[time-nuts] 8040c specification clarification, help for a time-nut beginner
I'm currently doing my master's thesis on GPSDO devices. Nothing fancy but more than enough for a fledgling time-nutter. It seems that which ever direction I go with my master's, this place always pops up :) I'm a bit uncertain about how to interpret one of the GPSDO's specifications. The device in question is a a 8040c Rubidium Frequency Standard with a SA.22C-LN oscillator (ie. the low noise version). The specification states that its frequency accuracy (ie frequency offset) after 20 minutes of 1PPS GPS-disciplining is 1E-12. Do you think this specification the combined accuracy of the GPS receiver and 8040c device? In another words, if the 8040c is locked to GPS, is the whole receiver+8040c system's combined accuracy 1E-12? The GPS receiver that I have in use is XLi-GPS with +-30ns RMS 1PPS output. The datasheet for 8040c is here: http://www.symmetricom.com/resources/download-library/documents/datasheets/8040c/ The measurements that I've done indicate that at least the frequency stability (ADEV) of the 8040c is between 9E-13 and 1E-12 from 1s to 1000s. Thanks in advance. ___ 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] 8040c specification clarification, help for a time-nut beginner
Welcome to the list. Congratulations on your masters effort. Which school? There is no way the 8040c can make a claim about output accuracy without some assumption about the short- and long-term quality of the 1PPS reference input. They just mention GPS so your question is a good one. But it's reasonable to assume they mean a clean 1PPS from a good GPS receiver under ideal conditions, or other fuzzy words to that effect. The other issue is that they don't mention over what interval the 1e-12 frequency accuracy is measured. Most GPSDO are accurate to 1e-12 or even 1e-13 over a day, but this does not mean it is accurate to that over any given minute or second. And to be picky, it that a one sigma accuracy spec or two or peak, etc. How did you measure the 1PPS of the XLi-GPS? Also, how did you measure the ADEV of the 8040c? Since this is for a masters, you can fully measure a 8040c without using GPS at all. Using your own reference (not GPS) just create a lab 1PPS with varying amounts of inaccuracy and see how well the 8040c tracks your reference. The resulting plot(s) would be wonderful and will show how well the 8040c disciplining works as a function of 1PPS accuracy, jitter, and wander. In this case, you don't have to fight any of the issues with an actual GPS receiver; that's a whole other can of worms. /tvb - Original Message - From: Pee Akka akka...@gmail.com To: time-nuts@febo.com Sent: Thursday, December 12, 2013 2:22 AM Subject: [time-nuts] 8040c specification clarification,help for a time-nut beginner I'm currently doing my master's thesis on GPSDO devices. Nothing fancy but more than enough for a fledgling time-nutter. It seems that which ever direction I go with my master's, this place always pops up :) I'm a bit uncertain about how to interpret one of the GPSDO's specifications. The device in question is a a 8040c Rubidium Frequency Standard with a SA.22C-LN oscillator (ie. the low noise version). The specification states that its frequency accuracy (ie frequency offset) after 20 minutes of 1PPS GPS-disciplining is 1E-12. Do you think this specification the combined accuracy of the GPS receiver and 8040c device? In another words, if the 8040c is locked to GPS, is the whole receiver+8040c system's combined accuracy 1E-12? The GPS receiver that I have in use is XLi-GPS with +-30ns RMS 1PPS output. The datasheet for 8040c is here: http://www.symmetricom.com/resources/download-library/documents/datasheets/8040c/ The measurements that I've done indicate that at least the frequency stability (ADEV) of the 8040c is between 9E-13 and 1E-12 from 1s to 1000s. Thanks in advance. ___ 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] Question about the FE-5680A
Hi all, I recently bought a second-hand FE-5680A for some light experimentation via ebay. There seems to be a number of variants floating around. Mine in particular lacks a J2 (where I would expect to see the 10 MHz connector), so I only have the DB9 J1 connector. The unit is working, If I supply 15V over DB9 pins 1/2, the unit heats up, after a while pin #3 drops to indicate a lock, and pin 6 shows a 1 microsecond wide PPS that I am happy to see, since that is what I am most interested in. I have a few questions: * Does anyone else have a unit that lacks a J2 10 MHz output? Is the intention of such a unit solely to provide a PPS? * Is there a way to tell which revision/Option I have, eg.via inquiry on the serial port? My unit has no Option indication, all I have is FE-5680A / UN17491 / serial nr. 27727W / Revision: B. Without opening the unit at least, there are no other visible markings. * J1-1 has function +15V, J1-2 is +15V return, which, as I understand it, means ground for the main power (I don't know how to interpret provides DC return other than that). However, there is also GROUND (J1-5), and there are at least the following signals: - J1-3 Loop Lock Indicator (output; appears to be 5V, with 5V meaning no lock) - J1-6 Manual says not used, but it carries a 1 us PPS (5V) - J1-8 RS-232 Rx (input for the FE-5680A) - J1-9 RS-232 Tx (output for the FE-5680A) Should I assume that pins 3, 6, 8, 9 are all in reference to the ground provided by pin 5? Is pin 2 only ground for the pin 1? Is there any relation between the voltage levels at pin #2 and pin #5? Any help is greatly appreciated! Sidney ___ 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] recommendations for master reference
I am currently using both Trimble Thunderbolt and LPRO-101 Rb references. What I really would like to have is a rack-mountable unit that is a GPS-disciplined Rb reference and a built-in NTP server. (Yes, this is for my home. We are time-nuts, aren't we?) I could roll-my-own system for disciplining the Rb from the 1pps of the Thunderbolt, and produce NTP broadcasts on the LAN but, frankly, I am going to be happier if I find a unit where someone has already done the heavy lifting AND done a better job with the filtering to reduce GPS-induced error in the Rb output. So, if you wanted a rack-mountable reference with multiple 10MHz outputs that is a GPS disciplined Rb and an NTP server, what would you look for on the used market? Oh, I suppose I would go for a Cs reference if I could find one at the right price. I'm not picky. :-) -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ 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] recommendations for master reference
On 12/12/13 6:31 AM, Brian Lloyd wrote: I am currently using both Trimble Thunderbolt and LPRO-101 Rb references. What I really would like to have is a rack-mountable unit that is a GPS-disciplined Rb reference and a built-in NTP server. (Yes, this is for my home. We are time-nuts, aren't we?) I could roll-my-own system for disciplining the Rb from the 1pps of the Thunderbolt, and produce NTP broadcasts on the LAN but, frankly, I am going to be happier if I find a unit where someone has already done the heavy lifting AND done a better job with the filtering to reduce GPS-induced error in the Rb output. So, if you wanted a rack-mountable reference with multiple 10MHz outputs that is a GPS disciplined Rb and an NTP server, what would you look for on the used market? TrueTime/Symmetricom made and still makes a whole line of just this sort of thing in a 1 U rack mount enclosure. Something like an XL-DC with the right plug in boards, for instance. The particular plug-in I've used in the past is the one with the quiet quartz oscillator with low phase noise (since I'm usually multiplying up to microwave frequencies), but they have plenty of other options. They also have NTP servers in the same box, IRIG, etc. Oh, I suppose I would go for a Cs reference if I could find one at the right price. I'm not picky. :-) ___ 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] Question about the FE-5680A
Sidney there are to many versions to count. But if you do not have 10 MHz on the DB9 pin 7 you should check if the XTAL Osc. is 60 MHz. You can bring 60 MHz out or divide internally make sure you divide first by three followed by a divide by two to get a symmetrical output. Also check the RS 232 output some are TTL no inversion some are RS levels. Look for a MAX 3232 while checking for 60 MHz. If the XTAL is 50.255 not so easy. Will have to add an externalDDS It it has 60 MHz and XC 9572XL chip, check pin 49 it may have 10 MHz out. Bert Kehren Miami In a message dated 12/12/2013 8:57:52 A.M. Eastern Standard Time, sid...@jigsaw.nl writes: Hi all, I recently bought a second-hand FE-5680A for some light experimentation via ebay. There seems to be a number of variants floating around. Mine in particular lacks a J2 (where I would expect to see the 10 MHz connector), so I only have the DB9 J1 connector. The unit is working, If I supply 15V over DB9 pins 1/2, the unit heats up, after a while pin #3 drops to indicate a lock, and pin 6 shows a 1 microsecond wide PPS that I am happy to see, since that is what I am most interested in. I have a few questions: * Does anyone else have a unit that lacks a J2 10 MHz output? Is the intention of such a unit solely to provide a PPS? * Is there a way to tell which revision/Option I have, eg.via inquiry on the serial port? My unit has no Option indication, all I have is FE-5680A / UN17491 / serial nr. 27727W / Revision: B. Without opening the unit at least, there are no other visible markings. * J1-1 has function +15V, J1-2 is +15V return, which, as I understand it, means ground for the main power (I don't know how to interpret provides DC return other than that). However, there is also GROUND (J1-5), and there are at least the following signals: - J1-3 Loop Lock Indicator (output; appears to be 5V, with 5V meaning no lock) - J1-6 Manual says not used, but it carries a 1 us PPS (5V) - J1-8 RS-232 Rx (input for the FE-5680A) - J1-9 RS-232 Tx (output for the FE-5680A) Should I assume that pins 3, 6, 8, 9 are all in reference to the ground provided by pin 5? Is pin 2 only ground for the pin 1? Is there any relation between the voltage levels at pin #2 and pin #5? Any help is greatly appreciated! Sidney ___ 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] Motorola GPS antenna type GCNT20A3A
I know Goldmine would not sell duff stuff knowingly, but the Engineering Sample label worries me a little. Often this is indicates a non-functioning item for display or trial fit purposes. Then again it maybe not. I can't find out as they don't ship outside the USA. Robert G8RPI. From: Russ Ramirez russ.rami...@gmail.com To: time-nuts@febo.com Sent: Wednesday, 11 December 2013, 23:57 Subject: [time-nuts] Motorola GPS antenna type GCNT20A3A FYI, in case anyone should be interested. $20 http://www.goldmine-elec-products.com/prodinfo.asp?number=G19738 Russ ___ 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] 8040c specification clarification, help for a time-nut beginner
Hi Pee: Here's some vocabulary to help you. The 8040c is a frequency standard, not a GPSDO. That's to say it doesn't have a GPS receiver built in, but instead requires an external 1 PPS input. It's very similar to the Stanford Research PRS-10 in that respect. http://www.prc68.com/I/PRS10.shtml The Thunderbolt is a combined GPS receiver and disciplined oscillator. http://www.prc68.com/I/ThunderBolt.shtml It's input is from a GPS antenna. Outputs are 1PPS and 10 MHz. The 1E-12 frequency accuracy after 20 minutes is not a specification, but rather a performance parameter. That may be because it may depend on the quality of the 1 PPS input. Note the Allan deviation at 1 second is not as good. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Pee Akka wrote: I'm currently doing my master's thesis on GPSDO devices. Nothing fancy but more than enough for a fledgling time-nutter. It seems that which ever direction I go with my master's, this place always pops up :) I'm a bit uncertain about how to interpret one of the GPSDO's specifications. The device in question is a a 8040c Rubidium Frequency Standard with a SA.22C-LN oscillator (ie. the low noise version). The specification states that its frequency accuracy (ie frequency offset) after 20 minutes of 1PPS GPS-disciplining is 1E-12. Do you think this specification the combined accuracy of the GPS receiver and 8040c device? In another words, if the 8040c is locked to GPS, is the whole receiver+8040c system's combined accuracy 1E-12? The GPS receiver that I have in use is XLi-GPS with +-30ns RMS 1PPS output. The datasheet for 8040c is here: http://www.symmetricom.com/resources/download-library/documents/datasheets/8040c/ The measurements that I've done indicate that at least the frequency stability (ADEV) of the 8040c is between 9E-13 and 1E-12 from 1s to 1000s. Thanks in advance. ___ 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] Motorola GPS antenna type GCNT20A3A
On 12/12/2013 1:29 PM, Robert Atkinson wrote: I know Goldmine would not sell duff stuff knowingly, but the Engineering Sample label worries me a little. Often this is indicates a non-functioning item for display or trial fit purposes. Then again it maybe not. I wondered about that as well, but they don't say anything like 'limited stock' which implies that they've got lots of them. Who would have a large stock of display units? I can't find out as they don't ship outside the USA. Actually, they do ship outside the USA, but only to an oddly restricted list of countries. http://www.goldmine-elec-products.com/Testimonials.asp I can't imagine why their shipping info page is named 'Testimonials', but that's what it is. Ed Robert G8RPI. From: Russ Ramirez russ.rami...@gmail.com To: time-nuts@febo.com Sent: Wednesday, 11 December 2013, 23:57 Subject: [time-nuts] Motorola GPS antenna type GCNT20A3A FYI, in case anyone should be interested. $20 http://www.goldmine-elec-products.com/prodinfo.asp?number=G19738 Russ ___ 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] Motorola GPS antenna type GCNT20A3A
They do ship internationally but to a limited number of countries. For some reason the UK is not on the list of those they will ship to. See their website under the 'shipping' tab. DaveB, NZ - Original Message - From: Robert Atkinson robert8...@yahoo.co.uk To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, December 13, 2013 8:29 AM Subject: Re: [time-nuts] Motorola GPS antenna type GCNT20A3A I know Goldmine would not sell duff stuff knowingly, but the Engineering Sample label worries me a little. Often this is indicates a non-functioning item for display or trial fit purposes. Then again it maybe not. I can't find out as they don't ship outside the USA. Robert G8RPI. From: Russ Ramirez russ.rami...@gmail.com To: time-nuts@febo.com Sent: Wednesday, 11 December 2013, 23:57 Subject: [time-nuts] Motorola GPS antenna type GCNT20A3A FYI, in case anyone should be interested. $20 http://www.goldmine-elec-products.com/prodinfo.asp?number=G19738 Russ ___ 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] Motorola GPS antenna type GCNT20A3A
This should be equivalent to the Synergy Timing 3000 antenna: http://www.synergy-gps.com/images/stories/pdf/anttiming3000_tn888.pdf. David N1HAC On 12/12/13 2:59 PM, Dave Brown wrote: They do ship internationally but to a limited number of countries. For some reason the UK is not on the list of those they will ship to. See their website under the 'shipping' tab. DaveB, NZ - Original Message - From: Robert Atkinson robert8...@yahoo.co.uk To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Friday, December 13, 2013 8:29 AM Subject: Re: [time-nuts] Motorola GPS antenna type GCNT20A3A I know Goldmine would not sell duff stuff knowingly, but the Engineering Sample label worries me a little. Often this is indicates a non-functioning item for display or trial fit purposes. Then again it maybe not. I can't find out as they don't ship outside the USA. Robert G8RPI. From: Russ Ramirez russ.rami...@gmail.com To: time-nuts@febo.com Sent: Wednesday, 11 December 2013, 23:57 Subject: [time-nuts] Motorola GPS antenna type GCNT20A3A FYI, in case anyone should be interested. $20 http://www.goldmine-elec-products.com/prodinfo.asp?number=G19738 Russ ___ 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] Schematic for the 'analog' section of an FE-5680A?
Hi, I’m an elderly time-nut newby, and I’ve already struck trouble with a used FE-5680 Rb-vapour reference I bought via eBay. It runs (from +16V and +5V), and the current drain starts at 1.75A and then drops over 5 minutes or so down to about 650mA. But it won’t lock, even if I leave it powered up for a few hours (with a fan to keep it from getting too hot). The output frequency just keeps switching up and down between about 850Hz and 1080Hz, with a bit of ‘lingering’ near each end. And of course the ‘lock’ output at pin 3 stays stubbornly at about 4.35V. To my newby brain, this sounds like the problem is either in the Rb lamp (too dark, perhaps), or else in the photodetector and buffer, etc, forming the ‘dip detector’ part of the feedback loop. Could one of you much-more-experienced time-nutters tell me if my diagnosis sounds right? Also, I’ve found a schematic for the digital sections of the FE-5680A in your archives, kindly drawn up by one of your very experienced members, but has anyone done a similar schematic for the ‘analog’ sections? I suspect I’m going to have to work out for myself where to test for a fault in these sections. There’s also a bit of a mystery (in my mind, at least) regarding that little 2-pin SIL header just near the Rb lamp, on the top of the PCB. Anyone know what that’s for? All the best in anticipation, folks. Jim Rowe ___ 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] Question about the FE-5680A
The FE5680A has about ten years of history on time-nuts. The FEI webpage bears little resemblance to most of the units that you will find. I have never seen one with a factory separate connector for oscillator output. Many needed both 15V and 5V to operate. Different versions have outputs for PPS and/or (x)MHz (some can be programmed for output frequency). I don't think there are any markings on the various versions that clearly identify what, exactly, their features might be. Members here have hacked the internals to describe two basic evolutions of design. I suggest you do some hours to weeks of reading and come back with any specific questions. Here are places to start... The KO4BB Wiki -- http://www.ko4bb.com/dokuwiki/doku.php -- scroll down to find a couple of FE5680A links. The time-nuts searchable archive -- http://www.mail-archive.com/time-nuts@febo.com/info.html -- put in 5680A or similar and get many many posts to read. On 12/12/2013 5:24 AM, Sidney Cadot wrote: Hi all, I recently bought a second-hand FE-5680A for some light experimentation via ebay. There seems to be a number of variants floating around. Mine in particular lacks a J2 (where I would expect to see the 10 MHz connector), so I only have the DB9 J1 connector. The unit is working, If I supply 15V over DB9 pins 1/2, the unit heats up, after a while pin #3 drops to indicate a lock, and pin 6 shows a 1 microsecond wide PPS that I am happy to see, since that is what I am most interested in. I have a few questions: * Does anyone else have a unit that lacks a J2 10 MHz output? Is the intention of such a unit solely to provide a PPS? * Is there a way to tell which revision/Option I have, eg.via inquiry on the serial port? My unit has no Option indication, all I have is FE-5680A / UN17491 / serial nr. 27727W / Revision: B. Without opening the unit at least, there are no other visible markings. * J1-1 has function +15V, J1-2 is +15V return, which, as I understand it, means ground for the main power (I don't know how to interpret provides DC return other than that). However, there is also GROUND (J1-5), and there are at least the following signals: - J1-3 Loop Lock Indicator (output; appears to be 5V, with 5V meaning no lock) - J1-6 Manual says not used, but it carries a 1 us PPS (5V) - J1-8 RS-232 Rx (input for the FE-5680A) - J1-9 RS-232 Tx (output for the FE-5680A) Should I assume that pins 3, 6, 8, 9 are all in reference to the ground provided by pin 5? Is pin 2 only ground for the pin 1? Is there any relation between the voltage levels at pin #2 and pin #5? Any help is greatly appreciated! Sidney ___ 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] recommendations for master reference
OK will add my 10 cents. Half the fun is building your homebrew $1.98 ref with NTP. Simply toss it on a 2 or 3 ru rack panel. The servers these days are itty bitty. Now for serious class follow Jims guidance. Regards Paul On Thu, Dec 12, 2013 at 10:07 AM, Jim Lux jim...@earthlink.net wrote: On 12/12/13 6:31 AM, Brian Lloyd wrote: I am currently using both Trimble Thunderbolt and LPRO-101 Rb references. What I really would like to have is a rack-mountable unit that is a GPS-disciplined Rb reference and a built-in NTP server. (Yes, this is for my home. We are time-nuts, aren't we?) I could roll-my-own system for disciplining the Rb from the 1pps of the Thunderbolt, and produce NTP broadcasts on the LAN but, frankly, I am going to be happier if I find a unit where someone has already done the heavy lifting AND done a better job with the filtering to reduce GPS-induced error in the Rb output. So, if you wanted a rack-mountable reference with multiple 10MHz outputs that is a GPS disciplined Rb and an NTP server, what would you look for on the used market? TrueTime/Symmetricom made and still makes a whole line of just this sort of thing in a 1 U rack mount enclosure. Something like an XL-DC with the right plug in boards, for instance. The particular plug-in I've used in the past is the one with the quiet quartz oscillator with low phase noise (since I'm usually multiplying up to microwave frequencies), but they have plenty of other options. They also have NTP servers in the same box, IRIG, etc. Oh, I suppose I would go for a Cs reference if I could find one at the right price. I'm not picky. :-) ___ 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] Shortt Clock Recent Measurements
The eccentric English physicist Boys made quartz fibres by attaching one end to a crossbow bolt, heating the middle and then firing the bolt, at what I have been unable to determine. He used this to measure the gravitational constant by suspending iron spheres from the resultant fibre, which of course was amazingly strong for it's diameter. Myself I'd use a pneumatic cannon, since I have one, rather than a crossbow. Tom Harris celephi...@gmail.com On 11 December 2013 15:55, Jim Lux jim...@earthlink.net wrote: On 12/10/13 5:57 PM, Don Latham wrote: I always thought invar was the magic metal. Quartz rod? You can get those at some reasonable cost? 12 mm dia fused qtz, about $10 per ft, so under $40 to get going, assuming 4 or 5 to learn how to do it right. It does break... 12.7 mm dia Invar 1 m long is $530 Amazing, and quartz is better (A single crystal would cost a pretty penny. I'm not sure a crystal that long can be drawn using a zone furnace). Pyrex is also available. These are quick 'net prices. John Strong's book tells how to make thin high-q fused silica fibers with an appropriate burner. Just the thing for your torsion balance, etc. back in the day when a self respecting experimental physicist built their own equipment. ___ 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] Schematic for the 'analog' section of an FE-5680A?
Jim I can add some info here. What you suggest is a reasonable conclusion. On some RB modules but I do not believe on the FE-5680s there is a true lamp voltage and its very helpful in determining if the lamps old enough that as you say its dark. On those units if you are below 4 volts approx you know the reference is pretty old. I want to be careful here because someone will say But I have one that works at 2 volts. :-) But that said there are any numbers of failures that will create the issue you could be seeing. There is a modulation signal typically in the 137 hz range and 274 Hz. There is the RF at 6.8 Ghz or so and lastly the rf that excites the RB lamp. Any of these things can be wrong and the system will not achieve lock. If its weak the lamp may glow but essentially run cool in color temperature. But at this point I can say there are indeed really great eperts on here that can give you better guidance. Regards Paul. WB8TSL On Thu, Dec 12, 2013 at 3:05 PM, Jamieson (Jim) Rowe jimr...@optusnet.com.au wrote: Hi, I’m an elderly time-nut newby, and I’ve already struck trouble with a used FE-5680 Rb-vapour reference I bought via eBay. It runs (from +16V and +5V), and the current drain starts at 1.75A and then drops over 5 minutes or so down to about 650mA. But it won’t lock, even if I leave it powered up for a few hours (with a fan to keep it from getting too hot). The output frequency just keeps switching up and down between about 850Hz and 1080Hz, with a bit of ‘lingering’ near each end. And of course the ‘lock’ output at pin 3 stays stubbornly at about 4.35V. To my newby brain, this sounds like the problem is either in the Rb lamp (too dark, perhaps), or else in the photodetector and buffer, etc, forming the ‘dip detector’ part of the feedback loop. Could one of you much-more-experienced time-nutters tell me if my diagnosis sounds right? Also, I’ve found a schematic for the digital sections of the FE-5680A in your archives, kindly drawn up by one of your very experienced members, but has anyone done a similar schematic for the ‘analog’ sections? I suspect I’m going to have to work out for myself where to test for a fault in these sections. There’s also a bit of a mystery (in my mind, at least) regarding that little 2-pin SIL header just near the Rb lamp, on the top of the PCB. Anyone know what that’s for? All the best in anticipation, folks. Jim Rowe ___ 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] Shortt Clock Recent Measurements
There is a good writeup of the Dicke switch in Horowitz Hill The Art of Electronics, since Horiwitz is a radioastronomer of note. I've just bought my daughter a copy for Xmas, poor girl, she wants to be an engineer... Tom Harris celephi...@gmail.com On 11 December 2013 13:02, Don Latham d...@montana.com wrote: Brooke Clarke PS When I was working in microwave electronics we talked about the Dicke radiometer, but I haven't found any definitive web page about that. Gotta look at Radio Astronomy pages and history. Actually, Dicke was using that radiometer to look for the microwave cosmic background, but the bell Labs guys had the big antenna. size matters :-) -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ 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] Shortt Clock Recent Measurements
:Hi Tom: I can't find anything in the Table of Contents or in the index. Can you tell me the page or title of the writeup? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Tom Harris wrote: There is a good writeup of the Dicke switch in Horowitz Hill The Art of Electronics, since Horiwitz is a radioastronomer of note. I've just bought my daughter a copy for Xmas, poor girl, she wants to be an engineer... Tom Harris celephi...@gmail.com On 11 December 2013 13:02, Don Latham d...@montana.com wrote: Brooke Clarke PS When I was working in microwave electronics we talked about the Dicke radiometer, but I haven't found any definitive web page about that. Gotta look at Radio Astronomy pages and history. Actually, Dicke was using that radiometer to look for the microwave cosmic background, but the bell Labs guys had the big antenna. size matters :-) -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ 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] Shortt Clock Recent Measurements
On 12/12/13 4:28 PM, Tom Harris wrote: The eccentric English physicist Boys made quartz fibres by attaching one end to a crossbow bolt, heating the middle and then firing the bolt, at what I have been unable to determine. He used this to measure the gravitational constant by suspending iron spheres from the resultant fibre, which of course was amazingly strong for it's diameter. Myself I'd use a pneumatic cannon, since I have one, rather than a crossbow. A crossbow is, shall we say, more English, although perhaps historically, a longbow might be more significant. Was that the same Boys who invented the Boys camera used to take lightning photographs? It's a sort of rotating drum streak camera. ___ 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] Shortt Clock Recent Measurements
It's in the section on lock in amplifiers I think. The switch has a clever 3 way action I think but I can't quire remember how it works. I do remember thinking how ingenious it was at the time, since I was designing lock in amplifiers for detecting optical absorbance over 10cm path lengths using photodiodes, instead of the tradional PMTs. Tom Harris celephi...@gmail.com On 13 December 2013 14:19, Brooke Clarke bro...@pacific.net wrote: :Hi Tom: I can't find anything in the Table of Contents or in the index. Can you tell me the page or title of the writeup? Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Tom Harris wrote: There is a good writeup of the Dicke switch in Horowitz Hill The Art of Electronics, since Horiwitz is a radioastronomer of note. I've just bought my daughter a copy for Xmas, poor girl, she wants to be an engineer... Tom Harris celephi...@gmail.com On 11 December 2013 13:02, Don Latham d...@montana.com wrote: Brooke Clarke PS When I was working in microwave electronics we talked about the Dicke radiometer, but I haven't found any definitive web page about that. Gotta look at Radio Astronomy pages and history. Actually, Dicke was using that radiometer to look for the microwave cosmic background, but the bell Labs guys had the big antenna. size matters :-) -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ 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] Shortt Clock Recent Measurements
Jim Lux The very one... Don Was that the same Boys who invented the Boys camera used to take lightning photographs? It's a sort of rotating drum streak camera. ___ 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. -- The power of accurate observation is commonly called cynicism by those who have not got it. -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ 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.
