[time-nuts] Portable standard
If I were to buy an HP 10811A OCXO to use as a portable, battery powered frequency standard, how would you recommend that it be powered and packaged? Assume that the final package would be powered 24/7 and sitting on a shelf most of the time. Prior to portable use, it would be checked against my GPSDO. Portable use would probably be at worse a few days, but more likely less than a day. I'm thinking of using a couple of 12V, 7AH SLA batteries and float charging them. Some charge circuits use pulsing current for SLA batteries. Would this affect the OCXO? Obviously too much air flow will be a problem. Can the OCXO, batteries and associated circuitry be sealed in a box with no vent holes (not strictly air tight)? What about putting the OCXO in a small styrofoam box by itself? Will that cause overheating or other issues? How about vent holes in the overall enclosure and baffles around the OCXO to minimize air flow? Should I forget the whole idea and just buy a rubidium? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Portable standard
In message BANLkTi=We=7+_yik4s1yhqat7zwu5ga...@mail.gmail.com, Joseph Gray wr ites: Some charge circuits use pulsing current for SLA batteries. Would this affect the OCXO? The only place where charge pulsing has shown an effect is where you have long strings of batteries (10+) where the pulses help equalize the charge by overcharging all the batteries, at a heavy cost in battery lifetime. A much better solution is electronic charge equalizers which does the same job without the cost of battery lifetime. A simple float-charger will do just fine for what you are trying to do. Obviously too much air flow will be a problem. Don't underestimate the thermal mass of the SLA batterieies, if you put them inside the insulation, you will have a much more stable temperature. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Portable standard
Joe, Before you worry about batteries and such, you first need to ask what it is that you are trying to accomplish. For instance, if you did not need the really close in low phase noise and really short term stability, then perhaps a Rubidium (Rb) oscillator would suit your needs. the Rb has better longer term stability than a crystal oscillator and can be left off until it is needed saving on battery requirements. A decent Rb would be up to specs in about 20 minutes and would suffice for most applications as a better general frequency reference for portable purposes. A really high quality crystal oscillator isn't worth a damn unless it is kept running constantly and without vibration. Any banging around is going to invalidate it. The Rb, unless you beat it with a hammer, does not suffer from those problems. Obviously you would like to treat either item with care, but things do happen and the Rb would be more rugged the crystal oscillator. BillWB6BNQ Joseph Gray wrote: If I were to buy an HP 10811A OCXO to use as a portable, battery powered frequency standard, how would you recommend that it be powered and packaged? Assume that the final package would be powered 24/7 and sitting on a shelf most of the time. Prior to portable use, it would be checked against my GPSDO. Portable use would probably be at worse a few days, but more likely less than a day. I'm thinking of using a couple of 12V, 7AH SLA batteries and float charging them. Some charge circuits use pulsing current for SLA batteries. Would this affect the OCXO? Obviously too much air flow will be a problem. Can the OCXO, batteries and associated circuitry be sealed in a box with no vent holes (not strictly air tight)? What about putting the OCXO in a small styrofoam box by itself? Will that cause overheating or other issues? How about vent holes in the overall enclosure and baffles around the OCXO to minimize air flow? Should I forget the whole idea and just buy a rubidium? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Portable standard
Joe Having OCXO's, Rb's, Tbolt's and a Cs running with battery backup, over time I have used AGM, Ni-CAD, and now Ni-MH,, in all cases you have to have ventilation. Also battery and electronics have to be separated as much as possible since temperature is enemy #1 for any battery. Today most electronic charge circuits use pulse mode and the cell voltage goes as high as 1.8 Volt. In addition the battery has to be electronically separate from the user since having the Osc. connected directly to the battery will mess up the charge controller. I have a fast switch over that also cuts out the battery to prevent total discharge. If you are interested contact me directly. I recently ordered a Li-Ion 12 V 9.5 A pack, ebay # 140512699149, have not received it yet, but look forward testing it, to do the same with Ni-MH would cost three times as much and weight and size would be at least twice. Once tested I will share the results. I agree with the comment on using a Rb since there is no cost differential, just make sure that it has active or passive heat transfer to make sure that the batteries run as cool as possible. Bert Kehren Miami In a message dated 4/6/2011 3:14:06 A.M. Eastern Daylight Time, jg...@zianet.com writes: If I were to buy an HP 10811A OCXO to use as a portable, battery powered frequency standard, how would you recommend that it be powered and packaged? Assume that the final package would be powered 24/7 and sitting on a shelf most of the time. Prior to portable use, it would be checked against my GPSDO. Portable use would probably be at worse a few days, but more likely less than a day. I'm thinking of using a couple of 12V, 7AH SLA batteries and float charging them. Some charge circuits use pulsing current for SLA batteries. Would this affect the OCXO? Obviously too much air flow will be a problem. Can the OCXO, batteries and associated circuitry be sealed in a box with no vent holes (not strictly air tight)? What about putting the OCXO in a small styrofoam box by itself? Will that cause overheating or other issues? How about vent holes in the overall enclosure and baffles around the OCXO to minimize air flow? Should I forget the whole idea and just buy a rubidium? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Portable standard
In message 1c9ce.62e32c26.3acda...@aol.com, ewkeh...@aol.com writes: Today most electronic charge circuits use pulse mode [...] Really ? The only place I see pulse mode chargers for SLA batteries is in the automobile snakeoil market, where d00des appearantly think it will make their speakers louder... For Li+ batteries in tiny gadgets, like mobiles, pulse mode charging is used to reduce the size and heat from the charge regulator, but it does nothing good for the battery. A good temperature compensating switchmode charger is the way to go. Poul-Henning PS: Source of good papers about batteries in backup applications: http://www.battcon.com/ArchivePapers.htm -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Tissot wrist watch
Dear Time-Nuts, I am afraid of being off topic with the following. If so, I sincerely apologize. I would like to know the precision to be expected on time keeping from a Tissot mod. J378/478 S wrist watch and how could be verified the fulfilment of that specification without waiting for a long time (probably more than one month) to observe an error of one second. Instructions on how to build a test basket or similar layout would be most appreciated. Thanks in advance, Antonio CT1TE ___ 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] SI Unit Problems
It makes senses even for this list! Numbers like 12 and 60 are chosen for their high number of dividers. That is a mathematical reason. Think of in ancient time all was divided in equal integers units. Even the Maya knew it! This is connected to numbers of low n-divide with the ultimate of prime numbers. If you're there you find reasons for encryption and low-spur PLLs. Then you're on on-topic again ;-) - Henry -- ehydra.dyndns.info ___ 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] Portable standard
Sorry to confuse. Pulse was the wrong word. What I was trying to say is that during the charge mode the charge controller does interrupt the charge process to check battery voltage. Since English is my third language please forgive me. Bert Kehren In a message dated 4/6/2011 7:04:36 A.M. Eastern Daylight Time, p...@phk.freebsd.dk writes: In message 1c9ce.62e32c26.3acda...@aol.com, ewkeh...@aol.com writes: Today most electronic charge circuits use pulse mode [...] Really ? The only place I see pulse mode chargers for SLA batteries is in the automobile snakeoil market, where d00des appearantly think it will make their speakers louder... For Li+ batteries in tiny gadgets, like mobiles, pulse mode charging is used to reduce the size and heat from the charge regulator, but it does nothing good for the battery. A good temperature compensating switchmode charger is the way to go. Poul-Henning PS: Source of good papers about batteries in backup applications: http://www.battcon.com/ArchivePapers.htm -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Portable standard
The HP105B might meet you needs if you can live with a 5mhz output. The packaging and DC power issues have been taken care of and adjusting the frequency is eaiser IMHO. - Original Message From: Joseph Gray jg...@zianet.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wed, April 6, 2011 12:13:37 AM Subject: [time-nuts] Portable standard If I were to buy an HP 10811A OCXO to use as a portable, battery powered frequency standard, how would you recommend that it be powered and packaged? Assume that the final package would be powered 24/7 and sitting on a shelf most of the time. Prior to portable use, it would be checked against my GPSDO. Portable use would probably be at worse a few days, but more likely less than a day. I'm thinking of using a couple of 12V, 7AH SLA batteries and float charging them. Some charge circuits use pulsing current for SLA batteries. Would this affect the OCXO? Obviously too much air flow will be a problem. Can the OCXO, batteries and associated circuitry be sealed in a box with no vent holes (not strictly air tight)? What about putting the OCXO in a small styrofoam box by itself? Will that cause overheating or other issues? How about vent holes in the overall enclosure and baffles around the OCXO to minimize air flow? Should I forget the whole idea and just buy a rubidium? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] SI Unit Problems
On 4/5/11 7:38 PM, Greg Broburg wrote: The number 6 and derivations thereof were presented to the world of science from the numerologists. Time was arranged as parts of a day, 24 hours 60 minutes per hour 60 seconds per minute. Very tenuous at best. I propose that we consider 100 seconds in a minute, 100 minutes in an hour, and 10 hours in a day. People could handle that with an IPhone ap, right? Then there's the Babylonians, who used a number system where 60 was important. 60 has lots of factors, which makes dividing things up into equal sized chunks easy. (as my daughter said when much younger, and doing fractions in math, curse those Babylonians). The fact that a year is about 360 days long (6*60) also feeds into it. You really needed the invention and adoption of place value for a decimalized system to work well, and that didn't come along til around 700-800 C.E., I think. By then, the fractional measurement approach and customary units were well entrenched. Sure, although King John standardized the yard and inch and pound and such in the 1200s, I'm sure that the units themselves were already in use for a long time. Currency is also done in a fractional system (pieces o'eight, 12pence/shilling with ha'pennies to boot) The French *did* have a decimalized calendar (and time, too, I think). ___ 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] Tissot wrist watch
For mechanical watch movements such as Rolex and Patek quality used a microphone to resolve the sounds of the escapement reference. They had a strip chart recorder on the top and displayed the recovered acoustical signature onto a plot of against the internal crystal reference which ran a stepper motor moving the paper. I believe that the manufacturer was Heuer. Last look was 20 yrs ago. Same idea for 32k768 bender time references different type of acoustical pickup then lots of gain and a BP filter at 32k8. No experience with newer 4M194 style watches. Maybe build an RF induction pickup with a 4M2 filter and amplifier to try to find it then more cleanup to get it to a counter Greg On 4/6/2011 5:32 AM, asma...@fc.up.pt wrote: Dear Time-Nuts, I am afraid of being off topic with the following. If so, I sincerely apologize. I would like to know the precision to be expected on time keeping from a Tissot mod. J378/478 S wrist watch and how could be verified the fulfilment of that specification without waiting for a long time (probably more than one month) to observe an error of one second. Instructions on how to build a test basket or similar layout would be most appreciated. Thanks in advance, Antonio CT1TE ___ 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] Proton Precession Magnetometer
I've used and repaired EGG proton maggies in the past. I can't remember a lot from them other than that, as you indicated there wasn't a lot to them. I think its best to figure out what you need, because putting a proton maggie in a box may be physically problematic. If you really think that's the way to go, you might want to pick up this Geometrics/EGG unit on ebay: ebay item #380328909088 Frankly, I've seen people use a cheap TCM2 magnetic compass fairly successfully as a magnetometer, but they were mapping cables, etc. Also, a google of egg magnetometer pdf will pull up a few documents that may be of use. Brent On Tue, Apr 5, 2011 at 10:36 PM, John Miles jmi...@pop.net wrote: Hi, I am boxing up my LPRO rubidium source in a steel box. The device is to be thermostated by controlling a small fan outside the box to keep the LPRO at about 40*C. Although the unit is in a mumetal box I assume there may be some penetration of earths magnetic field. The steel box should help that. To test this I want to build a very stable magnetometer. Now I know that all you need is a jar of water or kerosene to give you protons, and a coil around the jar to kick the protons and then listen to them sing. I have also been told that these instruments do not work in a laboratory, as the AC magnetic field drives them crazy. I am thinking of lock in amplifiers and phase locked loops. Also toroidal coil or paired coils. Can anyone in this group point me to an easy to construct and fiercely accurate design to build? Check out Joe Geller's work ( http://www.gellerlabs.com/index.html ) and also Jim Koehler's ( http://www.geotech1.com/cgi-bin/pages/common/index.pl?page=magfile=/info/ko ehler/index.datzoom ). The May 2007 issue of Circuit Cellar had a shorter article by Jim. -- john, KE5FX ___ 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] Tissot wrist watch
Greg Broburg wrote: For mechanical watch movements such as Rolex and Patek quality used a microphone to resolve the sounds of the escapement reference. ALL watch manufacturers used such a system, even Timex. They had a strip chart recorder on the top and displayed the recovered acoustical signature onto a plot of against the internal crystal reference which ran a stepper motor moving the paper. I believe that the manufacturer was Heuer. Last look was 20 yrs ago. There were a dozen or more manufacturers of watch timing machines. One of the most popular was the Vibrograf. Greinier was another. They were basically a mechanical version of an oscilloscope. Inside the machine was a crystal, or tuning fork, reference, which was divided down to a handful of frequencies that corresponded to the popular balance wheel rates of the various sized watches. The resulting frequency (sinewave) was fed to a power amplifier stage that drove a synchronous motor. The motor directly drove a drum that had a one turn spiral of wire wrapped around it. That wire formed the sweep. Geared to the motor was a paper feed system that fed a strip of paper over the top of the drum. It also drove a standard typewriter ribbon to make a mark on the paper. On the other side of the system, a piezoelectric transducer picked up the mechanical vibrations of the watch, and a high gain adjustable amplifier amplified the vibrations to a high enough level that they could drive the coil on a solenoid device that drove a bail that could strike the drum. When the bail struck the drum, it left a mark on the paper strip at the intersection of the bail, and the spiral wire. The watchmaker knew the gain was adjusted correctly when the bail ticked with a nice regular pattern at the same rate as the watch's balance wheel. Because of the inter relationships of the various parts, the marks on the paper would represent a straight line when the watch's rate matched the timing machine's. They would veer off at a positive, or negative angle if the watch was above, or below the desired rate. The timing machines typically have a plastic wheel with a set of lines on it that can be rotated to match the pitch of the line on the tape. There was a dial that could be referenced to read out the watch's error. The absolute accuracy of the timing machine was not of great importance. The way it typically was used, was to quickly set the watch to what the machine thought was correct, and then the watch was given to the owner with the instructions to wear it normally, and bring it back in a week... but don't reset the time. At the end of the week, the watchmaker would compare the watch's time with the shop's standard clock, calculate the owner's personal error, and then set the dial on the timing machine to compensate for that error. The watchmaker would then put the watch on the machine, and adjust the balance wheel to match the dial on the machine. -Chuck Harris Same idea for 32k768 bender time references different type of acoustical pickup then lots of gain and a BP filter at 32k8. No experience with newer 4M194 style watches. Maybe build an RF induction pickup with a 4M2 filter and amplifier to try to find it then more cleanup to get it to a counter Greg On 4/6/2011 5:32 AM, asma...@fc.up.pt wrote: Dear Time-Nuts, I am afraid of being off topic with the following. If so, I sincerely apologize. I would like to know the precision to be expected on time keeping from a Tissot mod. J378/478 S wrist watch and how could be verified the fulfilment of that specification without waiting for a long time (probably more than one month) to observe an error of one second. Instructions on how to build a test basket or similar layout would be most appreciated. Thanks in advance, Antonio CT1TE ___ 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] Tissot wrist watch
Picking up the crystal frequency should work with older quartz watches that use a trimmer capacitor to adjust the crystal frequency. But recent quartz watches use a crystal that's deliberately too high frequency, and a divider chain that drops one oscillator pulse every so often to bring the overall rate down to close to the correct value. This all-digital method is cheaper and more stable than using a trimcap. The time between dropped pulses is programmed individually for each watch after measuring the actual crystal frequency. To measure the timekeeping of such a watch, you pick up the sound or magnetic pulses from the second hand's motor (not the crystal), and observe how they drift compared with a reference 1 Hz source over a period of 10 minutes or 16 minutes or whatever the cycle time of the pulse-dropping process is for that model of watch. If you're watching on a timegrapher, you will see the timing running fast for a while, then jump back periodically giving a sawtooth-shaped display. Dave On Wed, Apr 6, 2011 at 7:33 AM, Greg Broburg semif...@comcast.net wrote: For mechanical watch movements such as Rolex and Patek quality used a microphone to resolve the sounds of the escapement reference. They had a strip chart recorder on the top and displayed the recovered acoustical signature onto a plot of against the internal crystal reference which ran a stepper motor moving the paper. I believe that the manufacturer was Heuer. Last look was 20 yrs ago. Same idea for 32k768 bender time references different type of acoustical pickup then lots of gain and a BP filter at 32k8. No experience with newer 4M194 style watches. Maybe build an RF induction pickup with a 4M2 filter and amplifier to try to find it then more cleanup to get it to a counter Greg On 4/6/2011 5:32 AM, asma...@fc.up.pt wrote: Dear Time-Nuts, I am afraid of being off topic with the following. If so, I sincerely apologize. I would like to know the precision to be expected on time keeping from a Tissot mod. J378/478 S wrist watch and how could be verified the fulfilment of that specification without waiting for a long time (probably more than one month) to observe an error of one second. Instructions on how to build a test basket or similar layout would be most appreciated. Thanks in advance, Antonio CT1TE ___ 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] Portable standard
As usual, lots of good replies and more links to things for me to read :-) On the topic of rubidiums, I see three different brands on ebay. The FE units sell for much more. What are the differences between the three brands? Is the FE brand worth the price? Considering that these are all used units, how long before the rubidium lamp is dead? What about powering these things? Any precautions? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Oncore battery backup
Recently, the local area had an extended power outage. I have the Z3801A on a UPS, but the outage lasted over an hour and the UPS didn't. I have the information about adding a battery to the Oncore to allow for faster startup. Is it safe to use a supercap instead of a battery? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oncore battery backup
On 4/6/11 9:00 AM, Joseph Gray wrote: Recently, the local area had an extended power outage. I have the Z3801A on a UPS, but the outage lasted over an hour and the UPS didn't. I have the information about adding a battery to the Oncore to allow for faster startup. Is it safe to use a supercap instead of a battery? Isn't your real problem going to be that the oven on the oscillator has cooled off? Or does the GPS lose the whole almanac, so the time to first fix is forever? ___ 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] Oncore battery backup
Isn't your real problem going to be that the oven on the oscillator has cooled off? Or does the GPS lose the whole almanac, so the time to first fix is forever? Yes, the Oncore looses the almanac. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Portable standard
From what I have learned from people much smarter than me, the one to buy is the PRS10 from Stanford Research. They were going for under 200 a few years ago but are now up at 500 or more. From what I understand this item is worth that money. I own Efratom FRS-Ns which I paid 1000 each for 15 years ago. The bulbs do not burn out, there is no filament in them. The bulbs are a glass container which live inside of an RF excitation coil. If the unit stops working it is generally not a failed bulb On mine there was a resistor (10k) which changed to 5k and stopped it. This resistor is a known problem, same resistor failure in many if not all units after a few thousand hours of operation. I have been party to repairing 10 FRK rubes. In these units the tantalum bypass capacitors are all suspect, some of them go shorted. We replaced all of these caps and retuned them and they are all up and running now. I have been bidding for an EPS Here is a quote from a few years ago from Corby Dawson. Rubidium standard life Thu, 12 Nov 2009 10:13:22 -0800 Post Comments Glenn, The lamp is usually the limiting factor. The PRS10 advertises its lamp life to be 20 years. HP bulbs last a bit longer. Tracor bulbs fail with a different mechanism and last maybe 10 years. Efratom bulbs last at least 10 to 15 years. The rejuvenation you referred to is for lamps that have been off for years in uncontrolled temperature environments. These bulbs are not bad, the rubidium has just migrated to the wrong part of the bulb. With a little effort it can be coaxed back where it belongs. A really bad bulb can not be rejuvenated as the rubidium has been absorbed into the inner lining of the bulb envelop. Sometimes these bad bulbs show a definite envelope darkening to the eye. Hope this helps. Corby Dawson On 4/6/2011 9:46 AM, Joseph Gray wrote: As usual, lots of good replies and more links to things for me to read :-) On the topic of rubidiums, I see three different brands on ebay. The FE units sell for much more. What are the differences between the three brands? Is the FE brand worth the price? Considering that these are all used units, how long before the rubidium lamp is dead? What about powering these things? Any precautions? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oncore battery backup
This will be interesting. I have not added a battery to my 3801. Have the same issue annoying but in general not enough to get me to do something. But believe it may be as simple as taking a cr3026 lithium as an example and holder. Slap it on the back and change the battery every so often. Doing something with recharge-ables and super caps adds a lot of complexity. Using the disposable battery should make this a ground and battery connection. Do not believe a diode is required. But this approach only works if the almanac memory and such draws very very low current. Might guess in the 1-10 ua. If its a pig you could always use 2 AA alkalines. Regards Paul WB8TSL On Wed, Apr 6, 2011 at 12:19 PM, Joseph Gray jg...@zianet.com wrote: Isn't your real problem going to be that the oven on the oscillator has cooled off? Or does the GPS lose the whole almanac, so the time to first fix is forever? Yes, the Oncore looses the almanac. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Portable standard
Hi Joe: Do NOT put the batteries near the OCXO! Although you may get the advantage of thermal mass the problem with having acid fumes near copper traces on printed circuit boards will lead to trace etching. Can you guess how I know this. http://www.prc68.com/I/timefreq.shtml#Gibbs Pulse (Burp) charging is not snake oil, although I thought it was until I saw it in action. http://www.prc68.com/I/timefreq.shtml#Gibbs http://www.prc68.com/I/PropelBB590.shtml This was in relation to Ni-Cad and Ni-MH chemistry, so not sure how it works on lead acid. Have Fun, Brooke Clarke http://www.PRC68.com Joseph Gray wrote: If I were to buy an HP 10811A OCXO to use as a portable, battery powered frequency standard, how would you recommend that it be powered and packaged? Assume that the final package would be powered 24/7 and sitting on a shelf most of the time. Prior to portable use, it would be checked against my GPSDO. Portable use would probably be at worse a few days, but more likely less than a day. I'm thinking of using a couple of 12V, 7AH SLA batteries and float charging them. Some charge circuits use pulsing current for SLA batteries. Would this affect the OCXO? Obviously too much air flow will be a problem. Can the OCXO, batteries and associated circuitry be sealed in a box with no vent holes (not strictly air tight)? What about putting the OCXO in a small styrofoam box by itself? Will that cause overheating or other issues? How about vent holes in the overall enclosure and baffles around the OCXO to minimize air flow? Should I forget the whole idea and just buy a rubidium? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oncore battery backup
On Wed, Apr 6, 2011 at 9:00 AM, Joseph Gray jg...@zianet.com wrote: Recently, the local area had an extended power outage. I have the Z3801A on a UPS, but the outage lasted over an hour and the UPS didn't. I have the information about adding a battery to the Oncore to allow for faster startup. Is it safe to use a supercap instead of a battery? I have an Oncore too. I added a coin size battery salvaged from an old PC. It is easy enough to do there is a header pin just for that purpose. The Motorola user manual says the battery woks better because it lasts longer but that was written ten years ago. If you use a cap you will want to add a resistor in series to limit current. The Onore looses the almanac and all settings if there is no battery. There is zero non-volatile memory in the device. -- = Chris Albertson Redondo Beach, California ___ 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] Tissot wrist watch
On 4/6/2011 10:33 AM, Greg Broburg wrote: For mechanical watch movements such as Rolex and Patek quality used a microphone to resolve the sounds of the escapement reference. They had a strip chart recorder on the top and displayed the recovered acoustical signature onto a plot of against the internal crystal reference which ran a stepper motor moving the paper. I believe that the manufacturer was Heuer. Last look was 20 yrs ago. Same idea for 32k768 bender time references different type of acoustical pickup then lots of gain and a BP filter at 32k8. No experience with newer 4M194 style watches. Maybe build an RF induction pickup with a 4M2 filter and amplifier to try to find it then more cleanup to get it to a counter Greg On 4/6/2011 5:32 AM, asma...@fc.up.pt wrote: Dear Time-Nuts, I am afraid of being off topic with the following. If so, I sincerely apologize. An excellent reference timer is the MicroSet made by Bryan Mumford. It will do exactly what you want and even has an available GPS reference if you need the accuracy. I've used one for quite a few years and have no connection with Mumford except as a customer. Bill S I would like to know the precision to be expected on time keeping from a Tissot mod. J378/478 S wrist watch and how could be verified the fulfilment of that specification without waiting for a long time (probably more than one month) to observe an error of one second. Instructions on how to build a test basket or similar layout would be most appreciated. Thanks in advance, Antonio CT1TE ___ 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] Transmission line question
Hello, If I have a pin with two 50 ohm lines leading in opposite directions from its land (let's say they are arbitrarily long so as to truly look like 50 ohm lines), what is the effective impedance that the pin sees? Thanks, Donald ___ 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] Transmission line question
25 Ohms. John WA4WDL -- From: Don Otknow donald.otk...@gmail.com Sent: Wednesday, April 06, 2011 2:00 PM To: time-nuts@febo.com Subject: [time-nuts] Transmission line question Hello, If I have a pin with two 50 ohm lines leading in opposite directions from its land (let's say they are arbitrarily long so as to truly look like 50 ohm lines), what is the effective impedance that the pin sees? Thanks, Donald ___ 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] Oncore battery backup
Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Just be careful though - in some UPS units the battery is live to the mains! The APC ones seem to be OK. Murray ___ 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] Portable standard - Rb query
Joe, I have several of the FEI units. You pay more for these, because (assuming you get the right one) they have a DDS synthesizer included, which (with suitable modification) allows them to operate from about 1kHz to 15MHz in 10mHz steps. Some models require +15V and +5V, others just +15V. My preferred unit is the FE-5680A. I have mine mounted on a large aluminium plate and powered by a switch-mode computer supply. I have set the default frequency to 10MHz. The LPRO type are fine if you want a simple fixed 10MHz reference, and are in general cheaper and use less power. As for lifetime, they seem to go forever. That said, there's no need to power them continuously since (in my experience) they are close to their final frequency 5 minutes from a cold start. Power consumption is higher than an OCXO, but they really do make a great portable standard. That's what I'd use (in fact, that's what I do use). Murray ___ 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] Tissot wrist watch
Although we normally deal with nanoseconds and picoseconds here on this list, the essence of being a time nut and the allure of precision timekeeping is there in the micro- and milli-second world as well. I can personally tell you that the Allan deviation of a pendulum clock is equal or more interesting than an H-maser. As Bill just mentioned, for those of you interested in wristwatch or pendulum clock timing, please see Bryan's site: http://www.bmumford.com/microset.html Antonio, I used one of Bryan's Microset timers to measure my (WWVB radio controlled) wristwatch: http://www.leapsecond.com/pages/Junghans/ There's no need to wait a month before you see a 1 second error! -- If you can measure to 1/10 second you only have to wait a few days, right? If you can measure to 1/1000 second you can see the error within an hour. If you use a Microset measure to 1/100 second you can time and rate errors within seconds or minutes! But at this level you will also be able to measure variations due to temperature or humidity or pressure or orientation, or phase of the moon, etc. You can monitor time, rate over time; rate drift over time; rate over shock, etc. The Microset is really nice. Note that just because your watch is accurate to 1 second a month does not mean it will be accurate to 12 second a year or 2 minutes a decade or 1/4 second a week or 1.4 ms an hour. The extreme non-linearity in performance is part of the great fun of analyzing the performance of any clock, in the short- and long-term, from mechanical to quartz to atomic clocks. /tvb Dear Time-Nuts, I am afraid of being off topic with the following. If so, I sincerely apologize. I would like to know the precision to be expected on time keeping from a Tissot mod. J378/478 S wrist watch and how could be verified the fulfilment of that specification without waiting for a long time (probably more than one month) to observe an error of one second. Instructions on how to build a test basket or similar layout would be most appreciated. Thanks in advance, Antonio CT1TE ___ 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] Transmission line question
Its would be 25 ohms if both lines are 50 ohms and 0 reactence. On Wed, Apr 6, 2011 at 2:07 PM, jmfranke jmfra...@cox.net wrote: 25 Ohms. John WA4WDL -- From: Don Otknow donald.otk...@gmail.com Sent: Wednesday, April 06, 2011 2:00 PM To: time-nuts@febo.com Subject: [time-nuts] Transmission line question Hello, If I have a pin with two 50 ohm lines leading in opposite directions from its land (let's say they are arbitrarily long so as to truly look like 50 ohm lines), what is the effective impedance that the pin sees? Thanks, Donald ___ 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] Tissot wrist watch
Many moons ago I remember having discussions about the performance of 32k768 benders. We used them in pacemakers, mother natures 37.0 deg crystal ovens. For the watch chip designers the temp curves were a part of their lives. The daily usage was a part of the plan for where to set the rock. The wrist temperature is a part of it and the number of hours each day on the wrist. For watches that sat unworn the times drifted a bunch. I believe that that was the origin of the 4M194304 references which started showing up on the fancy translate spensive, watches. Imagine drift numbers for a watch sitting on a dresser in an unheated cabin over winter months and one closer to the Equator. Not an easy way to compensate the drift without a temp tracker and a varactor in the watch. I guess that that is now old news. Greg On 4/6/2011 12:44 PM, Tom Van Baak wrote: Although we normally deal with nanoseconds and picoseconds here on this list, the essence of being a time nut and the allure of precision timekeeping is there in the micro- and milli-second world as well. I can personally tell you that the Allan deviation of a pendulum clock is equal or more interesting than an H-maser. As Bill just mentioned, for those of you interested in wristwatch or pendulum clock timing, please see Bryan's site: http://www.bmumford.com/microset.html Antonio, I used one of Bryan's Microset timers to measure my (WWVB radio controlled) wristwatch: http://www.leapsecond.com/pages/Junghans/ There's no need to wait a month before you see a 1 second error! -- If you can measure to 1/10 second you only have to wait a few days, right? If you can measure to 1/1000 second you can see the error within an hour. If you use a Microset measure to 1/100 second you can time and rate errors within seconds or minutes! But at this level you will also be able to measure variations due to temperature or humidity or pressure or orientation, or phase of the moon, etc. You can monitor time, rate over time; rate drift over time; rate over shock, etc. The Microset is really nice. Note that just because your watch is accurate to 1 second a month does not mean it will be accurate to 12 second a year or 2 minutes a decade or 1/4 second a week or 1.4 ms an hour. The extreme non-linearity in performance is part of the great fun of analyzing the performance of any clock, in the short- and long-term, from mechanical to quartz to atomic clocks. /tvb Dear Time-Nuts, I am afraid of being off topic with the following. If so, I sincerely apologize. I would like to know the precision to be expected on time keeping from a Tissot mod. J378/478 S wrist watch and how could be verified the fulfilment of that specification without waiting for a long time (probably more than one month) to observe an error of one second. Instructions on how to build a test basket or similar layout would be most appreciated. Thanks in advance, Antonio CT1TE ___ 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] Oncore battery backup
My 2 cents is that a UPS is very inefficient on power conversion. If all you want to do is preserver the almanac. Lets say a 10 ua need. If on the other hand you want to keep everything running then larger batteries make sense. Accept for one gotcha. The chargers on the small UPS's 70-100 watt class are not really set up to do a good job on a much larger battery set. With humor they aren't very good for small batteries either. Regards Paul. On Wed, Apr 6, 2011 at 2:25 PM, Murray Greenman murray.green...@rakon.comwrote: Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Just be careful though - in some UPS units the battery is live to the mains! The APC ones seem to be OK. Murray ___ 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] Oncore battery backup
At 12:15 PM 4/6/2011, Jim Lux wrote... Isn't your real problem going to be that the oven on the oscillator has cooled off? Or does the GPS lose the whole almanac, so the time to first fix is forever? The more significant problem is that it loses its surveyed position, so it takes even more than forever to recover. ___ 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] Transmission line question
sounds like an application for a simple power splitter on the board. Greg On 4/6/2011 12:52 PM, paul swed wrote: Its would be 25 ohms if both lines are 50 ohms and 0 reactence. On Wed, Apr 6, 2011 at 2:07 PM, jmfrankejmfra...@cox.net wrote: 25 Ohms. John WA4WDL -- From: Don Otknowdonald.otk...@gmail.com Sent: Wednesday, April 06, 2011 2:00 PM To:time-nuts@febo.com Subject: [time-nuts] Transmission line question Hello, If I have a pin with two 50 ohm lines leading in opposite directions from its land (let's say they are arbitrarily long so as to truly look like 50 ohm lines), what is the effective impedance that the pin sees? Thanks, Donald ___ 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] SI Unit Problems
On 04/06/2011 03:19 PM, Jim Lux wrote: On 4/5/11 7:38 PM, Greg Broburg wrote: The number 6 and derivations thereof were presented to the world of science from the numerologists. Time was arranged as parts of a day, 24 hours 60 minutes per hour 60 seconds per minute. Very tenuous at best. I propose that we consider 100 seconds in a minute, 100 minutes in an hour, and 10 hours in a day. People could handle that with an IPhone ap, right? Then there's the Babylonians, who used a number system where 60 was important. 60 has lots of factors, which makes dividing things up into equal sized chunks easy. (as my daughter said when much younger, and doing fractions in math, curse those Babylonians). The fact that a year is about 360 days long (6*60) also feeds into it. You really needed the invention and adoption of place value for a decimalized system to work well, and that didn't come along til around 700-800 C.E., I think. By then, the fractional measurement approach and customary units were well entrenched. Sure, although King John standardized the yard and inch and pound and such in the 1200s, I'm sure that the units themselves were already in use for a long time. Currency is also done in a fractional system (pieces o'eight, 12pence/shilling with ha'pennies to boot) The French *did* have a decimalized calendar (and time, too, I think). You can't do much about the the number of days per year, and a 400 day calender would be useless since it would be hard to pin things which depends on seasons to a fixed date, month or so... Another annoying detail is that the SI second takes about 86400 seconds for a twist around the axis such that the closest star is at the same place in the sky again. If you want to get the closes decimal number it would be 10 new seconds and such a second would require 86400 * 9192631770 / 10 = 864 * 919263177 / 100 = 7942433849.28 cycles per new second of a caesium reference. Not a particular neat number, but in reality it would not be too strange when considering how a caesium clock actually works. Going full decimal is not practical. I does not support it. Cheers, Magnus ___ 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] Tissot wrist watch
On Wed, Apr 6, 2011 at 3:54 PM, Greg Broburg semif...@comcast.net wrote: and one closer to the Equator. Not an easy way to compensate the drift without a temp tracker and a varactor in the watch. I guess that that is now old news. With affordable and tiny MEMS sensors such as temperature, humidity, linear acceleration, and magnetism available, I expect cheap 32.768 kHz TCXO or high quality watches to integrate such sensors for high-end crystal disciplined watches. ___ 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] Portable standard - Rb query
Murray, Do you have any details on the DDS? How difficult is it to change on the fly if I wanted to? Is the FE-5680A that you like +15V only? Joe Gray W5JG On Wed, Apr 6, 2011 at 12:34 PM, Murray Greenman murray.green...@rakon.com wrote: Joe, I have several of the FEI units. You pay more for these, because (assuming you get the right one) they have a DDS synthesizer included, which (with suitable modification) allows them to operate from about 1kHz to 15MHz in 10mHz steps. Some models require +15V and +5V, others just +15V. My preferred unit is the FE-5680A. I have mine mounted on a large aluminium plate and powered by a switch-mode computer supply. I have set the default frequency to 10MHz. The LPRO type are fine if you want a simple fixed 10MHz reference, and are in general cheaper and use less power. As for lifetime, they seem to go forever. That said, there's no need to power them continuously since (in my experience) they are close to their final frequency 5 minutes from a cold start. Power consumption is higher than an OCXO, but they really do make a great portable standard. That's what I'd use (in fact, that's what I do use). Murray ___ 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] Portable standard - Rb query
Quick? How much do you want to pay? $1500 perhaps. On Wed, Apr 6, 2011 at 3:47 PM, Joseph Gray jg...@zianet.com wrote: Murray, Do you have any details on the DDS? How difficult is it to change on the fly if I wanted to? Is the FE-5680A that you like +15V only? Joe Gray W5JG On Wed, Apr 6, 2011 at 12:34 PM, Murray Greenman murray.green...@rakon.com wrote: Joe, I have several of the FEI units. You pay more for these, because (assuming you get the right one) they have a DDS synthesizer included, which (with suitable modification) allows them to operate from about 1kHz to 15MHz in 10mHz steps. Some models require +15V and +5V, others just +15V. My preferred unit is the FE-5680A. I have mine mounted on a large aluminium plate and powered by a switch-mode computer supply. I have set the default frequency to 10MHz. The LPRO type are fine if you want a simple fixed 10MHz reference, and are in general cheaper and use less power. As for lifetime, they seem to go forever. That said, there's no need to power them continuously since (in my experience) they are close to their final frequency 5 minutes from a cold start. Power consumption is higher than an OCXO, but they really do make a great portable standard. That's what I'd use (in fact, that's what I do use). Murray ___ 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] Oncore battery backup
On Wed, Apr 6, 2011 at 11:25 AM, Murray Greenman murray.green...@rakon.com wrote: Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Because with an Oncore you can't even move it or swap a cable. Anything that causes the power to go down even for an instant clears the memory and a simple $1 battery will fix this problem and last for many years. Yes get the UPS but the Oncore can be greatly improved by such a simple and cheap fix that it makes sense to do it. That said, there are commands you can send to the Oncore that will load an almanac and a survey location. So even after a memory loss you can be up running in a few seconds after this data are loaded from a computer. -- = Chris Albertson Redondo Beach, California ___ 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] Oncore battery backup
Oh there you go. You have made me think. Indeed there are commands that would easily be sent from a small basic language program on a Basic stamp or SXB or Pic etc etc. I think its only 2-3 commands also. But I just need to get off my *() and add the battery before getting silly. Regards Paul On Wed, Apr 6, 2011 at 3:50 PM, Chris Albertson albertson.ch...@gmail.comwrote: On Wed, Apr 6, 2011 at 11:25 AM, Murray Greenman murray.green...@rakon.com wrote: Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Because with an Oncore you can't even move it or swap a cable. Anything that causes the power to go down even for an instant clears the memory and a simple $1 battery will fix this problem and last for many years. Yes get the UPS but the Oncore can be greatly improved by such a simple and cheap fix that it makes sense to do it. That said, there are commands you can send to the Oncore that will load an almanac and a survey location. So even after a memory loss you can be up running in a few seconds after this data are loaded from a computer. -- = Chris Albertson Redondo Beach, California ___ 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] Oncore battery backup (answer to question)
Hi Joe, Yes you can use a supercap. It will directly replace the ni-cad Just make sure the voltage rating is high enough, e.g. 5V Ebay item 160495558462 looks good. Robert G8RPI. --- On Wed, 6/4/11, Joseph Gray jg...@zianet.com wrote: From: Joseph Gray jg...@zianet.com Subject: [time-nuts] Oncore battery backup To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: Wednesday, 6 April, 2011, 17:00 Recently, the local area had an extended power outage. I have the Z3801A on a UPS, but the outage lasted over an hour and the UPS didn't. I have the information about adding a battery to the Oncore to allow for faster startup. Is it safe to use a supercap instead of a battery? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oncore battery backup
paulsw...@gmail.com said: The chargers on the small UPS's 70-100 watt class are not really set up to do a good job on a much larger battery set. What's the problem and/or what do the larger units do differently? -- Several/many years ago, I got a UPS when somebody on this list (I think) pointed out that the APC units would tell you the line voltage. Mostly, I wanted something to run a PC that monitors line voltage if/when it went out so that worked out nicely. I looked at the charts and did some quick calculations. The smaller units don't have many watt-hours. I ended up getting a big unit in order to get hours rather than minutes of holdover. -- These are my opinions, not necessarily my employer's. 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] Oncore battery backup
On 4/6/11 11:25 AM, Murray Greenman wrote: Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Just be careful though - in some UPS units the battery is live to the mains! The APC ones seem to be OK. The other thing is that some UPS's have a thermal limit on how long they can run (e.g. 20 minutes before they melt)... suitable fans might help (as opposed to having it in a dust filled box under your desk) ___ 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] Portable standard
So far I'm quite happy with the Temex LPFRS-01 I purchased from ebay. The unit I purchased uses a single 24 volt supply and came with a heat sink and a circut board with a trim pot to fine tune the frequency. The connector on the board is a standard IDC style and the connectors on actual unit are also standard. The unit I purchased also appears to meet the published short term stability spec of 3 x 10-12 / 100 seconds for the standard unit. - Original Message From: Joseph Gray jg...@zianet.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wed, April 6, 2011 8:46:15 AM Subject: Re: [time-nuts] Portable standard As usual, lots of good replies and more links to things for me to read :-) On the topic of rubidiums, I see three different brands on ebay. The FE units sell for much more. What are the differences between the three brands? Is the FE brand worth the price? Considering that these are all used units, how long before the rubidium lamp is dead? What about powering these things? Any precautions? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oncore battery backup
Well some good comments about the UPS ability to handle the heat from running for a long time. Absolutely true. The charger does not deliver enough current to effectively charge the battery set if its larger then the original design. As such the battery life is effected up to 50% and certainly the operating capacity. They build these things cheap as they can to preserver sales margins and a average life of 2 to 3 years. Regulation of the charge voltages/currents to optimize SLA life is sloppy. Don't get me at all wrong. A cheap ups and 2 X batteries should do something and at the costs they want these days, its pretty amazing actually. Heck have you seen the cost for a good set of sla batteries these days? I do not mean homedepot been on the shelf dead for 3 years either. There is one other reasonable approach. Been around for years and pretty sure its on the web for the 3801. Essentially float a battery set across the 24 volt input with a good grade charger. This is pretty much how HP does there RB and CS standards. You do not have the inefficient up conversion costs of a UPS. Thats exactly how I run my FRS in the basement and on 2 X 14 amp SLA batteries and get around 12 hours as I recall. And thats not killing the batteries. Bad idea at what they cost these days. By the way I drop the distribution divider chains and such when I go to battery Even the leds. Regards Paul. On Wed, Apr 6, 2011 at 4:21 PM, Jim Lux jim...@earthlink.net wrote: On 4/6/11 11:25 AM, Murray Greenman wrote: Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Just be careful though - in some UPS units the battery is live to the mains! The APC ones seem to be OK. The other thing is that some UPS's have a thermal limit on how long they can run (e.g. 20 minutes before they melt)... suitable fans might help (as opposed to having it in a dust filled box under your desk) ___ 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] Oncore battery backup
I remember reading in one of the docs I have for the Oncore that Motorolla recommended a battery over a cap mainly for practical reasons. But now all I can find is some basic specs for what you need to conect to pin-1 on the header BATTERY (Externally applied backup power) Voltage: 2.5 V to 5.25 V Current: 5 μA typical @ 2.5 V 100 μA typical @ 5.0 V On Wed, Apr 6, 2011 at 12:54 PM, Joseph Gray jg...@zianet.com wrote: Yes, a UPS isn't the most efficient method of running the GPSDO. It was an expedient until the day I run it on batteries. As for backing up the Oncore, power outages are not the only reason. I may need to power down the GPSDO to add mods or other reasons may arise. Having the almanac stored will help. I would still like to know if using a supercap is ok. They are made for memory backup, so why couldn't I use one for the Oncore? I have a few different values on hand. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- = Chris Albertson Redondo Beach, California ___ 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] Oncore battery backup
I would vote for a lithium AA. Something like a Tadiran TL5104 3V6 @ 2A10 hrs Greg On 4/6/2011 2:43 PM, Chris Albertson wrote: I remember reading in one of the docs I have for the Oncore that Motorolla recommended a battery over a cap mainly for practical reasons. But now all I can find is some basic specs for what you need to conect to pin-1 on the header BATTERY (Externally applied backup power) Voltage: 2.5 V to 5.25 V Current: 5 μA typical @ 2.5 V 100 μA typical @ 5.0 V On Wed, Apr 6, 2011 at 12:54 PM, Joseph Grayjg...@zianet.com wrote: Yes, a UPS isn't the most efficient method of running the GPSDO. It was an expedient until the day I run it on batteries. As for backing up the Oncore, power outages are not the only reason. I may need to power down the GPSDO to add mods or other reasons may arise. Having the almanac stored will help. I would still like to know if using a supercap is ok. They are made for memory backup, so why couldn't I use one for the Oncore? I have a few different values on hand. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Transmission line question
Am I missing something?? Surely it depends on whether the lines are terminated otherwise by the time time a pulse has travelled to the end and back they will be a complex impedance and will be frequency dependent 2 open stubs ?? If terminated then 25 ohms, but why does it matter what a high impedance device like a PIN sees ?? Alan G3NYK - Original Message - From: Greg Broburg semif...@comcast.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, April 06, 2011 8:59 PM Subject: Re: [time-nuts] Transmission line question sounds like an application for a simple power splitter on the board. Greg On 4/6/2011 12:52 PM, paul swed wrote: Its would be 25 ohms if both lines are 50 ohms and 0 reactence. On Wed, Apr 6, 2011 at 2:07 PM, jmfrankejmfra...@cox.net wrote: 25 Ohms. John WA4WDL -- From: Don Otknowdonald.otk...@gmail.com Sent: Wednesday, April 06, 2011 2:00 PM To:time-nuts@febo.com Subject: [time-nuts] Transmission line question Hello, If I have a pin with two 50 ohm lines leading in opposite directions from its land (let's say they are arbitrarily long so as to truly look like 50 ohm lines), what is the effective impedance that the pin sees? Thanks, Donald ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oncore battery backup
Really have to open the 3801 up and go find the magical header. 2011/4/6 Greg Broburg semif...@comcast.net I would vote for a lithium AA. Something like a Tadiran TL5104 3V6 @ 2A10 hrs Greg On 4/6/2011 2:43 PM, Chris Albertson wrote: I remember reading in one of the docs I have for the Oncore that Motorolla recommended a battery over a cap mainly for practical reasons. But now all I can find is some basic specs for what you need to conect to pin-1 on the header BATTERY (Externally applied backup power) Voltage: 2.5 V to 5.25 V Current: 5 μA typical @ 2.5 V 100 μA typical @ 5.0 V On Wed, Apr 6, 2011 at 12:54 PM, Joseph Grayjg...@zianet.com wrote: Yes, a UPS isn't the most efficient method of running the GPSDO. It was an expedient until the day I run it on batteries. As for backing up the Oncore, power outages are not the only reason. I may need to power down the GPSDO to add mods or other reasons may arise. Having the almanac stored will help. I would still like to know if using a supercap is ok. They are made for memory backup, so why couldn't I use one for the Oncore? I have a few different values on hand. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Oncore battery backup (answer to question)
Robert, I completely disagree with such a simple answer ! Lets review the issue here. Joe has not given any information as to the equipment in question, nor has he stated his desired goals other then by assumptions based upon his questions. First, which Oncore receiver is he using ? If it is the older series such as a GT+ or UT+ they are designed to have a Lithium 3 volt cell soldered onto the board. The memory draws 5 micro amps at 3 volts and 100 micro amps at 5 volts. There is an external connection available to provide the battery back-up off board with a caution of NOT exceeding 5 volts. The non rechargeable Lithium COIN battery has a discharge function that holds its voltage fairly constant right up until the end. They will last a very long time with just 5 micro amps of discharge. The problem with the Super Cap is the charge circuitry could damage the GPS if not properly protected. The Super Cap will not last as long as the Lithium; we are talking years here under the right condition. Unless you are skilled at changing small foot print surface mount components, presuming the memory chip is still available, you stand the chance of destroying the receiver. Why subject yourself to additional unnecessary expense. Why add all that complexity to an otherwise simple application. If you add up the cost of the CAP and all the parts to charge it and protect the load, I think that would exceed the cost of the battery. If your whole existence relies on a single back-up strategy to save your butt, then you should not be there in the first place. So, I think it is time for Joe to think all of this through with some proper goals stated and reasoned thought applied. BillWB6BNQ Robert Atkinson wrote: Hi Joe, Yes you can use a supercap. It will directly replace the ni-cad Just make sure the voltage rating is high enough, e.g. 5V Ebay item 160495558462 looks good. Robert G8RPI. --- On Wed, 6/4/11, Joseph Gray jg...@zianet.com wrote: From: Joseph Gray jg...@zianet.com Subject: [time-nuts] Oncore battery backup To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: Wednesday, 6 April, 2011, 17:00 Recently, the local area had an extended power outage. I have the Z3801A on a UPS, but the outage lasted over an hour and the UPS didn't. I have the information about adding a battery to the Oncore to allow for faster startup. Is it safe to use a supercap instead of a battery? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Oncore battery backup
paulsw...@gmail.com said: The charger does not deliver enough current to effectively charge the battery set if its larger then the original design. As such the battery life is effected up to 50% and certainly the operating capacity. I'm missing something. I'd expect it to just charge slower. What's wrong with that? (as long as you are willing to wait longer and the unit doesn't overheat and ...) Actually, I'd expect charging slower to be (slightly) better for battery life. Consider systems that charge batteries from solar cells. They work fine on less than full bright sun. -- These are my opinions, not necessarily my employer's. 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] Oncore battery backup
From XTOncore Engineering Note Keep Alive BATT Power . 4.75 - 16 Vdc; 0.3 mA (max) or . 3V onboard battery; 15 uA typ., 60 uA max. From UT Plus Backup Power Externally applied backup power Voltage 2.5V to 5.25V Current 5 μA typical @ 2.5 V 100 μA typical @ 5.0 V Optional Lithium Battery Onboard rechargeable cell is charged when main power is on Voltage 3 V Capacity 15 mAh approximately 3 months between charges Recharge approximately 8 hours for a full charge From GT . External 2.5 Vdc to 5.25 Vdc; 5 mA (typ.) @ 2.5 Vdc On 4/6/2011 2:51 PM, paul swed wrote: Really have to open the 3801 up and go find the magical header. 2011/4/6 Greg Broburg semif...@comcast.net mailto:semif...@comcast.net I would vote for a lithium AA. Something like a Tadiran TL5104 3V6 @ 2A10 hrs Greg On 4/6/2011 2:43 PM, Chris Albertson wrote: I remember reading in one of the docs I have for the Oncore that Motorolla recommended a battery over a cap mainly for practical reasons. But now all I can find is some basic specs for what you need to conect to pin-1 on the header BATTERY (Externally applied backup power) Voltage: 2.5 V to 5.25 V Current: 5 μA typical @ 2.5 V 100 μA typical @ 5.0 V On Wed, Apr 6, 2011 at 12:54 PM, Joseph Grayjg...@zianet.com mailto:jg...@zianet.com wrote: Yes, a UPS isn't the most efficient method of running the GPSDO. It was an expedient until the day I run it on batteries. As for backing up the Oncore, power outages are not the only reason. I may need to power down the GPSDO to add mods or other reasons may arise. Having the almanac stored will help. I would still like to know if using a supercap is ok. They are made for memory backup, so why couldn't I use one for the Oncore? I have a few different values on hand. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com mailto: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 mailto: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 5V OCXO in 14DIP has about 1E-9 drift per day
Hello, folks. I'm the seller of the 26MHz OCXOs. Please reply off list if you are interested in some. Thanks. -Pete On 04/06/2011 08:58 AM, Oz-in-DFW wrote: Who is the seller? On 3/28/2011 1:40 PM, beale wrote: Just FYI, I'm not sure how this compares to other similar parts, but I'm seeing about +/- 1 ppb (1E-9) frequency drift per 24 hour period from one sample of the Pletronics OHM40480526, which I've had running for about 10 days now. It runs on +5V and after a warmup current of 250 mA for a few seconds, it draws about 60 mA steady state at room temperature. I'm driving the tuning voltage on pin 1 from a separate +5V reference to avoid variations due to heater current shifts. I use a simple resistive trimpot divider to set the voltage, this is not a GPSDO (yet :-). I'm sure most on this list have more refined tastes in oscillators than this one (and probably want 10 MHz instead of 26 MHz), but I thought it noteworthy because it is so cheap. These parts are currently available online for $2 each. I'm not affiliated with the seller. a few more details: http://www.bealecorner.org/best/measure/time/Pletronics-26MHz-OCXO-tuning.pdf http://www.bealecorner.org/best/measure/time/26MHz-osc-notes.txt ___ 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 5V OCXO in 14DIP has about 1E-9 drift per day
Hi Peter- I just bought 3 of them for 222MHz ham transverter use like Joe has done. Can't wait to get them. Thanks for listing them! -Brian, WA1ZMS On Apr 6, 2011, at 5:56 PM, Peter Loron pet...@standingwave.org wrote: Hello, folks. I'm the seller of the 26MHz OCXOs. Please reply off list if you are interested in some. Thanks. -Pete On 04/06/2011 08:58 AM, Oz-in-DFW wrote: Who is the seller? On 3/28/2011 1:40 PM, beale wrote: Just FYI, I'm not sure how this compares to other similar parts, but I'm seeing about +/- 1 ppb (1E-9) frequency drift per 24 hour period from one sample of the Pletronics OHM40480526, which I've had running for about 10 days now. It runs on +5V and after a warmup current of 250 mA for a few seconds, it draws about 60 mA steady state at room temperature. I'm driving the tuning voltage on pin 1 from a separate +5V reference to avoid variations due to heater current shifts. I use a simple resistive trimpot divider to set the voltage, this is not a GPSDO (yet :-). I'm sure most on this list have more refined tastes in oscillators than this one (and probably want 10 MHz instead of 26 MHz), but I thought it noteworthy because it is so cheap. These parts are currently available online for $2 each. I'm not affiliated with the seller. a few more details: http://www.bealecorner.org/best/measure/time/Pletronics-26MHz-OCXO-tuning.pdf http://www.bealecorner.org/best/measure/time/26MHz-osc-notes.txt ___ 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] Transmission line question
Just for the record I meant pin as in the metal contact of a device, not a PIN diode. So I need the impedance the pin see's (that of the transmission line(s)) to be the same as the output impedance of the pin. Here's an extrapolation on the original question. If this is a high speed digital signal, with frequency elements ranging from say 133 MHz to 1GHz, then what I am really worried about, given the trace lengths (maybe 2 cm each way) is the high frequency components getting reflected or not sent down the line properly. If my source impedance from the the device is 50 ohms, the lines are each 100 ohms, and the terminations at each end are 100 ohms (probably AC terminated, but let's just say 100 ohms for simplicity), am I setting myself up for the best possible signal integrity? Here's a primitive diagram of the setup 100 ohm line 100 ohm line 100 ohm term. to gnd _100 ohm termination to gnd | | | 50 ohm source | Donald ___ 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] Transmission line question
Oh dear it looks like the diagram got horribly screwed up. Well I hope you get what I'm trying to communicate anyways. ___ 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] Transmission line question
Hi Don excuse me I was thinking RF :-)) That should be OK Though it depends what you are trying to do bus termination is usually slightly different to RF. At least you should not get nasty reflections from the ends like that. There may come a problem if you send a pulse from a 100 termination into the network. There will be a little diggle and reflection as it sees the 50 ohm pin as a small mis-match. But if driving out only from the middle I see no problem. (but then I might just be wrong :-)) ) Alan - Original Message - From: Don Otknow donald.otk...@gmail.com To: time-nuts@febo.com Sent: Wednesday, April 06, 2011 11:05 PM Subject: Re: [time-nuts] Transmission line question Just for the record I meant pin as in the metal contact of a device, not a PIN diode. So I need the impedance the pin see's (that of the transmission line(s)) to be the same as the output impedance of the pin. Here's an extrapolation on the original question. If this is a high speed digital signal, with frequency elements ranging from say 133 MHz to 1GHz, then what I am really worried about, given the trace lengths (maybe 2 cm each way) is the high frequency components getting reflected or not sent down the line properly. If my source impedance from the the device is 50 ohms, the lines are each 100 ohms, and the terminations at each end are 100 ohms (probably AC terminated, but let's just say 100 ohms for simplicity), am I setting myself up for the best possible signal integrity? Here's a primitive diagram of the setup 100 ohm line 100 ohm line 100 ohm term. to gnd _100 ohm termination to gnd | | | 50 ohm source | Donald ___ 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] Transmission line question
Don, If it were a perfect world and the two 100 Ohm loads were perfect (no reactances), then you will have a complete transfer of power from the 50 Ohm source divided equally into the two 100 Ohm loads without reflections. BillWB6BNQ Don Otknow wrote: Just for the record I meant pin as in the metal contact of a device, not a PIN diode. So I need the impedance the pin see's (that of the transmission line(s)) to be the same as the output impedance of the pin. Here's an extrapolation on the original question. If this is a high speed digital signal, with frequency elements ranging from say 133 MHz to 1GHz, then what I am really worried about, given the trace lengths (maybe 2 cm each way) is the high frequency components getting reflected or not sent down the line properly. If my source impedance from the the device is 50 ohms, the lines are each 100 ohms, and the terminations at each end are 100 ohms (probably AC terminated, but let's just say 100 ohms for simplicity), am I setting myself up for the best possible signal integrity? Here's a primitive diagram of the setup 100 ohm line 100 ohm line 100 ohm term. to gnd _100 ohm termination to gnd | | | 50 ohm source | Donald ___ 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] Transmission Line Question
Well actually there's another level here which is that some of the lines are bidirectional data lines - each device at the end of the lines will occasionally drive these. However one of the devices (lets call it device A) can request a wait from the center device via a separate line so it should be possible to mediate issues for that device by just telling the center device to wait until the signals are stable. However, the other device (lets call it device B), with no wait request line, is probably not going to be as happy. But I think that (assuming that the data pins of the center device are high impedance while device B is driving the line and device B has a 50 ohm source impedance), then device B is going to see a 100 ohm transmission line in parallel with a 100 ohm termination, which should be fine, and at the other end of the transmission line (device A) a 100 ohm termination, which is also fine. Assuming the center device is high impedance, then there shouldn't be any weird reflections. Don Hi Don excuse me I was thinking RF :-)) That should be OK Though it depends what you are trying to do bus termination is usually slightly different to RF. At least you should not get nasty reflections from the ends like that. There may come a problem if you send a pulse from a 100 termination into the network. There will be a little diggle and reflection as it sees the 50 ohm pin as a small mis-match. But if driving out only from the middle I see no problem. (but then I might just be wrong :-)) ) Alan ___ 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] Transmission Line Question
On 04/07/2011 12:55 AM, Don Otknow wrote: Well actually there's another level here which is that some of the lines are bidirectional data lines - each device at the end of the lines will occasionally drive these. However one of the devices (lets call it device A) can request a wait from the center device via a separate line so it should be possible to mediate issues for that device by just telling the center device to wait until the signals are stable. However, the other device (lets call it device B), with no wait request line, is probably not going to be as happy. But I think that (assuming that the data pins of the center device are high impedance while device B is driving the line and device B has a 50 ohm source impedance), then device B is going to see a 100 ohm transmission line in parallel with a 100 ohm termination, which should be fine, and at the other end of the transmission line (device A) a 100 ohm termination, which is also fine. Assuming the center device is high impedance, then there shouldn't be any weird reflections. OK, now you have a bus. This should work, as long as the transmission lines are allowed to ring out such that it doesn't cause interference. Another solution is to have open-ended sides and then use Zener-diodes to clip out the reflections. See PCI for instance. Cheers, Magnus ___ 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] Oncore battery backup
To effectively charge a battery it needs a given amount of current for the plate area. Thats why larger batteries actually start in constant current mode. We are getting slowly but surely off topic. Regards On Wed, Apr 6, 2011 at 5:13 PM, Hal Murray hmur...@megapathdsl.net wrote: paulsw...@gmail.com said: The charger does not deliver enough current to effectively charge the battery set if its larger then the original design. As such the battery life is effected up to 50% and certainly the operating capacity. I'm missing something. I'd expect it to just charge slower. What's wrong with that? (as long as you are willing to wait longer and the unit doesn't overheat and ...) Actually, I'd expect charging slower to be (slightly) better for battery life. Consider systems that charge batteries from solar cells. They work fine on less than full bright sun. -- These are my opinions, not necessarily my employer's. 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. ___ 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] Oncore battery backup (answer to question)
Hi all, I had this quandary when using older VP Oncores that I bought at an auction. The on board rechargable batteries were defunct and the receivers did not have a connection to pin 1 of the header. I solved the problem by connecting a schottky diode between the battery terminal on the board and pin 1 so that I could put a 3 V Li cell on the mother board. That works very nicely. The diode avoids damage to the Li cell from the charging circuit. Rechargeable Li cells are very hard to find down here. Morris -- Date: Wed, 06 Apr 2011 13:53:40 -0700 From: WB6BNQ wb6...@cox.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Oncore battery backup (answer to question) First, which Oncore receiver is he using ? If it is the older series such as a GT+ or UT+ they are designed to have a Lithium 3 volt cell soldered onto the board. The memory draws 5 micro amps at 3 volts and 100 micro amps at 5 volts. There is an external connection available to provide the battery back-up off board with a caution of NOT exceeding 5 volts. The non rechargeable Lithium COIN battery has a discharge function that holds its voltage fairly constant right up until the end. They will last a very long time with just 5 micro amps of discharge. ___ 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 5V OCXO in 14DIP has about 1E-9 drift per day
Hi Pete; I bought 10 of these from you already. Im working on a converter that has 26M00 Hz in to 10M00 Hz out. Not sure if that is of any interest but Im putting it on the table. Greg On 4/6/2011 3:56 PM, Peter Loron wrote: Hello, folks. I'm the seller of the 26MHz OCXOs. Please reply off list if you are interested in some. Thanks. -Pete On 04/06/2011 08:58 AM, Oz-in-DFW wrote: Who is the seller? On 3/28/2011 1:40 PM, beale wrote: Just FYI, I'm not sure how this compares to other similar parts, but I'm seeing about +/- 1 ppb (1E-9) frequency drift per 24 hour period from one sample of the Pletronics OHM40480526, which I've had running for about 10 days now. It runs on +5V and after a warmup current of 250 mA for a few seconds, it draws about 60 mA steady state at room temperature. I'm driving the tuning voltage on pin 1 from a separate +5V reference to avoid variations due to heater current shifts. I use a simple resistive trimpot divider to set the voltage, this is not a GPSDO (yet :-). I'm sure most on this list have more refined tastes in oscillators than this one (and probably want 10 MHz instead of 26 MHz), but I thought it noteworthy because it is so cheap. These parts are currently available online for $2 each. I'm not affiliated with the seller. a few more details: http://www.bealecorner.org/best/measure/time/Pletronics-26MHz-OCXO-tuning.pdf http://www.bealecorner.org/best/measure/time/26MHz-osc-notes.txt ___ 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] Oncore battery backup
I did the same to extend the back up time of a couple servers, I used 2 car batteries because the UPS runs on 24 V. But be careful, aside for the live battery connection (I couldn't figure it out and learned that in the rude way, 220 V here), you can go into another problem: some UPSs, mainly the cheap ones intended for backup a PC lack the power dissipation capacity to run more than the internal battery discharge time, about 10 minutes at full load. If you connect an external battery to extend this time the power transistors can be cooked. I always wondered why these UPSs were not offered in several time ranges with the same power rating and this is usually the reason. Some time ago I used several UPSs manufactured by HP in a project and they had provisions for connecting external battery packs. They had the dissipation department well designed. Ignacio, EB4APL On 06/04/2011 20:25, Murray Greenman wrote: Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Just be careful though - in some UPS units the battery is live to the mains! The APC ones seem to be OK. Murray ___ 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.
