS, the PRS-10, and other 10 MHz sources (that can be connected for monitoring) and keeps track of their behaviors with a microprocessor. It appears the PRS-10 is not locked to GPS, but is simply monitored and kept in reserve as a replacement frequency and timing source should GPS service fail. If the PRS-10 frequency wanders out of the acceptable range, the TS-2500 shows a fault signal, but does not attempt to adjust the PRS-10. Apparently the PRS-10's frequency is set at the Symmetricom factory and the unit is on its own after that. I have played with several TS-2700s (which are disciplined by CDMA cell transmitters rather than GPS), and they work the same way. They track all of the timing data they are given, and output the best fit 10MHz they can calculate using their BesTime engines. The TS-2700 keeps a running log of its estimate of the PRS10 frequency but, as you say, it does not adjust the PRS10. It is included in the TS-2500 box as baggage to be used only if the GPS timing fails. As it is kind of expensive to burn an SRI PRS-10 simply as a standby I'm not sure the TS-2700 (and, by implication, perhaps the 2500) ever just outputs the raw PRS10 frequency. I think it always outputs a frequency calculated from the various timing inputs. If it loses the CDMA signal and falls back to the PRS10, I think it uses the stored offset for the PRS10 to generate the output frequency. The manual says, If the CDMA signals are disrupted, the BesTime algorithm continues to predict CDMA timing information, which enhances system holdover performance. I don't know if it uses the last-known offset, or tries to project a current offset based on the trend line. Best regards, Charles ___ 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.
Re: [time-nuts] Lucent KS-24361 power connector
This appears to be a compatible part for the DE sized connectors: http://www.newark.com/harting/09-67-000-9914/slide-lock-de/dp/93C7911 Search through the technical data sheet for 9914 and you'll see it listed for 9 pin connectors. Of course, these may be completely wrong so do your homework and don't take my word for it. -Bob On Tue, Dec 30, 2014 at 7:51 AM, Graham planoph...@aei.ca wrote: I have seen D connectors with the these lock type fittings before but never did know their correct name. I tried a variety of Google searches but never did find what I was looking for. I just never looked for D connector slide latches or slide locks. Because I didn't have the correct fittings and couldn't find them, I tried simply substituting with the more common screw type as you find on your typical desktop computer. I have them all changed out on my units now cheers, Graham On 2014-12-29 19:14, Martin A Flynn wrote: I am making up cables with slide latches for the Lucent KS-24361. Questions: * Are pins (Pin3 - Pin 9) in the P1 / DE-9 power connector assigned, or spare? * Has anyone determined the pin out for J3 / DE-9 alarm connector? Martin Flynn ___ 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. ___ 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.
