Re: [time-nuts] Trak 8810 Station Clock
Chris Looked at the photos and believe you do not need a down converter. The one pix has a filter in it. dcf21r57. Its a murrata GPS bandpass filter 1575 MHz. So that indicates its looking for a antenna. See what voltage is on the antenna jack. On Sat, Jul 20, 2019 at 9:58 PM paul swed wrote: > Chris > What Bob was mentioning is true of the older units circa 1990s. I have > homebrewed down converters for two older units. Essentially everything gets > multiplexed onto the one jack so you can't really tell by looking if it > needs a downconverter or just an antenna. A bit of a hint. If there is > something like 12-15VDC on the jack then it needed a down converter. But > its just a hint not a rule. > Its funny how you find great receivers for $0 only to find out a key > component is missing. > Thats how I ended up with my Austron. > Good luck > Paul > WB8TSL > > On Sat, Jul 20, 2019 at 9:00 PM Chris Quayle wrote: > >> Hi >> >> > It’s a pretty good guess that a device from that era ran a >> “downconverter” head end. >> > They had a full RF front end out at the antenna and fed some sort of IF >> frequency >> > back to the unit. Various outfits had approaches to how to do it. The >> net result is that >> > the head end is pretty specific to this or that box (or at least series >> of boxes). >> > >> > Since it’s an entirely different approach to getting things done, >> directly replacing the >> > head end with a modern module is going to be tough. The normal >> alternative is to >> > build up a downconverter. Some do it from scratch, others find a >> similar unit >> > somewhere and modify it to do the job. The big trick is to find out >> exactly what the >> > main box is looking for …. >> > >> > Bob >> >> >> I had wondered about that, but if you look at the antenna input, it >> looks like pretty high frequency, with a track inductor. Would >> assume that a downconverter from gps frequency would >> translate to baseband, but may be wrong. >> >> Took a few pics of the board, in case it looks familiar to >> anyone, but it must have been used on other, perhaps marine or >> avionics kit of the time. Problem is finding such an item, say >> on Ebay, without taking the lid off to verify contents. Have a >> feeling this quest may take some time :-). >> >> Here are the pics anyway: >> >> https://www.flickr.com/photos/182770787@N05/ >> >> Regards, >> >> Chris >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Trak 8810 Station Clock
Chris What Bob was mentioning is true of the older units circa 1990s. I have homebrewed down converters for two older units. Essentially everything gets multiplexed onto the one jack so you can't really tell by looking if it needs a downconverter or just an antenna. A bit of a hint. If there is something like 12-15VDC on the jack then it needed a down converter. But its just a hint not a rule. Its funny how you find great receivers for $0 only to find out a key component is missing. Thats how I ended up with my Austron. Good luck Paul WB8TSL On Sat, Jul 20, 2019 at 9:00 PM Chris Quayle wrote: > Hi > > > It’s a pretty good guess that a device from that era ran a > “downconverter” head end. > > They had a full RF front end out at the antenna and fed some sort of IF > frequency > > back to the unit. Various outfits had approaches to how to do it. The > net result is that > > the head end is pretty specific to this or that box (or at least series > of boxes). > > > > Since it’s an entirely different approach to getting things done, > directly replacing the > > head end with a modern module is going to be tough. The normal > alternative is to > > build up a downconverter. Some do it from scratch, others find a similar > unit > > somewhere and modify it to do the job. The big trick is to find out > exactly what the > > main box is looking for …. > > > > Bob > > > I had wondered about that, but if you look at the antenna input, it > looks like pretty high frequency, with a track inductor. Would > assume that a downconverter from gps frequency would > translate to baseband, but may be wrong. > > Took a few pics of the board, in case it looks familiar to > anyone, but it must have been used on other, perhaps marine or > avionics kit of the time. Problem is finding such an item, say > on Ebay, without taking the lid off to verify contents. Have a > feeling this quest may take some time :-). > > Here are the pics anyway: > > https://www.flickr.com/photos/182770787@N05/ > > Regards, > > Chris > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] HP5370A vs B version
kb...@n1k.org said: [Context is 10811s.] > Because they are an un-sealed unit, power off storage is not kind to them. > Some take a long time to recover. A few never really seem to settle down. What's the mechanism? Lots of stuff ages faster when it is warm/hot. I'd guess humidity. What's the time scale? If 20 years of power off is nasty, is 1 year OK? 1 month? What have we learned about packaging since then? Would a similar design made with modern parts hold up better? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Timelab and GPIB, Aglient and Prologix adapter
The 82357B software has a 488.2 compatible mode. It should work. On Sat, Jul 20, 2019 at 1:08 PM Taka Kamiya via time-nuts < time-nuts@lists.febo.com> wrote: > I am in process of purchasing HP8370. My intent was to use it along with > TIMELAB via GPIB. > > Oddly enough, TIMELAB documentation mentions "National Instruments NI488.2 > compatible GPIB adapters", Prologix GPIB-USB and Prologix GPIB-Ethernet, > but NOT Agilent/HP/82357B. First, I thought GPIB was a standard protocol. > I do not understand why it has to be a couple of specific brand. Has > anyone tried this combination? (TIMELAB & Agilent GPIB) > > My "Agilent" 82357B from eBay is apparently a clone. According to folks > in business, most of 82357B is a clone. > > Secondly, since Prologix GPIB-USB is $149 straight from > http://www.prologix.biz, (is this a right source?) I don't mind buying > it. But am I going to run into similar issues with other software/hardware? > I am entirely new to GPIB. I can use some guidance, please. > --- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Timelab and GPIB, Aglient and Prologix adapter
time-nuts@lists.febo.com said: > Secondly, since Prologix GPIB-USB is $149 straight from http:// > www.prologix.biz, (is this a right source?) I don't mind buying it. But am > I going to run into similar issues with other software/hardware? I am > entirely new to GPIB. I can use some guidance, please. The problem isn't the GPIB side, but how the adapter connects to your system. If it's a PCI card, you need a driver. The prologic connects via a USB serial chip. It uses one of the popular chips so you probably won't have any problems with drivers. I don't know anything about Timelab. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Timelab and GPIB, Aglient and Prologix adapter
I am in process of purchasing HP8370. My intent was to use it along with TIMELAB via GPIB. Oddly enough, TIMELAB documentation mentions "National Instruments NI488.2 compatible GPIB adapters", Prologix GPIB-USB and Prologix GPIB-Ethernet, but NOT Agilent/HP/82357B. First, I thought GPIB was a standard protocol. I do not understand why it has to be a couple of specific brand. Has anyone tried this combination? (TIMELAB & Agilent GPIB) My "Agilent" 82357B from eBay is apparently a clone. According to folks in business, most of 82357B is a clone. Secondly, since Prologix GPIB-USB is $149 straight from http://www.prologix.biz, (is this a right source?) I don't mind buying it. But am I going to run into similar issues with other software/hardware? I am entirely new to GPIB. I can use some guidance, please. --- (Mr.) Taka Kamiya KB4EMF / ex JF2DKG ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] HP5370A vs B version
There were field upgrades from HP5370A to B, I believe offered through the HP field services operation. I have an A->B converted unit. I believe it has the original front end, but the “B” firmware. It has been a while since I opened it up. Sent from my iPhone > On Jul 20, 2019, at 10:35, Taka Kamiya via time-nuts > wrote: > > Thank you. > I really do not want to buy from eBay. So far, none showed up with zero > problems. There's always something. My intent is to lock it to house > standard which is a GPSDO. I have lots of 10811 here but I don't know when > they were made. All I know is they are all 10811-6011. You are right - > especially for an instrument like this, standard is extremely important. > > --- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > > >On Saturday, July 20, 2019, 11:02:19 AM EDT, Bob kb8tq > wrote: > > Hi > > If you are buying them on eBay, it is not at all clear which OCXO your A or B > will show up > with. The 10811’s get swapped back and forth with earlier units in a lot of > used gear. One > might *think* it’s a one way exchange, but I’ve seen it go both ways. > > If you lock the counter to an external standard, it really does not matter a > lot which OCXO > is in it. > > Bob > >> On Jul 20, 2019, at 4:21 AM, Frank Stellmach >> wrote: >> >> Hi Mr. Taka Kamiya, >> >> the B version has a 500MHz front end, copied from the HP5345A, with a >> matched pair of amplifier / Schmitt trigger hybrids. >> The A version has separate amplifier and Schmitt trigger ICs. >> >> There were also changes on the trigger circuit. >> >> Then the B version has a simplified µP board, has the OCXO (10811-60111), >> which is a must for absolute T.I. and frequency measurements. >> >> Maybe the firmware was also improved a bit, I think mainly concerning the >> GPIB steering of the trigger circuit. >> >> This T.I. counter is supposed to be superior over others of that era, >> because this special time interpolator was more linear. >> >> I really love mine, so I don't want to sell it. >> >> Frank >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] HP5370A vs B version
Am 20.07.19 um 10:21 schrieb Frank Stellmach: the B version has a 500MHz front end, copied from the HP5345A, with a matched pair of amplifier / Schmitt trigger hybrids. The A version has separate amplifier and Schmitt trigger ICs. There were also changes on the trigger circuit. Then the B version has a simplified µP board, has the OCXO (10811-60111), which is a must for absolute T.I. and frequency measurements. My 5370A came with a 10811-60111 time base. It also came with LOTS of intermittent contacts, but it was nearly for free, so I can't complain. I solved the contact problem by buying a SR620 that was still under cal. :-) Gerhard ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Trak 8810 Station Clock
Hi It’s a pretty good guess that a device from that era ran a “downconverter” head end. They had a full RF front end out at the antenna and fed some sort of IF frequency back to the unit. Various outfits had approaches to how to do it. The net result is that the head end is pretty specific to this or that box (or at least series of boxes). Since it’s an entirely different approach to getting things done, directly replacing the head end with a modern module is going to be tough. The normal alternative is to build up a downconverter. Some do it from scratch, others find a similar unit somewhere and modify it to do the job. The big trick is to find out exactly what the main box is looking for …. Bob > On Jul 20, 2019, at 12:30 PM, Chris Quayle wrote: > > Hi, > > Bought one of the above gps clocks at a radio rally last > Sunday. Looked ok on the outside, but severe corrosion > from a leaked backup battery inside. Cleaned all that up, > replaced some caps and a few other parts on the psu board > and now at least partially working. All the menus seem to > work, no signal or power failures, leds blinking 1pps on > the main board and all rear panel outputs seem ok. > > Problem is that the gps engine fails to initialise in post. > Can't find any reference for this model on the web. > Did find an 8820 manual, but that has a different mainboard > and the serial port command set doesn't work on the 8810, > though characters are echo'd. > > This looks like very early gps module and no info on the > web for it. Read one page that suggests that this module > might be similar to the Magnavox MX4200 and perhaps a > connection to Truetime ?, but no other info found. > > The board says "Magnavox GPS Engine", with a part number > label 900578-803-3. Data codes on the devices are 1990-1992, > so must be a very early model. Question is, are there any > later gps modules compatable with this device in terms of > command set, or perhaps a known working board for sale, or > a manual somewhere ?. There's a neat output board that takes > a 10 Mz input, to provide 4 of each 1, 5 and 10Mhz sine > wave outputs on the back panel, useful in itself, but it > would be good to have this working, to add to the collection. > > Thanks, > > Chris > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Trak 8810 Station Clock
Hi, Bought one of the above gps clocks at a radio rally last Sunday. Looked ok on the outside, but severe corrosion from a leaked backup battery inside. Cleaned all that up, replaced some caps and a few other parts on the psu board and now at least partially working. All the menus seem to work, no signal or power failures, leds blinking 1pps on the main board and all rear panel outputs seem ok. Problem is that the gps engine fails to initialise in post. Can't find any reference for this model on the web. Did find an 8820 manual, but that has a different mainboard and the serial port command set doesn't work on the 8810, though characters are echo'd. This looks like very early gps module and no info on the web for it. Read one page that suggests that this module might be similar to the Magnavox MX4200 and perhaps a connection to Truetime ?, but no other info found. The board says "Magnavox GPS Engine", with a part number label 900578-803-3. Data codes on the devices are 1990-1992, so must be a very early model. Question is, are there any later gps modules compatable with this device in terms of command set, or perhaps a known working board for sale, or a manual somewhere ?. There's a neat output board that takes a 10 Mz input, to provide 4 of each 1, 5 and 10Mhz sine wave outputs on the back panel, useful in itself, but it would be good to have this working, to add to the collection. Thanks, Chris ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] HP5370A vs B version
Hi If you have a pile of 10811’s a fun experiment is to put them on power for a couple months. Log the frequency once a day or so and watch how they “drift in” to whatever the final frequency is. Because they are an un-sealed unit, power off storage is not kind to them. Some take a long time to recover. A few never really seem to settle down. Since the ones that don’t settle are not of a lot of use, they often head off to eBay and get passed from hand to hand over the years. In some cases you *can* find a problem component. There aren’t a lot of people who dig that deep *and* get it right. Bob > On Jul 20, 2019, at 11:35 AM, Taka Kamiya via time-nuts > wrote: > > Thank you. > I really do not want to buy from eBay. So far, none showed up with zero > problems. There's always something. My intent is to lock it to house > standard which is a GPSDO. I have lots of 10811 here but I don't know when > they were made. All I know is they are all 10811-6011. You are right - > especially for an instrument like this, standard is extremely important. > > --- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > > >On Saturday, July 20, 2019, 11:02:19 AM EDT, Bob kb8tq > wrote: > > Hi > > If you are buying them on eBay, it is not at all clear which OCXO your A or B > will show up > with. The 10811’s get swapped back and forth with earlier units in a lot of > used gear. One > might *think* it’s a one way exchange, but I’ve seen it go both ways. > > If you lock the counter to an external standard, it really does not matter a > lot which OCXO > is in it. > > Bob > >> On Jul 20, 2019, at 4:21 AM, Frank Stellmach >> wrote: >> >> Hi Mr. Taka Kamiya, >> >> the B version has a 500MHz front end, copied from the HP5345A, with a >> matched pair of amplifier / Schmitt trigger hybrids. >> The A version has separate amplifier and Schmitt trigger ICs. >> >> There were also changes on the trigger circuit. >> >> Then the B version has a simplified µP board, has the OCXO (10811-60111), >> which is a must for absolute T.I. and frequency measurements. >> >> Maybe the firmware was also improved a bit, I think mainly concerning the >> GPIB steering of the trigger circuit. >> >> This T.I. counter is supposed to be superior over others of that era, >> because this special time interpolator was more linear. >> >> I really love mine, so I don't want to sell it. >> >> Frank >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] HP5370A vs B version
Thank you. I really do not want to buy from eBay. So far, none showed up with zero problems. There's always something. My intent is to lock it to house standard which is a GPSDO. I have lots of 10811 here but I don't know when they were made. All I know is they are all 10811-6011. You are right - especially for an instrument like this, standard is extremely important. --- (Mr.) Taka Kamiya KB4EMF / ex JF2DKG On Saturday, July 20, 2019, 11:02:19 AM EDT, Bob kb8tq wrote: Hi If you are buying them on eBay, it is not at all clear which OCXO your A or B will show up with. The 10811’s get swapped back and forth with earlier units in a lot of used gear. One might *think* it’s a one way exchange, but I’ve seen it go both ways. If you lock the counter to an external standard, it really does not matter a lot which OCXO is in it. Bob > On Jul 20, 2019, at 4:21 AM, Frank Stellmach > wrote: > > Hi Mr. Taka Kamiya, > > the B version has a 500MHz front end, copied from the HP5345A, with a matched > pair of amplifier / Schmitt trigger hybrids. > The A version has separate amplifier and Schmitt trigger ICs. > > There were also changes on the trigger circuit. > > Then the B version has a simplified µP board, has the OCXO (10811-60111), > which is a must for absolute T.I. and frequency measurements. > > Maybe the firmware was also improved a bit, I think mainly concerning the > GPIB steering of the trigger circuit. > > This T.I. counter is supposed to be superior over others of that era, because > this special time interpolator was more linear. > > I really love mine, so I don't want to sell it. > > Frank > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
All: I think the leap-second correction is real important, or you have to change references. The whole (original) point of time is all about Sun time. What time to get up? When is noon? What is my longitude? But, the Earth is slowing down. According to Wikipedia, the Earth's rotation is slowing at the rate of 2.3 ms per day, per century. Or, Donald's super accurate free running clock is going to be off by about 42 seconds, relative to Sun time, after a century. (Assuming linear change for simplified calculations.) That means the accuracy of the Earth's rotation is only about 1.3 in 10E-8. (and slowing down.) Lots of leap-seconds on the way. Bezos' 1 year clock continuously sets/resets itself to Sun time. --- Graham == On Sat, Jul 20, 2019 at 2:00 AM donald collie wrote: > ...and speaking of electrolytic capacitors and reliability : I own a Rohde > & Schwarz POLYSCOP made in 1965 which has a 1000uF capacitor in the LV psu > that is still functioning well after 54 years. Mind you it`s a physically > large item compared to todays capacitors. > > Cheers!...Donald > C. > > On Sat, Jul 20, 2019 at 10:20 AM donald collie > wrote: > > > Thanks to all who replied! It looks like the antioxidants will win and > the > > clock will fail before the 100 years are up. Assuming the "accuracy" of > the > > GPSDO is 1 part in 10^12 then the inaccuracy after 100 years will be up > to > > : 60x60x24x365.25x100x1x10^-12= 3ms [approximately] - which is probably > > good enough for an old fella. I have to admit that I have an ulterior > > motive for asking this question : I wanted to know what sort of long term > > accuracy I could expect from the GPS constellation - looks as if 1 part > in > > 10 to the 12th is about right. > > > Cheers!...Donald > > C. > > > > On Sat, Jul 20, 2019 at 7:01 AM Bob kb8tq wrote: > > > >> Hi > >> > >> The simple answer is that your clock is locked directly to a set of time > >> sources built > >> into the GPS satellites. Those sources are corrected by ground stations > >> via comparison > >> to NRL and NIST (and indirectly other sources as well). The various > >> ground reference > >> time systems get measured and evaluated to form what we call the right > >> time. This > >> is done by BIH in Paris. That process also keeps NRL and NIST “in sync” > >> with the correct time. > >> > >> Since everything is locked together, there really isn’t any long term > >> drift. As long as > >> everything is functioning (and the PPS is from GPS not some random > >> divider) you > >> should be “on time” to within 100 ns pretty much forever. The time > >> involved could > >> be GPS time or UTC depending on how you associate time stamps with your > >> PPS edges. > >> > >> If indeed something goes wrong with GPS ( as unfortunately happened to > >> Galileo > >> very recently), your time could be just about anything if the error is > >> undetected. If > >> it is detected, your will go into holdover. The drift then depends very > >> much on just > >> what “Trimble” you have inside your setup. 10 us a day for the first day > >> is not an > >> uncommon number to see. Since it’s really frequency drift rather than > >> time drift, > >> the second day will be worse and it just goes downhill from there. > >> > >> If your PPS *is* from some random divider off of (say) 10 MHz, then > every > >> time power > >> goes out, it will come back up at a random point in the second. If you > >> punch > >> a button to “sync” it, you will only be able to move it in 100 ns steps > ( > >> the period > >> of 10 MHz). If the 10 MHz edge is “right on” with GPS that’s fine. If > >> it’s off by some > >> random amount ….. not so fine. > >> > >> This gets into a vary basic gotcha: A typical GPSDO *does* get the > output > >> PPS from > >> the 10 MHz. The PPS output direct from a GPS module probably is closer > to > >> “on time” > >> that the GPS PPS. It will bounce around a lot more, but it likely is > >> closer to being correct. > >> > >> Lots of twists and turns …... > >> > >> Bob > >> > >> > On Jul 19, 2019, at 1:17 AM, donald collie > >> wrote: > >> > > >> > Without wanting to show my ignorance by confusing accuracy, and > >> precision, > >> > etc, would some kind person please answer the following : Let me > >> explain - > >> > I have my prototype GPS diciplined [ Trimble inside] standard > frequency > >> > source connected to both a divide by 5,2,5 and 2 producing all the > >> > reference frequencies necessary for the various bits of equipment in > my > >> > workshop, AND the 1pps > >> > output connected to a 7474 "T" flipflop and thence via a 100uF > >> capacitor to > >> > a modified $10 analogue wall clock. Can anybody tell me this : If I > live > >> > another 100 years
Re: [time-nuts] HP5370A vs B version
Hi If you are buying them on eBay, it is not at all clear which OCXO your A or B will show up with. The 10811’s get swapped back and forth with earlier units in a lot of used gear. One might *think* it’s a one way exchange, but I’ve seen it go both ways. If you lock the counter to an external standard, it really does not matter a lot which OCXO is in it. Bob > On Jul 20, 2019, at 4:21 AM, Frank Stellmach > wrote: > > Hi Mr. Taka Kamiya, > > the B version has a 500MHz front end, copied from the HP5345A, with a matched > pair of amplifier / Schmitt trigger hybrids. > The A version has separate amplifier and Schmitt trigger ICs. > > There were also changes on the trigger circuit. > > Then the B version has a simplified µP board, has the OCXO (10811-60111), > which is a must for absolute T.I. and frequency measurements. > > Maybe the firmware was also improved a bit, I think mainly concerning the > GPIB steering of the trigger circuit. > > This T.I. counter is supposed to be superior over others of that era, because > this special time interpolator was more linear. > > I really love mine, so I don't want to sell it. > > Frank > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5370A vs B version
Hi Mr. Taka Kamiya, the B version has a 500MHz front end, copied from the HP5345A, with a matched pair of amplifier / Schmitt trigger hybrids. The A version has separate amplifier and Schmitt trigger ICs. There were also changes on the trigger circuit. Then the B version has a simplified µP board, has the OCXO (10811-60111), which is a must for absolute T.I. and frequency measurements. Maybe the firmware was also improved a bit, I think mainly concerning the GPIB steering of the trigger circuit. This T.I. counter is supposed to be superior over others of that era, because this special time interpolator was more linear. I really love mine, so I don't want to sell it. Frank ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
...and speaking of electrolytic capacitors and reliability : I own a Rohde & Schwarz POLYSCOP made in 1965 which has a 1000uF capacitor in the LV psu that is still functioning well after 54 years. Mind you it`s a physically large item compared to todays capacitors. Cheers!...Donald C. On Sat, Jul 20, 2019 at 10:20 AM donald collie wrote: > Thanks to all who replied! It looks like the antioxidants will win and the > clock will fail before the 100 years are up. Assuming the "accuracy" of the > GPSDO is 1 part in 10^12 then the inaccuracy after 100 years will be up to > : 60x60x24x365.25x100x1x10^-12= 3ms [approximately] - which is probably > good enough for an old fella. I have to admit that I have an ulterior > motive for asking this question : I wanted to know what sort of long term > accuracy I could expect from the GPS constellation - looks as if 1 part in > 10 to the 12th is about right. > Cheers!...Donald > C. > > On Sat, Jul 20, 2019 at 7:01 AM Bob kb8tq wrote: > >> Hi >> >> The simple answer is that your clock is locked directly to a set of time >> sources built >> into the GPS satellites. Those sources are corrected by ground stations >> via comparison >> to NRL and NIST (and indirectly other sources as well). The various >> ground reference >> time systems get measured and evaluated to form what we call the right >> time. This >> is done by BIH in Paris. That process also keeps NRL and NIST “in sync” >> with the correct time. >> >> Since everything is locked together, there really isn’t any long term >> drift. As long as >> everything is functioning (and the PPS is from GPS not some random >> divider) you >> should be “on time” to within 100 ns pretty much forever. The time >> involved could >> be GPS time or UTC depending on how you associate time stamps with your >> PPS edges. >> >> If indeed something goes wrong with GPS ( as unfortunately happened to >> Galileo >> very recently), your time could be just about anything if the error is >> undetected. If >> it is detected, your will go into holdover. The drift then depends very >> much on just >> what “Trimble” you have inside your setup. 10 us a day for the first day >> is not an >> uncommon number to see. Since it’s really frequency drift rather than >> time drift, >> the second day will be worse and it just goes downhill from there. >> >> If your PPS *is* from some random divider off of (say) 10 MHz, then every >> time power >> goes out, it will come back up at a random point in the second. If you >> punch >> a button to “sync” it, you will only be able to move it in 100 ns steps ( >> the period >> of 10 MHz). If the 10 MHz edge is “right on” with GPS that’s fine. If >> it’s off by some >> random amount ….. not so fine. >> >> This gets into a vary basic gotcha: A typical GPSDO *does* get the output >> PPS from >> the 10 MHz. The PPS output direct from a GPS module probably is closer to >> “on time” >> that the GPS PPS. It will bounce around a lot more, but it likely is >> closer to being correct. >> >> Lots of twists and turns …... >> >> Bob >> >> > On Jul 19, 2019, at 1:17 AM, donald collie >> wrote: >> > >> > Without wanting to show my ignorance by confusing accuracy, and >> precision, >> > etc, would some kind person please answer the following : Let me >> explain - >> > I have my prototype GPS diciplined [ Trimble inside] standard frequency >> > source connected to both a divide by 5,2,5 and 2 producing all the >> > reference frequencies necessary for the various bits of equipment in my >> > workshop, AND the 1pps >> > output connected to a 7474 "T" flipflop and thence via a 100uF >> capacitor to >> > a modified $10 analogue wall clock. Can anybody tell me this : If I live >> > another 100 years [Let`s say I take antioxidants ;-) ] what sort of >> error >> > should I expect in this clock? [I know that it`s better than 1 second >> per >> > day] >> > ___ >> > time-nuts mailing list -- time-nuts@lists.febo.com >> > To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> > and follow the instructions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
