Re: [time-nuts] Repairs and mods underway on HP 3586b
Tisha, Magnus encouraged me to share my "Happy Easter" with you, or at least this demo that's kinda like an easter egg: https://www.youtube.com/watch?v=8MZpnVs6CWc Enjoy, all. On Sun, Apr 1, 2018 at 8:24 PM, Tisha Hayes wrote: > Thanks to those who responded to my requests off-list for details on > correcting a partially functional HP 3586b. Here is where I am at with it; > > Replaced the incandescent lamp inside of the 5060-0329 rotary encoder for a > white LED with a resistor to work at 5VDC. > Ordered a 75 ohm BNC chassis jack > Installed two BNC-SMB cables for the 50 MHz connections that are normally > covered with blank plugs on the back panel > Removed all of the buttons and soaked them for a few hours in a mixture of > hydrogen peroxide and oxy-clean to remove the brownish oxidation > (in the process) of pulling the little wafer springs out of each switch and > rotating the metal around 180 degrees so the buttons do not need to make a > hard "click" > replaced the NiCad battery with an NiMH > > The unit already had the 10 MHz precision oscillator module (thanks to > Perry Sandeen for that). > > I have a couple of Rb standards that are already used for metrology > (spec-an's, tracking generators, R-590 and a couple of other receivers). I > will probably stick with those as frequency references as they are usually > running for days at a time. > > *Ms. Tisha Hayes, AA4HA* > ___ > 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] quartz / liquid nitrogen
Very true Sent from my iPhone > On Apr 3, 2018, at 7:51 PM, Bob kb8tq wrote: > > Hi > > If the objective is great phase noise far removed from carrier, there’s a > gotcha. > > Let’s say you have a 10 dbm source at room and it’s broadband is at KTB of > -174 + 1db. > That gives you -183 dbc. You cool your oscillator to whatever and KTB goes > down > to -194. You do a bang up job at that temperature and get within a db there > was well. > You now have a 10 dbm source with -203 dbc. > > Run the super cooled signal through a coax out to the room environment. Pass > it through > a 50 ohm gizmo and …. KTB is back at -174. Your source is at -184 dbc. To > *use* the > signal, you likely need to cool whatever it’s driving as well. > > While one might say …. that pretty weird. Well, similar things do happen. > Many an ultra > low phase noise OCXO gets sold, only to find that the “next stage” isn’t as > quiet as the > system guys hand hoped. Hmmm …. e ….oops !! > > Bob > >> On Apr 3, 2018, at 5:29 AM, Dana Whitlow wrote: >> >> Many years ago, circa 1977, I was moved to try some crude tests on a few >> semiconductor devices at LN2 temperature (77K). >> >> These tests were very crude, involving dunking the parts into the LN2 bath, >> and >> many failed outright. Most of the devices tested were in plastic packages. >> >> Here are the results as I remember them, applicable only for the survivors: >> >> Silicon bipolar transistors: The DC beta fell to very low values. >> Junction >> forward voltages rose considerably. >> >> Silicon JFETs: Seemed to continue working reasonably well. >> >> Silicon MOSFETs: Same as JFETs >> >> Red LEDs: The junction forward voltages rose considerably, to about 5V as >> I recall. The light output per unit current rose truly spectacularly. >> >> My first experiences with seriously-cryogenic RF amplifiers were at the >> Arecibo Observatory beginning about 11 years ago. These were all either >> GaAs- or InP-based and we cooled them to ~15K, generally leading to >> input-referred amplifier noise temperatures of ~3K. Many of the devices >> needed continuous exposure to light to work properly when cold, and the >> metal block amplifier packages had holes in the lid directly over the active >> device chips. Small red LEDs in ordinary plastic packages were inserted >> in the holes and were driven at a few mA, generally in a series string. >> Since cool-down was fairly gradual over a span of at least a couple hours, >> there was little problem with thermal shock and almost all LEDs survived >> cooldown and warmup for the several cycles they experienced during >> my 10 years at the observatory. >> >> RF amplifier biasing was invariably done with opamp circuits to maintain >> set drain currents and drain voltages, with said bias control circuits >> outside >> the dewar at room ambient temperature. Failures were not too uncommon, >> largely attributed to connector misbehavior at low temperature. Formation >> of "ice" (really frozen air) inside the dewars was suspected because fine >> wires >> inside the dewar were often found to have fairly sharp bends at improbable >> locations upon warmup for diagnostic purposes (or due to cooling system >> failure). >> >> Cooling was done with a closed-cycle gaseous He system, using the >> Gifford-McMahon cycle. Note that He does not liquefy (at reasonable >> pressures) until around 4K. All dewars for this kind of work depend on >> high vacuum inside for thermal insulation, with black body radiation >> and direct conduction through wires and mounting structures being >> the principal remaining heat leaks. >> >> At these temperatures, maintenance of high vacuum inside the dewar was >> essentially automatic because all components of the inward-leaking air >> were known to freeze out. This could lead to a hazard because over time, >> months or years, enough air could freeze out to result in dangerously high >> internal pressures upon "thawing" when the dewar was warmed for any >> reason. For this reason, all dewars were equipped with blowout plugs >> to avoid high pressure's damaging the dewars themselves. >> >> Dana >> >> >>> On Tue, Apr 3, 2018 at 12:26 AM, Mark Sims wrote: >>> >>> And you want your semiconductors to be in ceramic/lided packages with the >>> bond wires flapping in free air. Bond wires embedded in epoxy like to >>> break... don't ask how I found this out ;-) ... it brings back bad >>> memories... and makes bad memories... Quantum chips have very >>> elaborate/specialized bonding to survive liquid helium... even with that, >>> thermal cycling still breaks them. >>> ___ >>> 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
Re: [time-nuts] Harrison's birthday
Jim, The Harrison google doodle is attached for those that missed it [1]. A couple of comments: 1) One alert reader pointed out that the clocks are stopped. Google is capable of clever JavaScript animations, so the least they could do is have the clocks in motion. It would be especially interesting to see the famous "grasshopper escapement" in action. Well, there's youtube for that. 2) It might even be useful if the animation showed the clocks with the correct time. UTC at a minimum. Or local time, since google likely has a good idea what timezone you are in. 3) The artist followed the clock face marketing trick of using ~10 minutes after 10 o'clock. That creates symmetry between the hour hand about -60 degrees (left of center) and the minute hand about +60 degrees (right of center). Some of you realize that the hour hand is exactly -60 degrees only at 10:00, but by the time the minute hand gets to +60 degrees the time is now 10:10. And by then, the hour hand has moved further clockwise (yes, it's the one time when using that adjective is redundant) to -55 degrees so you now have overshot the magic moment when the two hands are truly in symmetry. You can google the math puzzle of when exactly after 10 o'clock the hands are in pure symmetry [2]. The magic moment occurs at +/- 55.385 degrees which is 10:09:14 AM/PM. If you want it to the nanosecond, then 10:09:13.846153846 is your answer. And this happens twice a day so even if you miss it, you get more chances. 4) Now that you know all of this, look again at the google cartoon. Note that neither the hour hand nor the minute hand is correct. The hour hand is a but too far ahead for 10:09, and the minute hand is a bit too far behind for 10:09. You just can't trust the internet anymore... /tvb [1] Doodles: https://www.google.com/doodles/john-harrisons-325th-birthday https://www.google.com/doodles?hl=en-GB https://www.theverge.com/2018/4/3/17190940/john-harrison-google-doodle-clock-sea-watch-longitude-marine-chronometer [2] Math clock puzzles: https://www.fq.math.ca/Scanned/21-2/monzingo.pdf https://www.quora.com/At-what-time-are-the-hour-and-minute-hands-at-equal-distance-from-the-6-hour https://ldlewis.com/hospital_clock/document/Timely.encounter.abr.cmplt.pdf - Original Message - From: "jimlux" To: "Discussion of precise time and frequency measurement" Sent: Monday, April 02, 2018 9:19 PM Subject: [time-nuts] Harrison's birthday > Google reminds us that 3 April is Harrison's birthday.. > > https://en.wikipedia.org/wiki/John_Harrison > > Interesting he (depending on your calendar) was born and died on the > same day. And, interesting he died in 1776, which is of some > significance in the US. > ___ > 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] quartz / liquid nitrogen
Hi If the objective is great phase noise far removed from carrier, there’s a gotcha. Let’s say you have a 10 dbm source at room and it’s broadband is at KTB of -174 + 1db. That gives you -183 dbc. You cool your oscillator to whatever and KTB goes down to -194. You do a bang up job at that temperature and get within a db there was well. You now have a 10 dbm source with -203 dbc. Run the super cooled signal through a coax out to the room environment. Pass it through a 50 ohm gizmo and …. KTB is back at -174. Your source is at -184 dbc. To *use* the signal, you likely need to cool whatever it’s driving as well. While one might say …. that pretty weird. Well, similar things do happen. Many an ultra low phase noise OCXO gets sold, only to find that the “next stage” isn’t as quiet as the system guys hand hoped. Hmmm …. e ….oops !! Bob > On Apr 3, 2018, at 5:29 AM, Dana Whitlow wrote: > > Many years ago, circa 1977, I was moved to try some crude tests on a few > semiconductor devices at LN2 temperature (77K). > > These tests were very crude, involving dunking the parts into the LN2 bath, > and > many failed outright. Most of the devices tested were in plastic packages. > > Here are the results as I remember them, applicable only for the survivors: > > Silicon bipolar transistors: The DC beta fell to very low values. > Junction > forward voltages rose considerably. > > Silicon JFETs: Seemed to continue working reasonably well. > > Silicon MOSFETs: Same as JFETs > > Red LEDs: The junction forward voltages rose considerably, to about 5V as > I recall. The light output per unit current rose truly spectacularly. > > My first experiences with seriously-cryogenic RF amplifiers were at the > Arecibo Observatory beginning about 11 years ago. These were all either > GaAs- or InP-based and we cooled them to ~15K, generally leading to > input-referred amplifier noise temperatures of ~3K. Many of the devices > needed continuous exposure to light to work properly when cold, and the > metal block amplifier packages had holes in the lid directly over the active > device chips. Small red LEDs in ordinary plastic packages were inserted > in the holes and were driven at a few mA, generally in a series string. > Since cool-down was fairly gradual over a span of at least a couple hours, > there was little problem with thermal shock and almost all LEDs survived > cooldown and warmup for the several cycles they experienced during > my 10 years at the observatory. > > RF amplifier biasing was invariably done with opamp circuits to maintain > set drain currents and drain voltages, with said bias control circuits > outside > the dewar at room ambient temperature. Failures were not too uncommon, > largely attributed to connector misbehavior at low temperature. Formation > of "ice" (really frozen air) inside the dewars was suspected because fine > wires > inside the dewar were often found to have fairly sharp bends at improbable > locations upon warmup for diagnostic purposes (or due to cooling system > failure). > > Cooling was done with a closed-cycle gaseous He system, using the > Gifford-McMahon cycle. Note that He does not liquefy (at reasonable > pressures) until around 4K. All dewars for this kind of work depend on > high vacuum inside for thermal insulation, with black body radiation > and direct conduction through wires and mounting structures being > the principal remaining heat leaks. > > At these temperatures, maintenance of high vacuum inside the dewar was > essentially automatic because all components of the inward-leaking air > were known to freeze out. This could lead to a hazard because over time, > months or years, enough air could freeze out to result in dangerously high > internal pressures upon "thawing" when the dewar was warmed for any > reason. For this reason, all dewars were equipped with blowout plugs > to avoid high pressure's damaging the dewars themselves. > > Dana > > > On Tue, Apr 3, 2018 at 12:26 AM, Mark Sims wrote: > >> And you want your semiconductors to be in ceramic/lided packages with the >> bond wires flapping in free air. Bond wires embedded in epoxy like to >> break... don't ask how I found this out ;-) ... it brings back bad >> memories... and makes bad memories... Quantum chips have very >> elaborate/specialized bonding to survive liquid helium... even with that, >> thermal cycling still breaks them. >> ___ >> 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 unsubs
Re: [time-nuts] new longwave time service planned in India
Pieter That is quite a surprise that a country is setting up a long wave system these days. They still have to raise the money but it seems like a semi-private arrangement. Even more interesting is they suggest 3 locations. Something to try to find in the VLF bands some day in the future. Regards Paul WB8TSL On Tue, Apr 3, 2018 at 5:16 PM, Pieter-Tjerk de Boer wrote: > Hi, > > Apparently India plans to build two longwave transmitters for a national > time signal service: > http://www.thehindu.com/todays-paper/tp-national/coming-huge-towers-to- > publicise-right-time/article23377284.ece > > No technical details such as frequency and modulation are given, nor > whether > the carrier will also serve as a reference frequency. > > They do mention involvement of the German EFR company, who operate three > transmitters between 129 and 139 kHz for remotely controlling equipment > and broadcasting time, using 200 baud FSK. One might speculate similar > signals will be used for the new India service. > > Regards, > Pieter-Tjerk (PA3FWM) > > ___ > 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] Cheap jitter measurements
On the practical side, the 5345 is HEAVY due to its older technology—doing what it does with first-generation ICs required HP jam an enormous amount of circuitry into a fairly small physical package. Jeremy N6WFO On Tue, Apr 3, 2018 at 2:39 PM Bob kb8tq wrote: > Hi > > I would add the HP 5335 to the list of counters to look for. The surplus > market can be really > weird. A 5334 *should* be less than a 5335, but on any given day, that may > not be true. The > 5370 and 5345 are also worth looking for. Target price (at least for me) > wold be < $150 for a > quick buy and < $70 if I was willing to shop for a while. > > Getting data *out* of the older counters will involve GPIB. If you are not > already set up to do > that, there will be the cost of a cable and a simple adapter. > > If you want to move up a generation, the 53131 and 53132 are higher > resolution devices than > the 5334 and 5335. They give you the benefit of a serial port. No GPIB > stuff to bother with. > Finding one at price lower than the TAPR counter …. probably not. > > Bob > > > On Apr 3, 2018, at 3:04 PM, Tom Van Baak wrote: > > > > Hi Gary, > > > > One solution is to look for used hp, Fluke, or Racal time interval > counters on eBay. 1 or 2 ns is pretty easy to find with a $100 or $200 > budget. Look for Racal 1992 or hp 5334B as examples. If you plan to collect > lots of data, you'll want GPIB (or RS232 / USB) connections to a PC and > that will add to your net cost. > > > > Another solution is to homebrew your own 1 ns counter. The downside is > you will spend a month working out the bugs before you trust the data. Plus > if you don't already have another counter to compare it against it makes > development even harder. > > > > Third solution is the TICC from TAPR. It's new and works out of the box. > Lots of us use them. John did a very good job with the design. Highly > recommended. It's a dual-channel *time stamping* counter so you can collect > 1PPS data on two separate GPS receivers at the same time if you want. In > that respect it's 2x as useful as a commercial *time interval* counter. > > > > You mention jitter, not ADEV. I don't think you need a fancy timebase if > all you want to measure is jitter. You can get a good feel for the jitter > of a GPS / 1PPS output within a few samples. Even a minute of data is > usually enough to establish the rms jitter value. If you want a full ADEV > plot, then yes, you'd probably want at least an Rb for your reference. > > > > See paragraph "Timing Stability" at http://leapsecond.com/pages/MG1613S/ > for an example of what jitter from a GPS receiver looks like; in this case > it's primarily sawtooth. > > > > Right, the picPET has 400 ns resolution and so it is not the right tool > for your nanosecond needs. I do have a 10 ns version that I use, but that's > still a bit coarse for GPS work. > > > > I have spare FEI Rb here; I'll send it if you want it. That way you can > afford a TICC. > > > > /tvb > > > > > > - Original Message - > > From: "Gary E. Miller" > > To: "time-nuts" > > Sent: Tuesday, April 03, 2018 10:47 AM > > Subject: [time-nuts] Cheap jitter measurements > > > > > > Time-nuts! > > > > With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec > > resolution. That is the smallest increment of the RasPi 3B clock with > > a 64-bit kernel. That is clearly not time-nuts accuracy. > > > > What would you guys suggest as the cheapest way to see jitter down to > > around 1 nano second? > > > > I'm thinking maybe something like a rubidium standard (FE-5680A) and > > a TICC-TAPR? But that would put me out around $400. > > > > The picPET does not look accurate enough. Maybe a clever way to use it > > for more accuracy? Is there a picPET like thing cheaper than the > > TICC-TAPR? > > > > Ideas? > > > > RGDS > > GARY > > > --- > > Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 > > g...@rellim.com Tel:+1 541 382 8588 > > > >Veritas liberabit vos. -- Quid est veritas? > >"If you can’t measure it, you can’t improve it." - Lord Kelvin > > ___ > > 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. > -- Sent from my iPad 4. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bi
[time-nuts] Open day at the National Physical Laboratory (NPL) on Thursday 17 May 2018.
NPL opens their doors to the public once every 2 years. It is well worth going. Tickets are only 3.00 each, and that money is donated to a cancer charity. More details at http://www.npl.co.uk/open-house/ To make the most of it, you need to 1) Arrive early (14:00) 2) Leave when they close (20:00) 3) Walk around the many labs. Even 6 hours is not enough time to visit everything. I think you need to be reasonably fit, since it is not a place where you sit down in a chair and listen to lectures all day. I think NPL do a really good job, as they manage to put on something that is interesting to both children and professional scientists. Lots of schools have trips there for the day. Dave ___ 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] new longwave time service planned in India
Hi, Apparently India plans to build two longwave transmitters for a national time signal service: http://www.thehindu.com/todays-paper/tp-national/coming-huge-towers-to-publicise-right-time/article23377284.ece No technical details such as frequency and modulation are given, nor whether the carrier will also serve as a reference frequency. They do mention involvement of the German EFR company, who operate three transmitters between 129 and 139 kHz for remotely controlling equipment and broadcasting time, using 200 baud FSK. One might speculate similar signals will be used for the new India service. Regards, Pieter-Tjerk (PA3FWM) ___ 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] Cheap jitter measurements
Hi I would add the HP 5335 to the list of counters to look for. The surplus market can be really weird. A 5334 *should* be less than a 5335, but on any given day, that may not be true. The 5370 and 5345 are also worth looking for. Target price (at least for me) wold be < $150 for a quick buy and < $70 if I was willing to shop for a while. Getting data *out* of the older counters will involve GPIB. If you are not already set up to do that, there will be the cost of a cable and a simple adapter. If you want to move up a generation, the 53131 and 53132 are higher resolution devices than the 5334 and 5335. They give you the benefit of a serial port. No GPIB stuff to bother with. Finding one at price lower than the TAPR counter …. probably not. Bob > On Apr 3, 2018, at 3:04 PM, Tom Van Baak wrote: > > Hi Gary, > > One solution is to look for used hp, Fluke, or Racal time interval counters > on eBay. 1 or 2 ns is pretty easy to find with a $100 or $200 budget. Look > for Racal 1992 or hp 5334B as examples. If you plan to collect lots of data, > you'll want GPIB (or RS232 / USB) connections to a PC and that will add to > your net cost. > > Another solution is to homebrew your own 1 ns counter. The downside is you > will spend a month working out the bugs before you trust the data. Plus if > you don't already have another counter to compare it against it makes > development even harder. > > Third solution is the TICC from TAPR. It's new and works out of the box. Lots > of us use them. John did a very good job with the design. Highly recommended. > It's a dual-channel *time stamping* counter so you can collect 1PPS data on > two separate GPS receivers at the same time if you want. In that respect it's > 2x as useful as a commercial *time interval* counter. > > You mention jitter, not ADEV. I don't think you need a fancy timebase if all > you want to measure is jitter. You can get a good feel for the jitter of a > GPS / 1PPS output within a few samples. Even a minute of data is usually > enough to establish the rms jitter value. If you want a full ADEV plot, then > yes, you'd probably want at least an Rb for your reference. > > See paragraph "Timing Stability" at http://leapsecond.com/pages/MG1613S/ for > an example of what jitter from a GPS receiver looks like; in this case it's > primarily sawtooth. > > Right, the picPET has 400 ns resolution and so it is not the right tool for > your nanosecond needs. I do have a 10 ns version that I use, but that's still > a bit coarse for GPS work. > > I have spare FEI Rb here; I'll send it if you want it. That way you can > afford a TICC. > > /tvb > > > - Original Message - > From: "Gary E. Miller" > To: "time-nuts" > Sent: Tuesday, April 03, 2018 10:47 AM > Subject: [time-nuts] Cheap jitter measurements > > > Time-nuts! > > With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec > resolution. That is the smallest increment of the RasPi 3B clock with > a 64-bit kernel. That is clearly not time-nuts accuracy. > > What would you guys suggest as the cheapest way to see jitter down to > around 1 nano second? > > I'm thinking maybe something like a rubidium standard (FE-5680A) and > a TICC-TAPR? But that would put me out around $400. > > The picPET does not look accurate enough. Maybe a clever way to use it > for more accuracy? Is there a picPET like thing cheaper than the > TICC-TAPR? > > Ideas? > > RGDS > GARY > --- > Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 > g...@rellim.com Tel:+1 541 382 8588 > >Veritas liberabit vos. -- Quid est veritas? >"If you can’t measure it, you can’t improve it." - Lord Kelvin > ___ > 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] Cheap jitter measurements
Gary There is a Blast from the past the PIC TIC. Richard McCorkle did it and in its time was widely popular. He helped me on many projects so I included his boards with my board orders. Not being a time nut I never took a closer look at his board. Having recently revisited the subject for simple low cost monitoring of sources versus GPS and looking at Riley's comments found out that Richard used schematic capture, not what you want to use in timing applications. Did do a new board with ground plane. Also did a V drive with time chip for long term data recording using a USB stick. The unit is well documented. I have boards and you are welcomed to a set, can also help with key chips, only one SMD, we plan to build and test but lately have been distracted with a minor redo of the excellent Riley Dual Mixer and my 2 channel Ping Pong counter that Corby loves so much that he has three. Had some interface problems that had us going for weeks. When you chase 1 E-13 and 14 nothing comes easy. Again if interested contact me off list. Bert Kehren In a message dated 4/3/2018 2:35:18 PM Eastern Standard Time, g...@rellim.com writes: Time-nuts! With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec resolution. That is the smallest increment of the RasPi 3B clock with a 64-bit kernel. That is clearly not time-nuts accuracy. What would you guys suggest as the cheapest way to see jitter down to around 1 nano second? I'm thinking maybe something like a rubidium standard (FE-5680A) and a TICC-TAPR? But that would put me out around $400. The picPET does not look accurate enough. Maybe a clever way to use it for more accuracy? Is there a picPET like thing cheaper than the TICC-TAPR? Ideas? RGDS GARY --- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin ___ 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] Cheap jitter measurements
g...@rellim.com said: > With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec > resolution. That is the smallest increment of the RasPi 3B clock with a > 64-bit kernel. That is clearly not time-nuts accuracy. > What would you guys suggest as the cheapest way to see jitter down to around > 1 nano second? What do you mean by "jitter" and what do you really want to do? Jitter usually needs a reference. Do you have one? > I'm thinking maybe something like a rubidium standard (FE-5680A) and a > TICC-TAPR? But that would put me out around $400. Do you have a scope? The Rigol DS1102E is/was quite popular and is good for close to a ns. I got mine several years ago for $400. Looks like the going price is closer to $300 now. It's got a USB port. You can read the data and decode it in software. They make lots of similar scopes. The middle 2 digits are the bandwidth: 5=> 50MHz, 10=>100MHz. The last digit is the number of channels.) The chip in the BeagleBone series boards has extra CPUs that help with things like this. I don't know how fast they go. I haven't seen 64 bit versions or a lot of software activity. -- These are my opinions. I hate spam. ___ 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] Cheap jitter measurements
Hi Gary, One solution is to look for used hp, Fluke, or Racal time interval counters on eBay. 1 or 2 ns is pretty easy to find with a $100 or $200 budget. Look for Racal 1992 or hp 5334B as examples. If you plan to collect lots of data, you'll want GPIB (or RS232 / USB) connections to a PC and that will add to your net cost. Another solution is to homebrew your own 1 ns counter. The downside is you will spend a month working out the bugs before you trust the data. Plus if you don't already have another counter to compare it against it makes development even harder. Third solution is the TICC from TAPR. It's new and works out of the box. Lots of us use them. John did a very good job with the design. Highly recommended. It's a dual-channel *time stamping* counter so you can collect 1PPS data on two separate GPS receivers at the same time if you want. In that respect it's 2x as useful as a commercial *time interval* counter. You mention jitter, not ADEV. I don't think you need a fancy timebase if all you want to measure is jitter. You can get a good feel for the jitter of a GPS / 1PPS output within a few samples. Even a minute of data is usually enough to establish the rms jitter value. If you want a full ADEV plot, then yes, you'd probably want at least an Rb for your reference. See paragraph "Timing Stability" at http://leapsecond.com/pages/MG1613S/ for an example of what jitter from a GPS receiver looks like; in this case it's primarily sawtooth. Right, the picPET has 400 ns resolution and so it is not the right tool for your nanosecond needs. I do have a 10 ns version that I use, but that's still a bit coarse for GPS work. I have spare FEI Rb here; I'll send it if you want it. That way you can afford a TICC. /tvb - Original Message - From: "Gary E. Miller" To: "time-nuts" Sent: Tuesday, April 03, 2018 10:47 AM Subject: [time-nuts] Cheap jitter measurements Time-nuts! With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec resolution. That is the smallest increment of the RasPi 3B clock with a 64-bit kernel. That is clearly not time-nuts accuracy. What would you guys suggest as the cheapest way to see jitter down to around 1 nano second? I'm thinking maybe something like a rubidium standard (FE-5680A) and a TICC-TAPR? But that would put me out around $400. The picPET does not look accurate enough. Maybe a clever way to use it for more accuracy? Is there a picPET like thing cheaper than the TICC-TAPR? Ideas? RGDS GARY --- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin ___ 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] Cheap jitter measurements
Find a nice used 5370/5371? :) There is a 5371 on ebay for $250 at the moment. On Tue, Apr 3, 2018 at 1:47 PM, Gary E. Miller wrote: > Time-nuts! > > With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec > resolution. That is the smallest increment of the RasPi 3B clock with > a 64-bit kernel. That is clearly not time-nuts accuracy. > > What would you guys suggest as the cheapest way to see jitter down to > around 1 nano second? > > I'm thinking maybe something like a rubidium standard (FE-5680A) and > a TICC-TAPR? But that would put me out around $400. > > The picPET does not look accurate enough. Maybe a clever way to use it > for more accuracy? Is there a picPET like thing cheaper than the > TICC-TAPR? > > Ideas? > > RGDS > GARY > > --- > Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 > g...@rellim.com Tel:+1 541 382 8588 > > Veritas liberabit vos. -- Quid est veritas? > "If you can’t measure it, you can’t improve it." - Lord Kelvin > ___ > 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] Cheap jitter measurements
On Tue, 3 Apr 2018 10:47:37 -0700 "Gary E. Miller" wrote: > What would you guys suggest as the cheapest way to see jitter down to > around 1 nano second? Look at Nick Sayers GPSDO and his interpolator. You wont get any cheaper than that. Next best thing is to use a TDC7200 like in the TICC. Of course, you will need a standard that is stable enough on the time scales you are looking at. Which is for short taus (<100s) a good OCXO and for 1s to 10ks an Rb, and beyond that a Cs beam standard or hydrogen maser. Attila Kinali -- The bad part of Zurich is where the degenerates throw DARK chocolate at you. ___ 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] quartz / liquid nitrogen
Hi Mark: When Aetech started to make their own Tunnel Diodes there was a problem with the neck breaking. Note they were made by alloying a ball of metal onto a highly doped chip, bonding from the lip of the ceramic package to the ball then on to the opposite lip, then etching the chip away leaving something that in cross section looked like a mushroom. The neck was a few microns wide and often broke. The fix was to epoxy a glass rod on either side of the chip, between the metal bottom of the ceramic pill package and the bonding wire. The glass was chosen to have a CTE that matched the die. That solved the broken neck problem. http://prc68.com/I/Aertech.shtml#Prod -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Original Message And you want your semiconductors to be in ceramic/lided packages with the bond wires flapping in free air. Bond wires embedded in epoxy like to break... don't ask how I found this out ;-) ... it brings back bad memories... and makes bad memories... Quantum chips have very elaborate/specialized bonding to survive liquid helium... even with that, thermal cycling still breaks them. ___ 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] Cheap jitter measurements
Time-nuts! With care I can measure GPS jitter on a RasPi to a bit over 300 nano sec resolution. That is the smallest increment of the RasPi 3B clock with a 64-bit kernel. That is clearly not time-nuts accuracy. What would you guys suggest as the cheapest way to see jitter down to around 1 nano second? I'm thinking maybe something like a rubidium standard (FE-5680A) and a TICC-TAPR? But that would put me out around $400. The picPET does not look accurate enough. Maybe a clever way to use it for more accuracy? Is there a picPET like thing cheaper than the TICC-TAPR? Ideas? RGDS GARY --- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin ___ 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] Datum 1000B
Does anyone have any nuts and bolts (disassembly?) experience they can share regarding fixing a Datum 1000B pn 05818-115 (4x10MHz) which has a manual frequency pot and which will not adjust to 10,000,000.000 MHz? It will actually go as low as “10,000,000.2890”, but no lower. (The unit does not respond to EFC voltages.) Many thanks. Jim Robbins ___ 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] quartz / liquid nitrogen
Many years ago, circa 1977, I was moved to try some crude tests on a few semiconductor devices at LN2 temperature (77K). These tests were very crude, involving dunking the parts into the LN2 bath, and many failed outright. Most of the devices tested were in plastic packages. Here are the results as I remember them, applicable only for the survivors: Silicon bipolar transistors: The DC beta fell to very low values. Junction forward voltages rose considerably. Silicon JFETs: Seemed to continue working reasonably well. Silicon MOSFETs: Same as JFETs Red LEDs: The junction forward voltages rose considerably, to about 5V as I recall. The light output per unit current rose truly spectacularly. My first experiences with seriously-cryogenic RF amplifiers were at the Arecibo Observatory beginning about 11 years ago. These were all either GaAs- or InP-based and we cooled them to ~15K, generally leading to input-referred amplifier noise temperatures of ~3K. Many of the devices needed continuous exposure to light to work properly when cold, and the metal block amplifier packages had holes in the lid directly over the active device chips. Small red LEDs in ordinary plastic packages were inserted in the holes and were driven at a few mA, generally in a series string. Since cool-down was fairly gradual over a span of at least a couple hours, there was little problem with thermal shock and almost all LEDs survived cooldown and warmup for the several cycles they experienced during my 10 years at the observatory. RF amplifier biasing was invariably done with opamp circuits to maintain set drain currents and drain voltages, with said bias control circuits outside the dewar at room ambient temperature. Failures were not too uncommon, largely attributed to connector misbehavior at low temperature. Formation of "ice" (really frozen air) inside the dewars was suspected because fine wires inside the dewar were often found to have fairly sharp bends at improbable locations upon warmup for diagnostic purposes (or due to cooling system failure). Cooling was done with a closed-cycle gaseous He system, using the Gifford-McMahon cycle. Note that He does not liquefy (at reasonable pressures) until around 4K. All dewars for this kind of work depend on high vacuum inside for thermal insulation, with black body radiation and direct conduction through wires and mounting structures being the principal remaining heat leaks. At these temperatures, maintenance of high vacuum inside the dewar was essentially automatic because all components of the inward-leaking air were known to freeze out. This could lead to a hazard because over time, months or years, enough air could freeze out to result in dangerously high internal pressures upon "thawing" when the dewar was warmed for any reason. For this reason, all dewars were equipped with blowout plugs to avoid high pressure's damaging the dewars themselves. Dana On Tue, Apr 3, 2018 at 12:26 AM, Mark Sims wrote: > And you want your semiconductors to be in ceramic/lided packages with the > bond wires flapping in free air. Bond wires embedded in epoxy like to > break... don't ask how I found this out ;-) ... it brings back bad > memories... and makes bad memories... Quantum chips have very > elaborate/specialized bonding to survive liquid helium... even with that, > thermal cycling still breaks them. > ___ > 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] quartz / liquid nitrogen
Hi > On Apr 2, 2018, at 11:18 PM, jimlux wrote: > > On 4/2/18 1:39 PM, Hal Murray wrote: >>> If not Nitrogen, how about dry ice (-109F -78C)? >> Dry ice is relatively easy to get. It wouldn't be hard to try a quick >> experiment. > > > CTE mismatch in packages will be a significant problem - you might find that > your ICs don't work because bond wires have been ripped off the die. Parts > might have popped off the board too. > > But if you have one, and it's sacrificable, give it a try - a cooler with > some dry ice, and put the circuit above the dry ice, and it will cool slowly The first level solution is to forget about things like die coat and (gulp) die attach epoxy …. yes, this makes building things a bit insane. Bob > ___ > 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] TV Signals as a frequency reference
Yeah, that's pretty much the story around the country. I also have some monitoring software (monitoring PSIP, video and audio data, not specifically for monitoring STT packets) that I run on the Denver and Cheyenne stations 24 hours a day. Very few have set their GPS-UTC offset to 18 seconds. None are set to 0 though. The values range from 14 to 18. Almost half of the stations are within 1-2 seconds of the actual time (when taking their mostly wrong GPS-UTC offset into account). But some are 10's of seconds off, some are 10's of minutes off, and one is about an hour off, and another about 5 hours off (currently). The amazing thing is that every once in a while, some stations make a "correction". Sometimes it is to bring their error back down close to zero. But some appear to make large changes in the wrong direction, e.g. -88 seconds to -195 seconds. Looks like some stations have someone setting the time based on their watch (if I had to guess), which is really off. Doesn't give me much hope that the ATSC 3.0 standard will be implemented any better, given that the FCC has taken an even more hands off approach to this transition than the transition from analog to digital. I highly doubt we'll see many channels doing over the air 4K transmissions, i.e. they'll just use the better compression to stuff more crappy subchannels into their signal. But I'm getting pretty far away from time nuttery here, so I'll stop now. John On 4/2/2018 11:15 PM, Mark Sims wrote: Here's a local guy's take on monitoring time and DST errors on the stations in the Dallas area: http://home.earthlink.net/~schultdw/atsc/ ___ 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.
