[time-nuts] Morion MV89 and LTC6957
Hello there, I'm trying to build a low phase noise signal generator with a Morion MV89 OCXO. ( http://www.morion.com.ru/catalog_pdf/MV89-OCXO.pdf ) The 10 MHz Sine coming from the MV89 shall be converted to a 10 MHz rectangle with the LTC6957-3 ( http://cds.linear.com/docs/en/datasheet/6957f.pdf ). Since the information in the MV89's data sheet is rather thin and shipping is taking a lot longer than expected/promised, I thought I'd ask if someone here has any experience with it and maybe can answer some questions I have... 1. Does anyone know if the MV89 is internally AC coupled / if the Output Sine has an Offset? 2. I'm not sure if termination is needed in this case or which way to terminate would be best for a low phase noise/low jitter application. Can anyone give me some hints to what would be important? Thanks a lot! ___ 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] Morion MV89 and LTC6957
It is AC coupled. In fact, many of these units have a bad capacitor and a very low output. If you get one like that, you will need to open the can and replace the SMT capacitor. I believe it is designed to drive a 50 ohm load but I do not know what effect that will have on the phase noise. Regards, Tom ___ 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] Morion MV89 and LTC6957
One thing to be aware of on the MV89 is that it is a 5 MHz osc that uses a freq doubler. On the ones I've tested, without further filtering, every other cycle's period is different by ~ 1 ns or so. For a time nut that likes to see 1ps jitter, it is a whole lot of cycle to cycle edge jitter that shows up on any signal that is divided down by a non 2 to n divider. The second thing I've seen is that the output Cap is open in a large number of them. ws ** Hello there, I'm trying to build a low phase noise signal generator with a Morion MV89 OCXO. ( http://www.morion.com.ru/catalog_pdf/MV89-OCXO.pdf ) The 10 MHz Sine coming from the MV89 shall be converted to a 10 MHz rectangle with the LTC6957-3 ( http://cds.linear.com/docs/en/datasheet/6957f.pdf ). Since the information in the MV89's data sheet is rather thin and shipping is taking a lot longer than expected/promised, I thought I'd ask if someone here has any experience with it and maybe can answer some questions I have... 1. Does anyone know if the MV89 is internally AC coupled / if the Output Sine has an Offset? 2. I'm not sure if termination is needed in this case or which way to terminate would be best for a low phase noise/low jitter application. Can anyone give me some hints to what would be important? Thanks a lot! ___ 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] Morion MV89 and LTC6957
Hi You would want a 50 ohm load on the output of the OCXO. Based on recent experience, you may have to buy 10 or more before you find one that is reasonably close to working correctly. The low output issues are far from the only problem on these units. Bob On Nov 6, 2013, at 9:27 AM, HagaaarTheHorrible hagaaar587pl...@googlemail.com wrote: Hello there, I'm trying to build a low phase noise signal generator with a Morion MV89 OCXO. ( http://www.morion.com.ru/catalog_pdf/MV89-OCXO.pdf ) The 10 MHz Sine coming from the MV89 shall be converted to a 10 MHz rectangle with the LTC6957-3 ( http://cds.linear.com/docs/en/datasheet/6957f.pdf ). Since the information in the MV89's data sheet is rather thin and shipping is taking a lot longer than expected/promised, I thought I'd ask if someone here has any experience with it and maybe can answer some questions I have... 1. Does anyone know if the MV89 is internally AC coupled / if the Output Sine has an Offset? 2. I'm not sure if termination is needed in this case or which way to terminate would be best for a low phase noise/low jitter application. Can anyone give me some hints to what would be important? Thanks a lot! ___ 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] Morion MV89 and LTC6957
Ok... maybe i´ll make a not so smart question but... if the MV89 is bad, what´s the recomended parts from ebay for something like that? (10MHz OCXO to upgrade some sort of equipment) (I´m asking because I did almost the same thing than our friend Hagar... I noticed that the MV89 wasn´t as good as I would like it to be). Daniel Em 06/11/2013 20:29, Bob Camp escreveu: Hi You would want a 50 ohm load on the output of the OCXO. Based on recent experience, you may have to buy 10 or more before you find one that is reasonably close to working correctly. The low output issues are far from the only problem on these units. Bob On Nov 6, 2013, at 9:27 AM, HagaaarTheHorrible hagaaar587pl...@googlemail.com wrote: Hello there, I'm trying to build a low phase noise signal generator with a Morion MV89 OCXO. ( http://www.morion.com.ru/catalog_pdf/MV89-OCXO.pdf ) The 10 MHz Sine coming from the MV89 shall be converted to a 10 MHz rectangle with the LTC6957-3 ( http://cds.linear.com/docs/en/datasheet/6957f.pdf ). Since the information in the MV89's data sheet is rather thin and shipping is taking a lot longer than expected/promised, I thought I'd ask if someone here has any experience with it and maybe can answer some questions I have... 1. Does anyone know if the MV89 is internally AC coupled / if the Output Sine has an Offset? 2. I'm not sure if termination is needed in this case or which way to terminate would be best for a low phase noise/low jitter application. Can anyone give me some hints to what would be important? Thanks a lot! ___ 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] Morion MV89 and LTC6957
Hi All of the eBay OCXO’s are pulled from scrap gear. If they have been on eBay for a while, it’s a good bet that the gear has been pretty well picked over. The only time you can get fairly good parts is when the first hit the market. Bob On Nov 6, 2013, at 5:54 PM, Daniel Mendes dmend...@gmail.com wrote: Ok... maybe i´ll make a not so smart question but... if the MV89 is bad, what´s the recomended parts from ebay for something like that? (10MHz OCXO to upgrade some sort of equipment) (I´m asking because I did almost the same thing than our friend Hagar... I noticed that the MV89 wasn´t as good as I would like it to be). Daniel Em 06/11/2013 20:29, Bob Camp escreveu: Hi You would want a 50 ohm load on the output of the OCXO. Based on recent experience, you may have to buy 10 or more before you find one that is reasonably close to working correctly. The low output issues are far from the only problem on these units. Bob On Nov 6, 2013, at 9:27 AM, HagaaarTheHorrible hagaaar587pl...@googlemail.com wrote: Hello there, I'm trying to build a low phase noise signal generator with a Morion MV89 OCXO. ( http://www.morion.com.ru/catalog_pdf/MV89-OCXO.pdf ) The 10 MHz Sine coming from the MV89 shall be converted to a 10 MHz rectangle with the LTC6957-3 ( http://cds.linear.com/docs/en/datasheet/6957f.pdf ). Since the information in the MV89's data sheet is rather thin and shipping is taking a lot longer than expected/promised, I thought I'd ask if someone here has any experience with it and maybe can answer some questions I have... 1. Does anyone know if the MV89 is internally AC coupled / if the Output Sine has an Offset? 2. I'm not sure if termination is needed in this case or which way to terminate would be best for a low phase noise/low jitter application. Can anyone give me some hints to what would be important? Thanks a lot! ___ 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] Trimble 34310-T EFC Question
I think I may need to change the LPF feeding the EFC in my GPSDO to get rid of dithering jitter. Is there any point in adding a resistor and cap in the EFC line, or do I need to go back and change the values in the op-amp circuit feeding it? Currently an op-amp directly feeds the EFC pin. I guess this boils down to something like: is there any meaningful current flow in EFC circuit in this oscillator? Or should I add them but will I probably have to change the existing filter, as well? Bob - AE6RV ___ 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] Trimble 34310-T EFC Question
Hello Bob, If you think you are getting any high frequency into the EFC control - it may be worth putting a(nother) low-pass filter in there. Are you measuring noise on that line? Do you have a snap-shot of a schematic? Or, can you take a picture of that circuit? I would hazard a guess you don't want to change the op-amp in such a way the gain is too high - the circuit could be designed for unity gain. A different choice in resistors could still yield unity gain and maybe knock down the noise a bit. I would need to put an ammeter in the circuit to determine if there was any meaningful current flow - without injecting noise of course... ;) 73's, John AJ6BC On Wed, Nov 6, 2013 at 7:26 PM, Bob Stewart b...@evoria.net wrote: I think I may need to change the LPF feeding the EFC in my GPSDO to get rid of dithering jitter. Is there any point in adding a resistor and cap in the EFC line, or do I need to go back and change the values in the op-amp circuit feeding it? Currently an op-amp directly feeds the EFC pin. I guess this boils down to something like: is there any meaningful current flow in EFC circuit in this oscillator? Or should I add them but will I probably have to change the existing filter, as well? Bob - AE6RV ___ 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] Trimble 34310-T EFC Question
Bob, Most EFC circuits are relatively high impedance, i.e., around 50K. So, we are talking micro amps of current flow. If there is jitter it is most likely somewhere else in the circuitry OR you are seeing the natural noise in the GPS system. BillWB6BNQ Bob Stewart wrote: I think I may need to change the LPF feeding the EFC in my GPSDO to get rid of dithering jitter. Is there any point in adding a resistor and cap in the EFC line, or do I need to go back and change the values in the op-amp circuit feeding it? Currently an op-amp directly feeds the EFC pin. I guess this boils down to something like: is there any meaningful current flow in EFC circuit in this oscillator? Or should I add them but will I probably have to change the existing filter, as well? Bob - AE6RV ___ 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] Computing GPS Distance Error in Time
Mark, What type of real-time surveying software are you using? I'm looking for surveying/plotting software for Linux to keep a close on the timing stability of my Adafruit. Bob - AE6RV From: Mark Sims hol...@hotmail.com To: time-nuts@febo.com time-nuts@febo.com Sent: Monday, November 4, 2013 7:13 PM Subject: [time-nuts] Computing GPS Distance Error in Time I was using the Adafruit GPS receivers to calculate the bearing and distance between two boxes that had radio tranceivers in them. The control box polls the remote box position and does simple trig on the difference between the GPS coordinates. I noticed that the Adafruit GPS seems to go into some kind of funky position hold mode if thinks that it is not moving (or is actually moving very slowly)... the GPS coordinates stop updating until the box moves some distance. I got much better results using a CN06 GPS module that is based upon the Ublox Neo-6M. You need to solder a wire to the Neo module to access its PPS output. HobbyKing sells them for cheap... also lots of sellers on Ebay. I could put one box on the ground, and move the other one around it only a couple of feet away. It gave remarkably good results considering the boxes were much closer than the average GPS error... it is basically a differential GPS application. Also, the processor is an AVR running single precision floats. I laid out a breakout board that can take the Adafruit, CN06, or Trimble Resolution T GPS boards and convert the TTL/CMOS levels to true RS-232 levels via a MAX3232 chip to a DE-9 connector. PPS polarity is jumperable. ___ 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.
