Re: [time-nuts] future NTP programs...
In message 54615794.3040...@rubidium.dyndns.org, Magnus Danielson writes: I'm just saying that the NTP processing and the NTP monitoring may not need to run by the same daemon necessarily. As the Varnish architecture shows, I'm fully in agreement with this. I should also add that one of the reasons I don't like the control mode packets is that they are complex. I have no issues with handling the standard 48 byte fixed format, no strings NTP timing packets in a root-process, but in todays environment it would not be OK to design a daemon which handles the crypto stuff or the control packets in a root-process, those should go in a sandbox. -- 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] future NTP programs...
it would not be OK to design a daemon which handles the crypto stuff or the control packets in a root-process, those should go in a sandbox. Absolutely agree, in my previous life in the data security arena (crypto, data security, white hat tester etc..), doing that sort of thing in a privileged process or similar (e.g. kernel) was a seriously discouraged - far too great a risk of compromise. Keep it all in a user state process with NO write access to anything except the communications port (serial / UDP / TCP / w.h.y.) it is talking on. Regards, David Partridge ___ 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] 10 MHz OCXO recommendations
Joe It is not clear to me what your goal is. Simplicity, cost or performance. A PLL based on 1 pps is not optimum. I call this approach GPSPLL versus GPSDO. Thanks to work done by Karen in Moscow I found out that you can program a $14 ublox M7 to frequencies above 1 KHz. If you use 200 KHz for 5 MHz XO and 400 KHz for 10 MHz you can make a GPS PLL with one 390, one 86 and an op amp. If the XO output is sine wave you have to add a Schmitt Trigger. I recommend Wenzel, AC14 or SN75176. I prefer 75176 it is 8 pin DIL. I do have a board layout if interested. Our Australian team members will introduce it to the HAM community. Not exactly a time nut product. We have done a GPSPLL using a M7 at 1 KHz and tests show better than 1 E-10 at 1 second after 10 seconds GPS takes over it gets better following GPS performance. I have a few boards and op amps left over if interested contact me off list. Bert Kehren In a message dated 11/11/2014 1:05:49 A.M. Eastern Standard Time, jg...@zianet.com writes: You can run at 400 KHz by dividing by 5/5 and 4/9. True. Either will work. You said 0.2ppm stability. What do you need for accuracy and/or how are you going to calibrate your setup? I will initially calibrate the OXCO against my HP GPSDO. Idealy, it will only need checking against the GPSDO once a year. Is that asking too much for it to be stable over that length of time? I could simply look up the specs for the various models that I find on ebay. However, I know that a lot of the stuff that is sold has been through the mill and may not meet spec any more. Thus my request for recommendations for models that someone here has actually purchased and tested. Joe Gray W5JG ___ 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] 10 MHz OCXO recommendations
Hi Ok, let’s back off a bit. If 0.2 ppm over a narrow range is the objective, that sounds like a TCXO application. If you really are only after the 14.4 MHz, that’s the quick / easy way to go. Everything running on 3.3V, total current may be below 10 ma. Far fewer parts involved. A lot depends on just how that spec gets interpreted. Surplus OCXO’s are well … surplus. A significant percentage of the OCXO’s I’ve seen on the surplus marked are pulls off boards and are busted. I’ve bought quite a few from “tested / guaranteed / 100% good / perfect buy” sellers and found issues with then when you carefully test them. My conclusion is that in most cases, tested = has some sort of output. Tested may not include “does not catch fire if left on for an hour”. I’ve bought them from the same people everybody else has. There are a couple ways around this. The first is to buy parts that have never been on boards. You can be pretty sure that a part with long leads has not been on a board. Finding OCXO’s at 10 MHz that way is not very easy. The next approach is to buy a working device (like a GPSDO or test gear) and pull it’s OCXO. This works much better if you bought the thing 15 years ago and its not been of any use. You could buy parts brand new, you then run into the fact (been true forever) that surplus is pennies on the dollar. The final solution is the most common - buy lots of OCXO’s and sort them out / repair them yourself. If you are going the sort / repair route, the Morion MV-89 parts are out there in bulk and are pretty cheap. There are no published schematics, so it’s a trace it out and debug thing to fix one. You also need to be a bit handy with something like a torch to get them open. The trick is to do it in a way you can re-seal the parts. The “Trimble” OCXO’s are not quite as common. Welded package parts are going to be a sort only thing, Popping them open and then re-welding them - not so much. That Jackson Labs GPSDO on eBay is sounding better and better isn’t it? Bob On Nov 11, 2014, at 1:05 AM, Joseph Gray jg...@zianet.com wrote: You can run at 400 KHz by dividing by 5/5 and 4/9. True. Either will work. You said 0.2ppm stability. What do you need for accuracy and/or how are you going to calibrate your setup? I will initially calibrate the OXCO against my HP GPSDO. Idealy, it will only need checking against the GPSDO once a year. Is that asking too much for it to be stable over that length of time? I could simply look up the specs for the various models that I find on ebay. However, I know that a lot of the stuff that is sold has been through the mill and may not meet spec any more. Thus my request for recommendations for models that someone here has actually purchased and tested. Joe Gray W5JG ___ 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] 10 MHz OCXO recommendations
If 0.2 ppm over a narrow range is the objective, that sounds like a TCXO application. Please point me to such a TCXO at 14.4 MHz that is affordable. Joe Gray W5JG ___ 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] Electrolytic Capacitor Question
The Ta caps in old HP gear should last virtually forever, especially if they have already lasted for decades. What you are referring to as wet slug Ta caps are mostly dry solid ones in hermetically sealed cans. There can be some actual wet slug types, but only in certain spots where their unique characteristics are necessary. These can often be identified by the end seals - they are not hermetic, but elastomer sealed with rubbery material, and the anode lead is a solid Ta wire that's butt-welded to a steel wire that's solderable. You can see the weld where it goes from the bluish or brownish Ta color to the tinned lead, except in types that put a glob of epoxy over the end. As I recall, a lot of the ones used by HP are marked 109D type after the original Sprague (or Mallory?) product line. The dry types have a true hermetic glass to steel seal that's soldered to the can and the anode lead, which is steel or copper alloy all the way. This is the best kind of electrolytic cap for lifetime and durability, in my opinion. The wet slug ones can leak after many years, and the sulfuric acid electrolyte can damage things nearby. Whether they can be replaced readily depends on the application. Wet slug types have the lowest DC current leakage and highest temperature range of all electrolytic caps, very low ESR, and wide voltage range. If it's a low-leakage circuit requirement, and fairly low C (like up to a few tens of uF), the best bet may be to use plastic caps, even several paralleled to get the right amount - but the physical size will be much larger. For larger values, this is impractical, so the next closest thing is dry Ta caps, with more leakage, but may be OK for bench use at room temperature. One very common use in HP gear is to have a wet Ta switched across a YTO coil whenever the oscillator is in CW or narrowband mode, for extra noise filtering. Any DC leakage would cause errors in the tuning current. Don't use regular Al or OSCON caps for low leakage circuits. Ed ___ 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] Si5351A
Some of you have probably already heard of this new clock generator chip from Si. News of a board with this chip from Adafruit just came up on a local Amateur list today. A quick Google shows that some folks have used this chip in homebrew SSB rigs. My concern would be that when this chip generated frequencies that required non-integer PLL ratios, that the jitter would be unacceptable for SSB use, and even worse for CW. As for the Adafruit board, they are using a crystal spec'ed for 30ppm accuracy and stability. Not something I'd want to use in a radio. Perhaps the C version of the chip, fed by a TCXO. What do you think about the jitter issue? Joe Gray W5JG ___ 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] GSM/GPRS module timing accuracy
How accurately can you set, and keep in sync a local clock (in the UK) by getting timing from a cellular network using a very low cost GSM/GPRS modem module such as a SIM900? Is it possible to get better than hundreds of microseconds for example, perhaps even a few tens of us? How frequently can the clock be synced (to avoid having to have a high performance local clock) and would it incur network charges? Does it depend mostly on the network, the module, location or the algorithms employed? I am thinking of a fixed location application but presumably couldn't guarantee that connections will always be to the same base station so is it possible to estimate the distance to the base station to compensate for the time of flight of the radio signal? I guess it should be possible to read the signal strength from the radio module to get a crude estimate. It should be obvious that I know next to nothing about GSM standards other than that the base stations have access to a high quality clock. If its not possible to do this reliably, are their any low cost ( $20) combined GSM/GPRS + GPS modules which provide timing accurate to a few 10s of us or so? Thanks Tony H ___ 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] 10 MHz OCXO recommendations
Hi I have not had much luck with ocxo's sourced from the usual auction site. By far and away the best value for money for me has been found in some packaged frequency standards containing OCXO's and a non auction site purchase of a BVA OCXO. I find the concept of occasionally adjusting a good OCXO which in turn is used as a reference works well for me.I have some that haven't needed adjustment for over 2 years (they are still well within one part per billion of being on frequency.) That being said the MV89's were at least fairly in expensive. Mark Spencer On 2014-11-10, at 10:05 PM, Joseph Gray jg...@zianet.com wrote: You can run at 400 KHz by dividing by 5/5 and 4/9. True. Either will work. You said 0.2ppm stability. What do you need for accuracy and/or how are you going to calibrate your setup? I will initially calibrate the OXCO against my HP GPSDO. Idealy, it will only need checking against the GPSDO once a year. Is that asking too much for it to be stable over that length of time? I could simply look up the specs for the various models that I find on ebay. However, I know that a lot of the stuff that is sold has been through the mill and may not meet spec any more. Thus my request for recommendations for models that someone here has actually purchased and tested. Joe Gray W5JG ___ 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] 10 MHz OCXO recommendations
Connor-Winfield has a line of TCXO's with 0.1 ppm stability that can be bought from Digi-Key in single unit quantities for about $25. Search for M100F. They don't have a 14.4 Mhz, but they do have 10.0 Mhz, which you indicated could also work for you. Regards, John AC0ZG On 11/11/2014 11:20 AM, Joseph Gray wrote: If 0.2 ppm over a narrow range is the objective, that sounds like a TCXO application. Please point me to such a TCXO at 14.4 MHz that is affordable. Joe Gray W5JG ___ 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] GSM/GPRS module timing accuracy
How are you getting time from the GSM network? If you are using the NITZ (look it up) service then you can use an unactivated SIM for free, but the accuracy is woeful, it can be seconds out. Else you will have to have a live SIM and use NTP to a server. If you make any progress please post to the list. I have not heard of being able to access the clock in the tower over the network. The beauty of phone network is that it works in buildings, where GPS does not reach. Tom Harris celephi...@gmail.com On 12 November 2014 01:24, Tony tn...@toneh.demon.co.uk wrote: How accurately can you set, and keep in sync a local clock (in the UK) by getting timing from a cellular network using a very low cost GSM/GPRS modem module such as a SIM900? Is it possible to get better than hundreds of microseconds for example, perhaps even a few tens of us? How frequently can the clock be synced (to avoid having to have a high performance local clock) and would it incur network charges? Does it depend mostly on the network, the module, location or the algorithms employed? I am thinking of a fixed location application but presumably couldn't guarantee that connections will always be to the same base station so is it possible to estimate the distance to the base station to compensate for the time of flight of the radio signal? I guess it should be possible to read the signal strength from the radio module to get a crude estimate. It should be obvious that I know next to nothing about GSM standards other than that the base stations have access to a high quality clock. If its not possible to do this reliably, are their any low cost ( $20) combined GSM/GPRS + GPS modules which provide timing accurate to a few 10s of us or so? Thanks Tony H ___ 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] Si5351A
The specs for period, cycle-to-cycle and phase jitter are on page 6 of the data sheet, which is here: http://www.adafruit.com/datasheets/Si5351.pdf Wayne On Tue, Nov 11, 2014 at 12:49 PM, Joseph Gray jg...@zianet.com wrote: Some of you have probably already heard of this new clock generator chip from Si. News of a board with this chip from Adafruit just came up on a local Amateur list today. A quick Google shows that some folks have used this chip in homebrew SSB rigs. My concern would be that when this chip generated frequencies that required non-integer PLL ratios, that the jitter would be unacceptable for SSB use, and even worse for CW. As for the Adafruit board, they are using a crystal spec'ed for 30ppm accuracy and stability. Not something I'd want to use in a radio. Perhaps the C version of the chip, fed by a TCXO. What do you think about the jitter issue? Joe Gray W5JG ___ 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] GSM/GPRS module timing accuracy
On 11/11/2014 21:52, Tom Harris wrote: How are you getting time from the GSM network? If you are using the NITZ (look it up) service then you can use an unactivated SIM for free, but the accuracy is woeful, it can be seconds out. I'm not at the moment; mobile phones do set their clocks from the network but I've no idea how accurately it can be done - which is why I was asking. Else you will have to have a live SIM and use NTP to a server. If you make any progress please post to the list. I have not heard of being able to access the clock in the tower over the network. The beauty of phone network is that it works in buildings, where GPS does not reach. Tom Harris celephi...@gmail.com I would have a live SIM as the modem would be used periodically (but not necessarily frequently - perhaps every 24 hours or more) to send data. I would not want to use an NTP service as I would only have a micro-controller with limited memory. Tony H ___ 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] 10 MHz OCXO recommendations
Hi This is one of several that come up when I do a search at Mouser: http://www.mouser.com/ProductDetail/ABRACON/ASVTX11-14400MHZ-T/?qs=sGAEpiMZZMsBj6bBr9Q9aTQ72VsxIq1y8x3GpFIJ334%3d That’s the link, to the full reel. At one piece they are $5.89 each. Temperature spec is +/- 2.5 ppm over -30 to +75C. Runs off of 3.3V at low current. Many of these parts are compensated to be pretty flat past room temperature. If it was a straight line (which it most certainly is not) you might get 0.25 ppm over 10C. If you are after a normal room environment, it’ll swing 2 to 4C. Bob On Nov 11, 2014, at 1:20 PM, Joseph Gray jg...@zianet.com wrote: If 0.2 ppm over a narrow range is the objective, that sounds like a TCXO application. Please point me to such a TCXO at 14.4 MHz that is affordable. Joe Gray W5JG ___ 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] Si5351A
Hi When you look at the parts some people use in radios, this one is better than some of them. No, it’s not what I would use. Bob On Nov 11, 2014, at 3:49 PM, Joseph Gray jg...@zianet.com wrote: Some of you have probably already heard of this new clock generator chip from Si. News of a board with this chip from Adafruit just came up on a local Amateur list today. A quick Google shows that some folks have used this chip in homebrew SSB rigs. My concern would be that when this chip generated frequencies that required non-integer PLL ratios, that the jitter would be unacceptable for SSB use, and even worse for CW. As for the Adafruit board, they are using a crystal spec'ed for 30ppm accuracy and stability. Not something I'd want to use in a radio. Perhaps the C version of the chip, fed by a TCXO. What do you think about the jitter issue? Joe Gray W5JG ___ 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] Si5351A
John Miles did the phase noise measurments, they are avaible here: http://nt7s.com/2014/11/si5351a-investigations-part-7/ BR Thomas. 2014-11-11 21:49 GMT+01:00 Joseph Gray jg...@zianet.com: Some of you have probably already heard of this new clock generator chip from Si. News of a board with this chip from Adafruit just came up on a local Amateur list today. A quick Google shows that some folks have used this chip in homebrew SSB rigs. My concern would be that when this chip generated frequencies that required non-integer PLL ratios, that the jitter would be unacceptable for SSB use, and even worse for CW. As for the Adafruit board, they are using a crystal spec'ed for 30ppm accuracy and stability. Not something I'd want to use in a radio. Perhaps the C version of the chip, fed by a TCXO. What do you think about the jitter issue? Joe Gray W5JG ___ 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. -- Please avoid sending me Word or PowerPoint attachments. See http://www.gnu.org/philosophy/no-word-attachments.html PDF is an better alternative and there are always LaTeX! ___ 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] GSM/GPRS module timing accuracy
I am in Australia and the accuracy of the NITZ service can be slow by up to 15 SECONDS. I have no idea why it is so bad. You can try this for yourself. Just get a GSM modem connected to your laptop, set it up to accept NITZ updates and print the results on the serial port, and take a drive around your neighbourhood. As you go between towers you will get new NITZ updates, and you can log the accuracy. Try not to get arrested as a terrorist :) There is a simplified NTP service that only receives a small packet, I think I saw an example for Arduino. Tom Harris celephi...@gmail.com On 12 November 2014 09:34, Tony tn...@toneh.demon.co.uk wrote: On 11/11/2014 21:52, Tom Harris wrote: How are you getting time from the GSM network? If you are using the NITZ (look it up) service then you can use an unactivated SIM for free, but the accuracy is woeful, it can be seconds out. I'm not at the moment; mobile phones do set their clocks from the network but I've no idea how accurately it can be done - which is why I was asking. Else you will have to have a live SIM and use NTP to a server. If you make any progress please post to the list. I have not heard of being able to access the clock in the tower over the network. The beauty of phone network is that it works in buildings, where GPS does not reach. Tom Harris celephi...@gmail.com I would have a live SIM as the modem would be used periodically (but not necessarily frequently - perhaps every 24 hours or more) to send data. I would not want to use an NTP service as I would only have a micro-controller with limited memory. Tony H ___ 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] My NTGS50AA failed
Hello, After 2 yeses of continuous operation my NTGS50AA turned its red led on and stopped working. A check with LH shows OSC: BAD and OSC age alarm assuming that the oscillator had aged too much. I didn't believe this because when working, the DAC control voltage was around 2.9 V, in fact near the middle of its range (0-5 V). Measuring the 10 MHz output it is high, about 4.46 Hz which agrees with the LH figures. I measured the oscillator EFC pin and it is struck at 5.02 V, not following the DAC voltages as reported by LH. I think that either the DAC is bad or an amplifier after it. Since I don't have any schematic and the oscillator covers the top layer the troubleshooting is difficult. Has anybody experienced this failure before?. Does anybody has an schematic, even a partial one? Since the unit now is operating open loop I observed the locking strategy of this GPSDO. First it waits about 12 minutes for warming (I don't know if it internally monitors the oven current or uses a fixed time). During this period it sets the DAC output to the initial value as stored in the EEPROM (3.0 V). When it thinks that it is warmed enough, the DAC is ramped in the right direction to intercept exactly 10 MHz (towards 0 in my case). If it reaches 0 then declares the alarm and the DAC voltage is set to half the initial value (1.5 V). Five minutes later it switch the DAC to 2,25 V and 17 seconds later it returns to 1.5 V and remains there for 4 min and a half. Then it goes up again to 2.5 V and after 10 seconds it goes down to 1.88 V and after some 14 minutes it goes down again to 1.5 V, it remains there for about 15 minutes and then it goes down to 1.14 V, remains there for 80 seconds and goes back to 2.5 V. It looks like it checks from time to time if it is able to control the oscillator or simply it does weird things once it thinks that the oscillator cannot be disciplined. I will appreciate very much any information.that can help my troubleshooting. These units has more than doubled its price since I bought mine and I think that they are vanishing. The Guatemala's cell towers scrap has been exhausted. Regards, Ignacio EB4APL ___ 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] My NTGS50AA failed
Hi Ok, the gizmo you have is pretty similar to a Thunderbolt in terms of what they did for circuits. It’s by no means identical and I have not traced either one out far enough to have a schematic. At least from the TBolt - your DAC is working. The voltage is moving around and it’s getting low enough to bring the oscillator into lock. That suggests that the problem is not the DAC it’s self. I’d bet that what ever magic they do to figure out the oscillator frequency has gone nuts. A very common approach is to use the GPS PPS like a gate on a frequency counter. I think that this part gets a bit more fancy than that. Either way, that sounds like where the problem lies. Just in case - always check the regulated power supply voltages on the board and touch test the bypass caps. It’s a silly thing, but it doesn’t take long to do. I know I have gone for a few hours / days / weeks on something like this, only to finally bump into the shorted bypass cap or dead regulator and go “h…..”. Bob On Nov 11, 2014, at 8:07 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hello, After 2 yeses of continuous operation my NTGS50AA turned its red led on and stopped working. A check with LH shows OSC: BAD and OSC age alarm assuming that the oscillator had aged too much. I didn't believe this because when working, the DAC control voltage was around 2.9 V, in fact near the middle of its range (0-5 V). Measuring the 10 MHz output it is high, about 4.46 Hz which agrees with the LH figures. I measured the oscillator EFC pin and it is struck at 5.02 V, not following the DAC voltages as reported by LH. I think that either the DAC is bad or an amplifier after it. Since I don't have any schematic and the oscillator covers the top layer the troubleshooting is difficult. Has anybody experienced this failure before?. Does anybody has an schematic, even a partial one? Since the unit now is operating open loop I observed the locking strategy of this GPSDO. First it waits about 12 minutes for warming (I don't know if it internally monitors the oven current or uses a fixed time). During this period it sets the DAC output to the initial value as stored in the EEPROM (3.0 V). When it thinks that it is warmed enough, the DAC is ramped in the right direction to intercept exactly 10 MHz (towards 0 in my case). If it reaches 0 then declares the alarm and the DAC voltage is set to half the initial value (1.5 V). Five minutes later it switch the DAC to 2,25 V and 17 seconds later it returns to 1.5 V and remains there for 4 min and a half. Then it goes up again to 2.5 V and after 10 seconds it goes down to 1.88 V and after some 14 minutes it goes down again to 1.5 V, it remains there for about 15 minutes and then it goes down to 1.14 V, remains there for 80 seconds and goes back to 2.5 V. It looks like it checks from time to time if it is able to control the oscillator or simply it does weird things once it thinks that the oscillator cannot be disciplined. I will appreciate very much any information.that can help my troubleshooting. These units has more than doubled its price since I bought mine and I think that they are vanishing. The Guatemala's cell towers scrap has been exhausted. Regards, Ignacio EB4APL ___ 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] 10 MHz OCXO recommendations
Mark wrote: I find the concept of occasionally adjusting a good OCXO which in turn is used as a reference works well for me.I have some that haven't needed adjustment for over 2 years (they are still well within one part per billion of being on frequency.) A few of us have advocated this approach on the list, and there is good reason for it. A GPSDO offers two advantages: (1) it is self-adjusting, therefore easy to own and use; and (2) it has better stability at long tau than the OCXO alone. The price you pay for those advantages is poorer stability at low tau than the OCXO alone, which can be anywhere from slight with a good design (e.g., Thunderbolt, Z3801) to shockingly bad with a bad design (including many DIY attempts). If one does not need the very best performance at long tau -- and most time-nuts do not -- a free-running OCXO that you adjust manually every now and then can be the best reference available to the average time nut. (Long tau can be anywhere from 100 seconds to several thousand seconds, depending on the particular OCXO.) Plus, not spending money on GPS discipline allows you to spend more on the OCXO to get better stability at low tau, and a more extended upper limit on low tau (say, better than GPS all the way to 2000 seconds instead of 200 seconds). Personally, I do use GPS discipline to keep my best OCXO in perpetual adjustment, but that is mostly for convenience. Usually, I turn disciplining off when I'm taking data. Only when I'm doing something where the data are averaged for longer than about 3000 seconds do I leave it on (3000 seconds is based on the stability of my particular OCXO). Remember, GPS has a well-defined stability floor, and is not better than a good OCXO at averaging times (tau) less than 100 or even 1000 seconds -- so GPS discipline cannot do anything to help the stability of a good OCXO at shorter tau than that. (Yes, it may be able to help a lousy OCXO or TCXO at lower tau -- but you can get a better OCXO than that for $20, so why bother?) There is so much focus on GPSDOs that I think many time nuts do not realize this fundamental fact. A few rules of thumb: -- An OCXO is the best low-tau reference most amateurs can afford -- GPS discipline cannot help at low tau because it is noisy -- Most of us do not need extreme stability at long tau And some general conclusions: -- Get the best OCXO you can find -- Enclose it (thermally isolated from the enclosure) -- Don't try to whip a so-so OCXO into shape with GPS discipline Finding a really good OCXO may take some effort. Some models are more likely to be really good than others (like the BVA that Mark mentioned, and some others that have been vetted in large numbers), but even then there can be large differences from sample to sample. So, one may need to sort through a number of them to find a really good one. If one doesn't have access to a clearly better oscillator for comparison, using the three-cornered hat technique with one's best oscillators is probably the best method available to the amateur time nut. Note that quartz oscillators tend to exhibit best stability if they are left on continuously, and stability may improve for a long time (months, perhaps even many months) after they are turned on, depending on how long they were off and how much trauma they received before being powered up again). The point is that GPS discipline is not always (and maybe, not usually) the best way to get the best stability possibile over the range of tau that is most important to amateur time nuts. Further, it takes very well-designed GPS discipline to improve things at long tau without making them worse at shorter tau, so GPS discipline can easily be a net negative (particularly since most of us do not need extreme stability at very long tau). So, a good OCXO that is manually adjusted from time to time as required will likely have the best stability most amateur time nuts can obtain, at the range of tau that is actually important for the applications to which it will be put. 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] 10 MHz OCXO recommendations
Hi The only gotcha is accuracy. If that is part of the equation, then even a pretty dumpy OCXO properly GPSDO’d will beat one that is a very good OCXO indeed. A darn good OCXO will age down in the 1x10^-11 per day range. In a bit over 10 days you may be past +/- 1x10^-10. An OCXO based GPSDO that holds 1x10^-10 “some of the time” is one that gets yelled at and kicked a lot . It all depends on what you are after. Bob On Nov 11, 2014, at 7:26 PM, Charles Steinmetz csteinm...@yandex.com wrote: Mark wrote: I find the concept of occasionally adjusting a good OCXO which in turn is used as a reference works well for me.I have some that haven't needed adjustment for over 2 years (they are still well within one part per billion of being on frequency.) A few of us have advocated this approach on the list, and there is good reason for it. A GPSDO offers two advantages: (1) it is self-adjusting, therefore easy to own and use; and (2) it has better stability at long tau than the OCXO alone. The price you pay for those advantages is poorer stability at low tau than the OCXO alone, which can be anywhere from slight with a good design (e.g., Thunderbolt, Z3801) to shockingly bad with a bad design (including many DIY attempts). If one does not need the very best performance at long tau -- and most time-nuts do not -- a free-running OCXO that you adjust manually every now and then can be the best reference available to the average time nut. (Long tau can be anywhere from 100 seconds to several thousand seconds, depending on the particular OCXO.) Plus, not spending money on GPS discipline allows you to spend more on the OCXO to get better stability at low tau, and a more extended upper limit on low tau (say, better than GPS all the way to 2000 seconds instead of 200 seconds). Personally, I do use GPS discipline to keep my best OCXO in perpetual adjustment, but that is mostly for convenience. Usually, I turn disciplining off when I'm taking data. Only when I'm doing something where the data are averaged for longer than about 3000 seconds do I leave it on (3000 seconds is based on the stability of my particular OCXO). Remember, GPS has a well-defined stability floor, and is not better than a good OCXO at averaging times (tau) less than 100 or even 1000 seconds -- so GPS discipline cannot do anything to help the stability of a good OCXO at shorter tau than that. (Yes, it may be able to help a lousy OCXO or TCXO at lower tau -- but you can get a better OCXO than that for $20, so why bother?) There is so much focus on GPSDOs that I think many time nuts do not realize this fundamental fact. A few rules of thumb: -- An OCXO is the best low-tau reference most amateurs can afford -- GPS discipline cannot help at low tau because it is noisy -- Most of us do not need extreme stability at long tau And some general conclusions: -- Get the best OCXO you can find -- Enclose it (thermally isolated from the enclosure) -- Don't try to whip a so-so OCXO into shape with GPS discipline Finding a really good OCXO may take some effort. Some models are more likely to be really good than others (like the BVA that Mark mentioned, and some others that have been vetted in large numbers), but even then there can be large differences from sample to sample. So, one may need to sort through a number of them to find a really good one. If one doesn't have access to a clearly better oscillator for comparison, using the three-cornered hat technique with one's best oscillators is probably the best method available to the amateur time nut. Note that quartz oscillators tend to exhibit best stability if they are left on continuously, and stability may improve for a long time (months, perhaps even many months) after they are turned on, depending on how long they were off and how much trauma they received before being powered up again). The point is that GPS discipline is not always (and maybe, not usually) the best way to get the best stability possibile over the range of tau that is most important to amateur time nuts. Further, it takes very well-designed GPS discipline to improve things at long tau without making them worse at shorter tau, so GPS discipline can easily be a net negative (particularly since most of us do not need extreme stability at very long tau). So, a good OCXO that is manually adjusted from time to time as required will likely have the best stability most amateur time nuts can obtain, at the range of tau that is actually important for the applications to which it will be put. 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
[time-nuts] My NTGS50AA failed
I have seen this caused by the oscillator not responding to the EFC signal. Fixed it by swapping in a MV-89 oscillator. The oscillators used in these units don't output an oven temperature monitor signal. ___ 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] My NTGS50AA failed
Hi, I meant 2 years, it is quite late here. I'm not very sure that the DAC is working, I suppose that the unit doesn't measure the DAC output, it reports the DAC commands. My voltage figures is what LH reports (so the NTGS50AA reports, probably what it is trying to do), but the frequency control pin of the oscillator is stuck at 5.02 V regardless of the supposed (intended) DAC output, it does not move at all. I have checked the internal power supply voltages and they are ok. Hopefully a capacitor could be shorted to the +5V line but it looks too much luck for me. Thank you for your suggestions, Ignacio EB4APL On 12/11/2014 a las 2:23, Bob Camp wrote: Hi Ok, the gizmo you have is pretty similar to a Thunderbolt in terms of what they did for circuits. It’s by no means identical and I have not traced either one out far enough to have a schematic. At least from the TBolt - your DAC is working. The voltage is moving around and it’s getting low enough to bring the oscillator into lock. That suggests that the problem is not the DAC it’s self. I’d bet that what ever magic they do to figure out the oscillator frequency has gone nuts. A very common approach is to use the GPS PPS like a gate on a frequency counter. I think that this part gets a bit more fancy than that. Either way, that sounds like where the problem lies. Just in case - always check the regulated power supply voltages on the board and touch test the bypass caps. It’s a silly thing, but it doesn’t take long to do. I know I have gone for a few hours / days / weeks on something like this, only to finally bump into the shorted bypass cap or dead regulator and go “h…..”. Bob On Nov 11, 2014, at 8:07 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hello, After 2 yeses of continuous operation my NTGS50AA turned its red led on and stopped working. A check with LH shows OSC: BAD and OSC age alarm assuming that the oscillator had aged too much. I didn't believe this because when working, the DAC control voltage was around 2.9 V, in fact near the middle of its range (0-5 V). Measuring the 10 MHz output it is high, about 4.46 Hz which agrees with the LH figures. I measured the oscillator EFC pin and it is struck at 5.02 V, not following the DAC voltages as reported by LH. I think that either the DAC is bad or an amplifier after it. Since I don't have any schematic and the oscillator covers the top layer the troubleshooting is difficult. Has anybody experienced this failure before?. Does anybody has an schematic, even a partial one? Since the unit now is operating open loop I observed the locking strategy of this GPSDO. First it waits about 12 minutes for warming (I don't know if it internally monitors the oven current or uses a fixed time). During this period it sets the DAC output to the initial value as stored in the EEPROM (3.0 V). When it thinks that it is warmed enough, the DAC is ramped in the right direction to intercept exactly 10 MHz (towards 0 in my case). If it reaches 0 then declares the alarm and the DAC voltage is set to half the initial value (1.5 V). Five minutes later it switch the DAC to 2,25 V and 17 seconds later it returns to 1.5 V and remains there for 4 min and a half. Then it goes up again to 2.5 V and after 10 seconds it goes down to 1.88 V and after some 14 minutes it goes down again to 1.5 V, it remains there for about 15 minutes and then it goes down to 1.14 V, remains there for 80 seconds and goes back to 2.5 V. It looks like it checks from time to time if it is able to control the oscillator or simply it does weird things once it thinks that the oscillator cannot be disciplined. I will appreciate very much any information.that can help my troubleshooting. These units has more than doubled its price since I bought mine and I think that they are vanishing. The Guatemala's cell towers scrap has been exhausted. Regards, Ignacio EB4APL ___ 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] My NTGS50AA failed
Hi A .. I misunderstood what you were saying. As I now understand, the inputs to the DAC move around in the software, but the actual voltage out of the DAC is always stuck at 5V. The DAC (if it’s like a TBolt) is the sum of a set of signals into an op amp. There is a forest of metal film resistors and several amps in the setup. About the furthest I’ve gotten it to trace the signals past the first layer op amp and find that one of them is *way* off making the op amp rail. I’m sure that there is somebody who has taken that process further. It looks like a setup to sum several PWM outputs, but I could easily be wrong. Bob On Nov 11, 2014, at 8:47 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hi, I meant 2 years, it is quite late here. I'm not very sure that the DAC is working, I suppose that the unit doesn't measure the DAC output, it reports the DAC commands. My voltage figures is what LH reports (so the NTGS50AA reports, probably what it is trying to do), but the frequency control pin of the oscillator is stuck at 5.02 V regardless of the supposed (intended) DAC output, it does not move at all. I have checked the internal power supply voltages and they are ok. Hopefully a capacitor could be shorted to the +5V line but it looks too much luck for me. Thank you for your suggestions, Ignacio EB4APL On 12/11/2014 a las 2:23, Bob Camp wrote: Hi Ok, the gizmo you have is pretty similar to a Thunderbolt in terms of what they did for circuits. It’s by no means identical and I have not traced either one out far enough to have a schematic. At least from the TBolt - your DAC is working. The voltage is moving around and it’s getting low enough to bring the oscillator into lock. That suggests that the problem is not the DAC it’s self. I’d bet that what ever magic they do to figure out the oscillator frequency has gone nuts. A very common approach is to use the GPS PPS like a gate on a frequency counter. I think that this part gets a bit more fancy than that. Either way, that sounds like where the problem lies. Just in case - always check the regulated power supply voltages on the board and touch test the bypass caps. It’s a silly thing, but it doesn’t take long to do. I know I have gone for a few hours / days / weeks on something like this, only to finally bump into the shorted bypass cap or dead regulator and go “h…..”. Bob On Nov 11, 2014, at 8:07 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hello, After 2 yeses of continuous operation my NTGS50AA turned its red led on and stopped working. A check with LH shows OSC: BAD and OSC age alarm assuming that the oscillator had aged too much. I didn't believe this because when working, the DAC control voltage was around 2.9 V, in fact near the middle of its range (0-5 V). Measuring the 10 MHz output it is high, about 4.46 Hz which agrees with the LH figures. I measured the oscillator EFC pin and it is struck at 5.02 V, not following the DAC voltages as reported by LH. I think that either the DAC is bad or an amplifier after it. Since I don't have any schematic and the oscillator covers the top layer the troubleshooting is difficult. Has anybody experienced this failure before?. Does anybody has an schematic, even a partial one? Since the unit now is operating open loop I observed the locking strategy of this GPSDO. First it waits about 12 minutes for warming (I don't know if it internally monitors the oven current or uses a fixed time). During this period it sets the DAC output to the initial value as stored in the EEPROM (3.0 V). When it thinks that it is warmed enough, the DAC is ramped in the right direction to intercept exactly 10 MHz (towards 0 in my case). If it reaches 0 then declares the alarm and the DAC voltage is set to half the initial value (1.5 V). Five minutes later it switch the DAC to 2,25 V and 17 seconds later it returns to 1.5 V and remains there for 4 min and a half. Then it goes up again to 2.5 V and after 10 seconds it goes down to 1.88 V and after some 14 minutes it goes down again to 1.5 V, it remains there for about 15 minutes and then it goes down to 1.14 V, remains there for 80 seconds and goes back to 2.5 V. It looks like it checks from time to time if it is able to control the oscillator or simply it does weird things once it thinks that the oscillator cannot be disciplined. I will appreciate very much any information.that can help my troubleshooting. These units has more than doubled its price since I bought mine and I think that they are vanishing. The Guatemala's cell towers scrap has been exhausted. Regards, Ignacio EB4APL ___ 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] Second Units? KS-24361
Bob I will say that I am watching the noise of the pps ti in the z3811 program. Granted its been running 30 some hours now. Virtually nothing in time. My fingers are crossed it will clean up. I do like the unit quite well. Have to thank Bert for even cluing me in. So I do agree quite a nice unit. Regards Paul WB8TSL On Tue, Nov 11, 2014 at 7:42 PM, Bob Camp kb...@n1k.org wrote: Hi Here’s another way to look at the second unit - What would you pay (on an auction site) for the parts? Since there’s a warranty on the box, all would be 100% good working parts with a solid guarantee and paid shipping back: Lucent low EMI DC-DC converter “power brick” - $35 + $5 ship MTI 260 OCXO $35 + $15 ship Nice board built up with GPSDO parts $ (gotta be at least 20) + ship Metal enclosure $ (ok, it’s not that good, $5) Connectors, buffering, filtering $ something Just the two big parts in the box likely would set you back more than the cost of the second unit delivered in the US. If you are headed into a GPSDO project, the thing is a steal. Bob On Nov 10, 2014, at 1:41 AM, F. W. Bray fwb...@mminternet.com wrote: Sorry, I intended to say that this question concerns the KS-24361 units. Forgot to put that in the subject line! I have one complete setup on the way. Any thoughts as to whether it is better to get a second complete set or just go for the unit that has the GPS in it? This would be as a spare or possibly actual use. Thanks. Fred KE6CD ___ 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] My NTGS50AA failed
Hi, Removing the oscillator for testing and replacing it with other if it was the culprit was my first option. I have a spare Trimble oscillator that probably came from other NTGS50AA since it still have the foam band attached, but this oscillator is really aged, it needs 7.91 V to bring it on spot and the maximum control voltage of the NTGS50AA is 5 V. I was trying to avoid removing the oscillator but probably it must be done to clarify things. Thank you, Ignacio EB4APL . El 12/11/2014 a las 2:40, Mark Sims escribió: I have seen this caused by the oscillator not responding to the EFC signal. Fixed it by swapping in a MV-89 oscillator. The oscillators used in these units don't output an oven temperature monitor signal. ___ 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] Second Units? KS-24361
Hi Paul, I saw the phase of the 10MHz signal dip by about 60ns twice today as compared to my homebrew GPSDO. Given what I know about the design of my unit, it's hard to believe it could follow the path the phase difference took, but I suppose anything's possible. Bob posted a graph showing the KS moving about +/- 15ns recently. I would certainly like to know if others have seen this big of a phase movement. It's been on about a week since the last power-off to replace REF-1. Bob - AE6RV From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, November 11, 2014 7:55 PM Subject: Re: [time-nuts] Second Units? KS-24361 Bob I will say that I am watching the noise of the pps ti in the z3811 program. Granted its been running 30 some hours now. Virtually nothing in time. My fingers are crossed it will clean up. I do like the unit quite well. Have to thank Bert for even cluing me in. So I do agree quite a nice unit. Regards Paul WB8TSL On Tue, Nov 11, 2014 at 7:42 PM, Bob Camp kb...@n1k.org wrote: Hi Here’s another way to look at the second unit - What would you pay (on an auction site) for the parts? Since there’s a warranty on the box, all would be 100% good working parts with a solid guarantee and paid shipping back: Lucent low EMI DC-DC converter “power brick” - $35 + $5 ship MTI 260 OCXO $35 + $15 ship Nice board built up with GPSDO parts $ (gotta be at least 20) + ship Metal enclosure $ (ok, it’s not that good, $5) Connectors, buffering, filtering $ something Just the two big parts in the box likely would set you back more than the cost of the second unit delivered in the US. If you are headed into a GPSDO project, the thing is a steal. Bob On Nov 10, 2014, at 1:41 AM, F. W. Bray fwb...@mminternet.com wrote: Sorry, I intended to say that this question concerns the KS-24361 units. Forgot to put that in the subject line! I have one complete setup on the way. Any thoughts as to whether it is better to get a second complete set or just go for the unit that has the GPS in it? This would be as a spare or possibly actual use. Thanks. Fred KE6CD ___ 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. ___ 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] My NTGS50AA failed
Hi, I found in the top side a quad op amp, a LT 1014, surrounded by your forest of resistors. The output of one of these op amps goes directly to the control voltage input. I'm in the right track. It is very late here, 03:15 AM so I must go to the bed. Working so late is a call for disasters ... Best regards, Ignacio EB4APL El 12/11/2014 a las 2:54, Bob Camp escribió: Hi A .. I misunderstood what you were saying. As I now understand, the inputs to the DAC move around in the software, but the actual voltage out of the DAC is always stuck at 5V. The DAC (if it’s like a TBolt) is the sum of a set of signals into an op amp. There is a forest of metal film resistors and several amps in the setup. About the furthest I’ve gotten it to trace the signals past the first layer op amp and find that one of them is *way* off making the op amp rail. I’m sure that there is somebody who has taken that process further. It looks like a setup to sum several PWM outputs, but I could easily be wrong. Bob On Nov 11, 2014, at 8:47 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hi, I meant 2 years, it is quite late here. I'm not very sure that the DAC is working, I suppose that the unit doesn't measure the DAC output, it reports the DAC commands. My voltage figures is what LH reports (so the NTGS50AA reports, probably what it is trying to do), but the frequency control pin of the oscillator is stuck at 5.02 V regardless of the supposed (intended) DAC output, it does not move at all. I have checked the internal power supply voltages and they are ok. Hopefully a capacitor could be shorted to the +5V line but it looks too much luck for me. Thank you for your suggestions, Ignacio EB4APL On 12/11/2014 a las 2:23, Bob Camp wrote: Hi Ok, the gizmo you have is pretty similar to a Thunderbolt in terms of what they did for circuits. It’s by no means identical and I have not traced either one out far enough to have a schematic. At least from the TBolt - your DAC is working. The voltage is moving around and it’s getting low enough to bring the oscillator into lock. That suggests that the problem is not the DAC it’s self. I’d bet that what ever magic they do to figure out the oscillator frequency has gone nuts. A very common approach is to use the GPS PPS like a gate on a frequency counter. I think that this part gets a bit more fancy than that. Either way, that sounds like where the problem lies. Just in case - always check the regulated power supply voltages on the board and touch test the bypass caps. It’s a silly thing, but it doesn’t take long to do. I know I have gone for a few hours / days / weeks on something like this, only to finally bump into the shorted bypass cap or dead regulator and go “h…..”. Bob On Nov 11, 2014, at 8:07 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hello, After 2 yeses of continuous operation my NTGS50AA turned its red led on and stopped working. A check with LH shows OSC: BAD and OSC age alarm assuming that the oscillator had aged too much. I didn't believe this because when working, the DAC control voltage was around 2.9 V, in fact near the middle of its range (0-5 V). Measuring the 10 MHz output it is high, about 4.46 Hz which agrees with the LH figures. I measured the oscillator EFC pin and it is struck at 5.02 V, not following the DAC voltages as reported by LH. I think that either the DAC is bad or an amplifier after it. Since I don't have any schematic and the oscillator covers the top layer the troubleshooting is difficult. Has anybody experienced this failure before?. Does anybody has an schematic, even a partial one? Since the unit now is operating open loop I observed the locking strategy of this GPSDO. First it waits about 12 minutes for warming (I don't know if it internally monitors the oven current or uses a fixed time). During this period it sets the DAC output to the initial value as stored in the EEPROM (3.0 V). When it thinks that it is warmed enough, the DAC is ramped in the right direction to intercept exactly 10 MHz (towards 0 in my case). If it reaches 0 then declares the alarm and the DAC voltage is set to half the initial value (1.5 V). Five minutes later it switch the DAC to 2,25 V and 17 seconds later it returns to 1.5 V and remains there for 4 min and a half. Then it goes up again to 2.5 V and after 10 seconds it goes down to 1.88 V and after some 14 minutes it goes down again to 1.5 V, it remains there for about 15 minutes and then it goes down to 1.14 V, remains there for 80 seconds and goes back to 2.5 V. It looks like it checks from time to time if it is able to control the oscillator or simply it does weird things once it thinks that the oscillator cannot be disciplined. I will appreciate very much any information.that can help my troubleshooting. These units has more than doubled its price since I bought mine and I think that they are vanishing. The Guatemala's cell towers scrap has
Re: [time-nuts] My NTGS50AA failed
Ignacio wrote: I'm not very sure that the DAC is working, I suppose that the unit doesn't measure the DAC output, it reports the DAC commands. My voltage figures is what LH reports (so the NTGS50AA reports, probably what it is trying to do), but the frequency control pin of the oscillator is stuck at 5.02 V regardless of the supposed (intended) DAC output, it does not move at all. I'm not sure I understand what you've measured. I take it you have measured the EFC pin on the OCXO, and it reads 5.02v? Have you also determined what the voltage is on the DAC output pin? (Are they connected directly together, or is there a resistor or other circuitry between them?) If they are both at 5.02v, you need to disconnect them and see which one is pulling the node to that voltage (it could be an internal failure in the OCXO). 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] Second Units? KS-24361
I was thinking about snapping a pix. Though it has to be pretty small to get through time-nuts. Clearly my units still aging/adjusting a positive EFC rate. Regards Paul WB8TSL On Tue, Nov 11, 2014 at 9:12 PM, Bob Stewart b...@evoria.net wrote: Hi Paul, I saw the phase of the 10MHz signal dip by about 60ns twice today as compared to my homebrew GPSDO. Given what I know about the design of my unit, it's hard to believe it could follow the path the phase difference took, but I suppose anything's possible. Bob posted a graph showing the KS moving about +/- 15ns recently. I would certainly like to know if others have seen this big of a phase movement. It's been on about a week since the last power-off to replace REF-1. Bob - AE6RV From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, November 11, 2014 7:55 PM Subject: Re: [time-nuts] Second Units? KS-24361 Bob I will say that I am watching the noise of the pps ti in the z3811 program. Granted its been running 30 some hours now. Virtually nothing in time. My fingers are crossed it will clean up. I do like the unit quite well. Have to thank Bert for even cluing me in. So I do agree quite a nice unit. Regards Paul WB8TSL On Tue, Nov 11, 2014 at 7:42 PM, Bob Camp kb...@n1k.org wrote: Hi Here’s another way to look at the second unit - What would you pay (on an auction site) for the parts? Since there’s a warranty on the box, all would be 100% good working parts with a solid guarantee and paid shipping back: Lucent low EMI DC-DC converter “power brick” - $35 + $5 ship MTI 260 OCXO $35 + $15 ship Nice board built up with GPSDO parts $ (gotta be at least 20) + ship Metal enclosure$ (ok, it’s not that good, $5) Connectors, buffering, filtering $ something Just the two big parts in the box likely would set you back more than the cost of the second unit delivered in the US. If you are headed into a GPSDO project, the thing is a steal. Bob On Nov 10, 2014, at 1:41 AM, F. W. Bray fwb...@mminternet.com wrote: Sorry, I intended to say that this question concerns the KS-24361 units. Forgot to put that in the subject line! I have one complete setup on the way. Any thoughts as to whether it is better to get a second complete set or just go for the unit that has the GPS in it? This would be as a spare or possibly actual use. Thanks. Fred KE6CD ___ 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. ___ 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] Second Units? KS-24361
Paul, Large plots are ok. They just get flagged by the server for approval. /tvb (i5s) On Nov 11, 2014, at 8:03 PM, paul swed paulsw...@gmail.com wrote: I was thinking about snapping a pix. Though it has to be pretty small to get through time-nuts. Clearly my units still aging/adjusting a positive EFC rate. Regards Paul WB8TSL On Tue, Nov 11, 2014 at 9:12 PM, Bob Stewart b...@evoria.net wrote: Hi Paul, I saw the phase of the 10MHz signal dip by about 60ns twice today as compared to my homebrew GPSDO. Given what I know about the design of my unit, it's hard to believe it could follow the path the phase difference took, but I suppose anything's possible. Bob posted a graph showing the KS moving about +/- 15ns recently. I would certainly like to know if others have seen this big of a phase movement. It's been on about a week since the last power-off to replace REF-1. Bob - AE6RV From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, November 11, 2014 7:55 PM Subject: Re: [time-nuts] Second Units? KS-24361 Bob I will say that I am watching the noise of the pps ti in the z3811 program. Granted its been running 30 some hours now. Virtually nothing in time. My fingers are crossed it will clean up. I do like the unit quite well. Have to thank Bert for even cluing me in. So I do agree quite a nice unit. Regards Paul WB8TSL On Tue, Nov 11, 2014 at 7:42 PM, Bob Camp kb...@n1k.org wrote: Hi Here’s another way to look at the second unit - What would you pay (on an auction site) for the parts? Since there’s a warranty on the box, all would be 100% good working parts with a solid guarantee and paid shipping back: Lucent low EMI DC-DC converter “power brick” - $35 + $5 ship MTI 260 OCXO $35 + $15 ship Nice board built up with GPSDO parts $ (gotta be at least 20) + ship Metal enclosure$ (ok, it’s not that good, $5) Connectors, buffering, filtering $ something Just the two big parts in the box likely would set you back more than the cost of the second unit delivered in the US. If you are headed into a GPSDO project, the thing is a steal. Bob On Nov 10, 2014, at 1:41 AM, F. W. Bray fwb...@mminternet.com wrote: Sorry, I intended to say that this question concerns the KS-24361 units. Forgot to put that in the subject line! I have one complete setup on the way. Any thoughts as to whether it is better to get a second complete set or just go for the unit that has the GPS in it? This would be as a spare or possibly actual use. Thanks. Fred KE6CD ___ 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. ___ 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] My NTGS50AA failed
Ignacio wrote: I'm not very sure that the DAC is working, I suppose that the unit doesn't measure the DAC output, it reports the DAC commands. My voltage figures is what LH reports (so the NTGS50AA reports, probably what it is trying to do), but the frequency control pin of the oscillator is stuck at 5.02 V regardless of the supposed (intended) DAC output, it does not move at all. One more thing that could be helpful -- on Nov. 2, 2013 Stewart Cobb posted a description of the DAC operation for a Trimble Thunderbolt (Thunderbolt tuning DAC theory of operation). On Jan. 5, 2014 someone (no name) posted further information on the same thread re: the Trimble/Nortel 45k. You can find both posts in the list archives (follow the link at the bottom of this post, then click time-nuts Archives on the list home page). 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.
