[time-nuts] HP 5335A Question
>The gate time on a 5335 can be set via GPIB. It can be set to some *very* long gates (well past 100 seconds). >When you do this, the data reported on GPIB does “stretch” to cover the added >digits. The problem is that there >are internal register overflows. The designers did not anticipate needing >quite so many bits. You loose the MSB’s >when you go to long gates. Compensating for this on a reasonable source is not >a big deal. > Bob Hi Bob, You need to use timed GO and GC commands (Gate Open and Gate Close), for > 1sec Gate Time. The GA command (Gate Adjust) is restricted from 1ms to 1 sec Gate time, so will not do the job. See manual page 3-29. One error correction: I replaced this 10µF Gate Time capacitor with a Tantalum type, 33µF, obviously, as these original 10µF already give about 4sec, so the 33µF are good for 12.5 sec, 10 digits. The designers very well designed two near inifinite counter chains inside the 5335A.. I got my wisdom from the hp journal 9-1980. They used a digital ASIC, called the MRC, multi-register counter, and it allows counting of the input signal and the time base, each 20 decades long. (see page 26). Therefore, the Gate Time could be 300 000 years long, before an overflow from the 10MHz time base would occur, and the result would theoretically be precise to 20 digits resolution plus 2 digits for the time interpolator. So you will NEVER loose any MSB information. The GPIB output also does not stretch its resolution , because in the manual, they have a fixed digits output format. On second read (pages 3-32 .. 3-34), it's not limited to 9 digits - sorry for the confusion - they reserve 14 digits for the mantissa, including sign and comma, so up to 12 digits can be transferred also, like on the display.. that means, also 11 significant digits over GPIB. I assume, they internally use about 13 digits for the arithmetic routines, maybe taken over from the HP pocket calculators. Frank Mit TravelXtra profitieren Sie von 5% Rückvergütung auf den Reisepreis – bekannte dt. Reiseanbieter und ein umfangreiches Reiseangebot wie im Reisebüro! https://email.freenet.de/reisen/index.html-weitergeleitete Nachricht Ende- Mit TravelXtra profitieren Sie von 5% Rückvergütung auf den Reisepreis – bekannte dt. Reiseanbieter und ein umfangreiches Reiseangebot wie im Reisebüro! https://email.freenet.de/reisen/index.html ___ 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] time poetry slam @ NIST
There's a really nice time-rap or time-poetry slam on NIST, which I want to bring to your attention: https://www.youtube.com/watch?v=e5VdQ1JCVHI=0s regards Frank ___ 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] HP3325B frequency jitter specification
Hello, I purchased an early vintage HP3325B synthesizer generator, from about 1988. Unit is working all right, as I were checking most of the verification items. I have locked the HP3325B to my HP5370B OCXO, and measured the stability of the synthesized frequency with the same 5370B. I recognized, that there's a frequency instability of about 0.003 Hz, which is about constant for all frequencies. At 10Mhz output, that would give a stability of 3E-10, that's really great, but at lower frequencies, e.g. at 1Hz, that would be 3E-3 only. This frequency stability of the synthesizer circuit is not directly specified in the manual. I assume, due to the high PLL division ratio at low output frequencies, relative to the nominal 30MHz VCO frequency, that this is a normal behaviour. So my question to the time-nuts list, is my instrument working properly, or should the lower frequencies be as stable (in relative terms) as the higher ones? Is there any adjustment, or maybe later circuit revision, that would improve the feedback loop to better stability? I only have the 1990 service manual (03325-90003) available, so I have no information about later changes. Thanks - Frank ___ 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] HP 10544A Repair
Hello Nigel , I already have done a similar repair on a 10811, described here: https://www.febo.com/pipermail/time-nuts/2012-January/062228.html A comparison of the 10811 manual, p. 8-16 and schematic, let me strongly assume, that the 10544 has exactly the same type of NTC inside. This NTC also has 100k @ 25°C, and 9k93k @ 80.0°C, 8k60 @ 84.0°C as the max. temperature. I chose the new NTC from epcos for an exact match of the R/T curve, and it's a precision type, 1% for R25 and B values , very reproducible, interchangeable and stable. The sample had been characterised by epcos at 25°C and 100°C, so R25 and B are extremely well in the middle of the spec, and I have 9 EA left... Maybe you need one.. if you are located in NL, that would be no problem. I did not find the 10544 manual, describing the correct procedure to correctly trim R4, but I assume you would 'simply' have to find a minimum or maximum in frequency, depending on the characteristics of the BT cut. But I also assume that this trimmer is not accessible from outside? Maybe difficult to trim , in this case. Frank ___ 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] My HP 5370B reads 6 nS out!
Pete, you do not specify, whether you use FREQ or T.I. when you use the averaging function. First of all, its OCXO can be adjusted to a few parts in 1e-9 only, as the trimmer is too unprecise. If the OCXO is running for several weeks already (idle state), its drift may be as low as a few parts in 1e-10 or better. If you put the instrument to FREQ mode, you may measure and the 10MHz of the GPSDO standard to about 2e-11 resolution, if you use 1sec time base on the 5370B. That should work also, if you directly measure 1pps, but you have to properly adjust the trigger level. Important: Don't use the 10k statistics, set the 5370A also to 1sec time base! Due to this low frequency, jitter should be higher, see specifications. You better do statistics by means of a PC, over GPIB. That will show the 30ps jitter of the 5370B, and the jitter of the GPSDO, on the order of 1e-10. You may also calibrate the OCXO of the 5370B this way, instead of that oscilloscope method. I strongly recommend Timelab from John Miles to do these measurements properly. http://www.ke5fx.com/timelab/readme.htm If you use the internal 10k statistics 10k, pay attention!! In this instance, the 5370B will do the frequency measurement in a different manner.. Not 100% sure, it will be a sort of a T.I. measurement, calculated to frequency. And that may produce a constant offset, if the internal T.I. calibration is not done properly. Look into the specs, its absolute T.I. uncertainty is 1ns only, although it resolves 20ps. You may check that behaviour, if you apply its own 10Mhz OCXO ouput to the FREQ input, and measure this frequency first on FREQ, 1sec. That should give nearly exactly 10MHz, 1e-10 jitter or deviation. Mine reads 9.999 999 999 85 MHz, for example. If you now switch to AVERAGE, SAMPLE SIZE 1, 100, 1k, 10K, you will see, that you will get big deviations as big as 0.1%, although it should measure its own OCXO to precisely 10.0MHZ. Mine reads 9,989 294 5 MHz, for example. That's due to the different measurement method, and should explain 6..7ns deviation on the 1pps signal also. This averaging should only be used with T.I.! Frank ___ 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] Trouble with Timelab and HP-5370B
Paul, the last two weeks, I made measurements with Timelab, updated to the latest version, to acquire data with my HP5370B. I have a standard NI GPIB card in one slot of my PC, i.e. no converter card. Everything is still working fine, as before with the old Timelab version. So I suggest, that your problem is located in your Prologix converter, which does not work correctly with Timelab. Frank ___ 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] Getting a 5370A tomorrow - How do i test it works
Bingo, welcome on time-nuts, also! Follow the manual, the first basic test is simply connecting the reference output on the rear to the input and measuring frequency and T.I. This lets you test function and base noise level (35ps)hat. If this test passess, the machine is running well in first instance. Max. input level is specified in the manual, 10:1 divder provided, so nothing critical.. RTFM , sorry! Then I'd inspect the interior, which oscillator is mounted. Think of buying an OCXO, 10811, if you find the simple XO - it's already more fun. Frank ___ 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] Yb clock - stability estimation procedure?
Hello time-nuts, The NIST paper describes the estimation of the stability of one Yb clock by simply comparing two equivalent clocks, and dividing by sqrt(2). This is obviously a common Metrological Practise, every time if something better is not existent or not available. This practise can be found everywhere in metrology: the comparison of Cs clocks of all National Metrological Institutes, the comparison of two Josephson Junctions in situ, claiming 1e-19 stability, the comparison of the old Weston Cells, comparison of the Primary Kilograms and stating a deviation of 1e-8, and so on. Those comparisons and stability estimations later become fixed definitions of the new definition of the unit, accompanied by setting the uncertainty to the stability estimation found before. That means, the next definition of the second, based on the Yb optical clock would be provided by a new value and definition for the frequency of the optical excitation, with an uncertainty of something like 1e-18, or the Allan deviation given in the paper. I wonder, what is the validity of this stability estimation, as the number of the different standards is very limited, and as there's always the probability, that two different clocks /standards may drift in the same direction. Also, there are always some physical effects left, which may (in alinear manner) shift the realization of the unit, let it be the magnetic field for a Cs clock, or an electrical filed for optical clocks. Does anybody know, where I can find the suitable standardized metrological regulation for that problem, i.e. under which circumstances such a logical step from estimation to specification is valid, and the associated statistical calculation framework? I have naively transferred this procedure to my artefact standards, i.e. 5 Vishay precision resistor , and 4 volt references. As those groups have very small annual drift and as I don't see a logical difference in comparison to the stability estimations of those quantum references, I also claim the stability of each artefact to be in the order of the found drift within the observed group. Now I would like to know, if I have overlooked something, and how to make a serious stability estimation by correct metrological/statistical calculations. Thanks Frank ___ 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] Yb clock - NPR Story on Atomic Clocks
Wow, this new type of clock is not even 100 times more longterm stable than the Cs fountain clock, it's even short-term stable as a H-maser, obviously. In the NIST article: http://www.nist.gov/pml/div688/clock-082213.cfm it's told, that the 1s instability is the same as the 400,000 sec or 5 days stability of the Cs fountain clock, ie. 1e-15..1e-16, I assume. Perhaps NIST can provide the Allan deviation already. Frank ___ 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] Yb clock Allan deviation
Hi, Andrew Ludlow himself was so kind to send me the Sciencexpress article, just a few minutes ago.. A pity that I can't post it here (2.2MB). The Allan deviation is nearly linear, following roughly a 3.2E-16/sqrt(tau) equation (calculated for a single clock). At tau = 1 sec, the instability is about 2e-16 increasing to 3e-16 at 3sec, then approaching the given equation. 1.6e-18 is attained at 25.000sec only. The interrogation time seems to be 1-5sec, still with many interruptions (25% time-outs). Further realistic improvements (more atoms, mitigation of several parasitic effects) may yield 1e-18 in 100sec in the future. Frank ___ 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] Typical HP 5370B resolution ?
Mark, The jitter is always around 35ps, typ. I think, you won't change anything on the latter parameter by re alignment, because it's given mainly by the jitter of the Time Interpolators and the zero crossing detectors. The alignment procedure mainly calibrates the absolute T.I. accuracy to 1ns, perhaps to 100ps in conjunction with this special switch box (don't remember its designation). Frank ___ 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] OT, looking for a good science forum
Hello Chris, I don*t know a good scientific forum, either. But I would also be interested, at least to have some ideas, what to do try out with those high precision gadgets, I have collected already ;-) For the question about low temperature measurements, I recommend sensors following a standard curve, which gives about 0.5K accuracy, or calibrated ones, which might give 0.1..0.2K for relatively low budget. Fuddling around with a temperature bath is not necessary, normally. At university, I have checked my set of sensors with liquid nitrogen, pure liquid oxygen and He(4). Today, liquid nitrogen might be accessible, where electronic manufacturing is done. (The gas is used for reflow process) I have used PT100 sensors down to pumped liquid nitrogen at 63k, and much less. A good 4 wire Ohm DMM with Offset Compensation is required, or a precise, switchable 1mA DC source. The most versatile sensor was a standard table Si diode, e.g. the DT-470 from Lake Shore; it works between 1.4K and room temperature, but requires a precise 10µA external current source, (easy and inexpensive to build on your own) but no offest compensation. http://www.lakeshore.com/products/Cryogenic-Temperature-Sensors/Silicon-Diodes/Pages/Model-Landing.aspx 1% grade NTCs are fine for temperatures down to -55°C. Frank ___ 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] Agilent 53230A Counter
Hello, Does anybody know details about the time interpolator in the 53230A? I did not find service manuals online containing the 'Theory of Operation'. The 5370 interpolator obviously was well-respected for its high linearity and low jitter, based upon the dual-vernier digital interpolator, but other T.I. counters containing analogous capacitor-integrators often suffer from non-linearities and higher jitter. As agilent obviously does not manufacture the 10811 OCXO anymore, what do they use instead, and from which supplier? Frank ___ 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] 5370B airflow
Hi, The perforated sheet belongs to the left, seen from front of instrument. Frank ___ 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] 5370 firmware hacking status report
Hi, the 5370 is capable of measuring up to 10s long time events or frequency/period with 10s gate time. (I.e. 2^39 * 19.53ps) Pressing 'external holdoff' activates external gating on 'EXT' input. Then you may apply a 10s long positive pulse from an external generator, with a few ms long pause, to the external input, getting 12 digits resolution. To have this longer gate time in firmware would be nice. Interesting would be to have even longer than 40 Bit arithmetic length by counting the overflow of the counter chain, and also, to get access to the full content of the arithmetic registers to calculate with higher precision externally. Or perhaps it is possible to realize a 'time stamp counter' on the 5370s hardware, to get zero dead time for T.I. measurements on 1pps comparisons. Frank ___ 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] Primary Time Standards
Hi, I think, the correct definition for a Primary (Time) Standard is not yet given here, yet. And I wonder, if there really exists an official definition, in form of a norm / a standard by BIPM. There should be one, does anybody know? I try to give some characteristics which have to be fulfilled all together, in the order of importance (think so): 1) A Primary Standard has to be accepted and defined by the Metrological Communitiy, i.e. by all the national standards institutes joining the BIPM. For time and frequency, its the CCTF which decides over the definition. A certain value is assigned to the Primary Standard, and an official definition is given. 2) A primary Standard is state of the art, it is currently the best one in terms of reproducibility. It must not be the most stable one (like Cs-beam/fountain compared to H-maser) What is accepted as a Primary Standard today, will be a Secondary one only by tomorrow, like the Rubidium, or even Quartz oscillators, which once were state-of-the-art Primaries. Which standard is better, can be measured and judged by comparing the Primary against the Secondaries, and by comparing an ensemble of Primaries against each other. 3) The known side effects or influence parameters (like magnetic field, pressure, temperature, particle motion, gravity, quantum effects, etc.) have to to be identified theoretically and experimentally, which means they are well known by magnitude and understood by a physical model. Experiment and theory have to fit. These side effects then can be effectively removed by either cancelling the influence parameter (e.g. in a Cs standard to zero the external magnetic field), or by evaluating the disturbance to calculate an upper boundary of the total deviation, or by making precise corrections to the output. 4) The Primary should not be an artefact (as the kilogram, currently), but should be defined and reproduced by basic physical effects, preferrably quantum standards, which can be reproduced everywhere in the universe, simply by a construction recipe, instead of sending an artifact around. So to answer Jims questions: A Rubidium standard is not a primary any more, because - it is less reproducible than Cs, due to the ~100 times higher susceptibility of the inner energy levels to magnetic fields. That means: External magnetic fields can be cancelled in both systems in the same way. But this residual field, produces a much smaller output deviation in the Cs clock. - The metrological community has redefined Cesium as the new primary many years ago, instead of the former Rubidium. The TAI is theoretically defined by the SI definition, whereby the UTC also accounts for the earth rotation by leap seconds. In theory the TAI / SI second is ideal (zero uncertainty) The TAI / SI second is practically realized by the complete ensemble of Cs Primaries in the National Standards Institutes worldwide. This real time scale is not perfect, as side effects on Cs are well known and cannot be eliminated completely. The reproducibility of the ensemble is around 2e-15 only.. But being the Primary Standard for the second, I think, this ensemble is simply defined to have zero practical uncertainty also, at least after the correction table is published. The trimming of the Cs clocks is intended for a controlled cancellation of those side effects, i.e. magnetic fields, but not for a sort of calibration! The different clocks principally cannot be adjusted against anything else, because nothing better exists at the moment. If the members of the ensemble all deviate from the total average in the boundaries of error calculations only, then they are Known Good. The statistical model of the complete ensemble gives an idea about the overall stability and reproducibility of the second, and also detects Bad clocks with systematic failures. On the other hand, it is not a good and accepted metrological practise at all , to tune one or more of those good Cs clock artifically close to the average. This would simply spoil the independance of the ensembles members. Today, the Cs is still the Primary Standard, although there might already exist more reproducible physical systems (e.g. Hg ion clock,???) The H maser is much more stable (short term), but not as reproducible (long term) as Cs clocks. That means, it is obviously not possible to get an ensemble of H-masers that close together by design only as it is the case with Cs. Therefore, H-masers cannot be Primary Standards. Frank ___ 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] GC-1000 Clock Cap Choice?
Hi Brooke, Our electronics designers (@automotive electronics supplier) have to take lot of care concerning voltage stabilizers, that the cap provides sufficiently low ESR, which electrolytics deliver only at much higher capacitance value; and a series resistor is introduced to limit loading currents of the Tantalum. Otherwise, the Tantalums might fail, either open, or they might burn, which already caused total damage of vehicles (Mercedes). I assume, latter aspect has been overseen in your device. This is the main fault modus of Tantalums. Electrolytics dry out over the years, especially when stored non-operating, Tantalums do not at all. You have to chose higher cap value and higher environmental temperature grade (= 105°C) for the ElCo, to get a reliable replacement. I commonly do not recommend polymer elcos, they have some further disadvantages, one being the price, the other (perhaps) being CN compounds in the polymer, which may be poisonous in case of fire. High cap value Ceramics are available since years, therefore , if price is no argument, I'd prefer to take them for values up to ~ 100µF; X5R ceramics should be good enough. With some luck, they (SMD type) fit to the existing pads on the solder side. Otherwise, you have to analyse the (misdesigned) circuitry for possible high pulse currents, and replace the bad tantalums by new ones in series with a limiting resistor. Several tantalums in parallel might also improve withstanding to current pulses. Check the tantalums datasheets. epcos has got some detailed application hints, as far as I remember. regards Frank ___ 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] GC-1000 Clock Cap Choice?
Can you clarify one thing for me: When I studied datasheets for these it looked like they drop 50% of their capacitance at a DC voltage of 10-20V. Doesn't that make them a so-so bargain for power supply bulk capacitance ? Poul-Henning, Pls. check the spec for dielectric material. X5R is automotive grade, interior applications (up to 85°C) ; X7R would be engine applications (= 125°C). Those ceramics don't have such high detoriation of cap vs. T and V. For example, Y5V is commercial application range and might have such problems. Frank ___ 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] GC-1000 Clock Cap Choice?
I have found that such high dielectric constant capacitors have other problems in some circuits. While the capacitance value is dropping, as much as 50% when you apply voltage, their physical volume is changing. They behave as piezoelectric transducers. I have used them inappropriately, and found them singing loudly. If that were to happen in a switching regulator, I would think the ultrasonic vibrations could do damage to the capacitor, the PCB, or the solder joints. -Chuck Harris We use ceramics widely in our applications, also switching power supplies and PWM circuits. Our customers always search intensivley for audible and visual problems before accepting our products, (we design instrument clusters). (X5R) ceranic capacitors did not yet pose any audible problems, but singing inductors did. It is also known, that ceramics'* piezo effect is problematic for audio amplifiers. I have to admit, that we do not use very high value caps; several µF is oK, higher values are either too expensive compared to ElCo and Ta, or too bulky. Anyhow, if our dear customers require us to avoid Tantalums for safety concerns, Ceramics are looked upon first. Frank ___ 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] GC-1000 Clock Cap Choice
Sorry, epcos sold ceramics business, and was itself swallowed by TDK. If looking for X5R and X7R cer caps, visit vishay, kemet, taiyo yuden, murata and others instead. This special material specification is well hidden at the official manufacturers specs. Those are high grade ceramic dielectrics, realtively cheap, not necessarily space qualified, only automotive, and especially not an exotic component anymore. If Tek had problems with tantalums in the past, they either have chosen bad suppliers (reliable / safe production is critical), or that was at the time, where the failure mechanisms were not understood well, or they have ignored application hints. Today, its possible to use Tantalums safely even in automotive applications, that goes for ceramics also. Its - as always - a question of component knowledge and reliability engineering. Frank ___ 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] My old new 53132A just arrived
Bonsoir Loïc, and congratulations for your new, nice device. You should order the T.Bolt from fluke.l on e...y, standard easy kit with power supply and antenna, just working fine, The LCD monitor is also quite handy. You may also order an LPRO 101 Rb standard from him, so you have always a very stable reference for a low price. Alternatively, you may get a receiver for the German DCF77 signal (I can see the transmitter every day from my work place), but its a real pain for such high precision TICs. I've got the predecessor of the 53132A, i.e. the 5335A - uses a similar time interpolation circuitry with 1ns LSD / 2ns resolution (jitter), giving 9 digits/sec. If you examine your TIC/counter, could you please verify the '132A counter specs, saying 12digits /sec, although LSD is 150ps, RMS resolution 300ps, which should give 10 digits/sec only. (My 5370B resolves 11digits/sec , but has 20ps LSD and 35ps RMS resolution.) I think the agilent people are cheating a little bit (compared to former HP). Anyhow, that's just for interest. Just have fun. Frank ___ 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] LCD monitor for TBolt
Dick, I also ordered an LCD monitor from fluke.l (beneath an LPRO Rubidium). For Lady Heather, do I have to add a switch between the monitor and the PC, or does the monitor have an additional RS232 port to feed through the PC communication automatically? Frank ___ 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] HP 5335A Option 040
Hi, there exist three manuals, 5335-90005 - Serial #2024A and below, 1980, preliminary pdf manual on agilent.com 5335-90021 - Serial #2224A and below, 1983, pdf from Artekmedia, very good scan for $7.50 5335-90044 - Serial #3154A and below, 1994, very good reprint from manualsplus for about 70$ If you don't have the latest device, Artek Media document is absolutely sufficient for description of Opt. 040, i.e. HPIB instruction set and schematics. (SW is different, also input amplifier / front end A12 and amplifier support A11) Btw.: I've got a nice 5335A with ser no 2820, Opt. 10, 30 , 40 (10811 oven, 1,3Ghz C-input - latest divide-by-64 version, and full front end remote steering). I've found out, that it definitely resolves 1ns in Time and Freq. measurements, in contrast to 2ns as stated by all the latest specs. in the manuals and all the HP catalogues. Gordon, and other 5335 owners - would you please check your instruments on that, to find out if firmware has changed later on, or simply if the specification is wrong? I get 11 significant digits over the bus and on the display, if I measure for 100s. I'd expect 12 digits for 1000s at least over the bus, as 14 digits are reserved for the mantissa (incl. sign and decimal point) but nothing happens. Anybody got an idea, how to get more digits, perhaps with undocumented commands? This counter potentially delivers nearly unlimited resolution, as the overflow is counted in many additional bytes, which I would like to read out. Thanks - Frank ___ 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] Faulty GPS SAT # 16 on Lady Heather
Once again, one of the 8 received satellites (#16) delivers no contribution to the time ensmble, although it got is over 40dbc strength. Lady Heather (beta 3.00) shows a hollow circle in the diagram, marked yellow in the list, and it has zero CLOCK BIAS and ACCU=0. Does anybody know, if that satellite is defect (e.g. Cs down), or if it has a special task, i.e. military purposes only? Frank ___ 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] HP 3420B calibration assistance
Hi Dick, I'm sure, I met the 3420B long time ago..that's a nice unit,.. but I do not have the schematics of the 3420B at hand, also did not find them on the agilent site, only the HP catalogue from 1970. The instrument - as far as I remember - compares the input voltage directly against 0-10V or 0-1V given by an internal reference and a Kelvin-Varley divider. 100V and 1kV input are divided first down to 10V and/or 1V. So you have to calibrate the linearity of the KV first, best done in the 10V range. Then you have to calibrate the 10V, 1V range, then the 100V and 1kV range. Using the 5440B only is the best way to handle this process, even better and faster than using an internal Wheatstone Bridge for linearity calibration. As far as I remeber, the missing card did not contain the necessary precision resistors for the Wheatstone Bridge, the user had to solder the Bridge on his own. Linearity of the 5440 is ~0.5ppm, sufficient for the 3420Bs KV. Range uncertainty is also superior. First two decades should be binary coded, so they should be calibrated each by a 1-2-4-8 sequence from the 5440B. The 3458A may be used for adjustments in the 100mV range. I do not remember the construction of the KV, especially how the adjustment from one decade to the other is designed. I.e. if the next lower decade is applied directly to the predecessor, or if an adjustment resistor is used (probable, if you mention 5 resistors per decade). Perhaps you may send me a scan of the KV, with the adjustment pots. I think, this should work if no additional decade resistor is used: Use the normal 10V range of the 3420B for linearity calibration. Start with the third decade, which cannot be adjusted, all its digits and lower ones to 0.0999X, which gives 100mV. Set 5440B for this assumed voltage of 100mV in the divider mode, freshly calibrated by 3458A, and set to operate. Adjust 10V range cal of 3420B , so that differential VM of 3420B shows Zero to 1µV or less. Set DVM un-sensitive and change 3420B setting to 0.1, ´1`being the first decade resistor which can be adjusted. Apply 100mV again, set DVM to sensitive, and adjust this resistors adjustment to Zero deflection. This calibrates the transfer from the third decade to the 2nd. Now, apply 200mV, 400mV and 800mV, and adjust the appropriate resistors of the 2nd decade at 0.2V, 0.4V, 0.8V settings acoordingly to Zero, 1µV or less. Set 2nd decade to 0.X, or to 0.X if the first setting is not possible. Apply 1V from the 5440B in the normal mode (not divided, control by 3458A) and adjust 3420B 10V range to zero deflection again, to have a more precise adjustment. Set 3420B to 1.0V and adjust the first resistor of the 1st decade to a Zero deflection, 1µV. This calibrates the transfer from 2nd to 1st decade. May also be different, if an additional decade resistor is designed in. Now calibrate 2V, 4V, 8V from 5440B against 2.0V, 4.0V, 8.0V of 3420B to Zero deflection to 2µV, 4µV,8µV, or better, if not too noisy. Now apply 10V, setting 3420B to 9.XV or X.0V, whichever is possible, finally adjust 10V range. Apply 1V, 100V and 1kV and adjust those ranges at the 3420B. As far as I remember, 1000V adjustment may not be not necessary, as this is accomplished already in the 100V range. Hope,this description helps. Frank ___ 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] HP 3420B..
Sorry, this post went to wrong mailing list. Frank ___ 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] I think I've become a Volt nut too.
Hi All, I have been a time nut for some time now. I think I've become a Volt nut too! I build the Silicon Chip magazine Voltage reference late last year but didn't have anything to compare it against so I bought a Fluke 732A DC reference standard. I there a group I can subscribe to that can help me with this? Can I coin the phrase; A man that has one DC Voltage standard knows how accurate his meter is, whereas a man with two standards is not quite sure! Regards, Nic VK2KXN VK5ZAT Hi Nic, please goto febo.com/pipermail/volt-nuts; John Ackermann opened a parallel mailing list to time-nuts to have a distinct discussion platform. I'm interested also, what kind of reference is used in the Silicon Chip magazine..is it LTZ1000 based? A single volt-reference would be sufficient, if it is calibrated peridiocally, i.e. if its drift rate is determined during at least 5 calibrations or so. In this case, a certainty of around 1ppm would be achievable. A 2nd reference would be better for keeping a working standard at home while the other is out for calibration. And an ensemble of 4 is good for averaging the VOLT below 1 ppm. Frank ___ 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] I think I've become a Volt nut too.
True, but there is always a probability that they all happen to be off one way. Quite a small probability, but not impossible. Sorry for the disturbing thought. In the case of the 732A, and the early 732B, this is in fact the case! Fluke mentioned, that all the 732A and the early 732B containing the Motorola reference had a systematic positive drift, whereas the later 732B, LTZ1000 based, showed a negative drift. Ref.: fluke.ae/comx/applications/deaver_msc01.pdf Therefore, for an ensemble of references, it is important to have a very good instant calibration (referred to a Josephson effect based standard), plus a determination of the annual drift rate by repeated calibration. Only then, statistical improvement by an ensemble makes sense. Btw.: Many artifact references cannot/define/ the VOLT: Such a definition by Weston ensembles drifted apart 10ppm between the different National Standard Institutes during the years. Only the introduction of the 'Josephson-Volt' in 1970 lead to the reproducibilty of the VOLT within 1e-9 worldwide. But the VOLT still is uncertain by 1e-7 in the SI system.. Perhaps next year this will change by redefinition of the SI-System (h, e, k, kg,..). Frank ___ 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] Finding precision resistors, tip
I've also got a huge collection of TK 1 precision resistors from defect Fluke and HP / dy standards.. Great for building volt-standards as precision references, dividers, and also well-aged standard-resistors. Got several from the 1960s. AThey show absolutely no ageing any more, (I suppose). On the search for new wirewound resistors, I found the 'econistors' at UK, Rhopointcomponents.com. They also deliver TK 0.3 metal foil type FLCY, all for convenient prices. Vishay - with some 'relationship' - delivered to me a small volume of Z201 - great ones, but budget consuming. Frank Stellmach ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] New request for HP 3458A info
Hello Dick, .. internal overload: 72 might be caused by a failure on calibration, as '72' might refer to the 'dcv 10V gain' (see calibration manual p. 5-6). Either an ACAL failed, caused by interrupting this process, or an attempt to calibrate the internal 7V reference has gone wrong, also because of interruption, or because of unstable / inappropiate external voltage reference. Please read out cal constant 72 by CAL? 72, on my instrument it's 1.00435... If you scroll the text to the rightmost, an additional string states if the calibration constant is valid. Then read out cal constant 2 by 'CAL? 2', that's the internal 7V reference. Should be betw0en 7,0V and 7,5 V, acc. to LTZ1000 datasheet, but typ. around 7,2V. It's 7,2165..V on my 3458A. Again, scroll the text righmost, if the constant is valid. If 7V ref constant is corrupted or out of range, a basic calibration might help. Btw.: Any clue about the history of your instrument? Best regards - Frank Stellmach ___ 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] 3458A info
Dick, did you already try an ACAL DCV, or ACAL ALL from the front panel? Maybe the false cal constants will be set correctly. In the calibration manual, its explained, which constants are set by atocal (and cured), and which one are set by basic calibration, requiring external standards (10 volt, 10kohm). I think, DAC Vos and 10V gain are set by ACAL. Frank ___ 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] OT: Basics of voltage calibration?
To John Ackermann! My recommendation for documents about DC-voltage-standards are the Fluke sites. Go to service/manuals, e.g.: http://www.fluke.co.uk/comx/manuals.aspx?locale=ukenpid=0 They still produce the best and most accurate DC calibrators and standards, and to my biggest pleasure, they recently scanned all manuals of actual and outdated devices. The manuals contain schematics, setup of complete reference system, and best read 'principle of operation'. For a complete system, you need the following devices / instruction manuals, just search for the product names and download: 1. Zener based Voltage References: 731A, 732A, 732B, 7000 (LTZ based, w.o. schematics) For the actual 7000 system, also search for the underlying UK patent GB 2 258 356 A, from John Robert Pickering (1993). The temperature hysteresis of the LTZ1000 zener reference is mitigated by a temperature cycling process. 2. Calibrators: 332A, 332D, 335D, (old devices, but very instructive for complete system); 5700A, 5720A 3. Kelvin Varley Divider: 720A (7 digits, 0.1ppm linearity) 4. Reference Divider: 752A (provides highly accurate transfers of 1:100, 1:10, 1:1, 10:1, 100:1 for the 5 cardinal DC points) 5. Null detector: 845A (see also schematics of 335D) To learn about precision resistors, goto vishay site, ultra high precision resistors, technical and application notes, datasheet: http://www.vishay.com/resistors-discrete/metal-foil/ Also: Zero TC Foil Resistor, Ten Fold Improvement in Tempertaure Coefficient, Reuven Goldstein et.al. Brian Kirby already summed up the other most important sources. Frank Stellmach ___ 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] OT: Basics of voltage calibration? Fluke manuals
Chuck, try '341A', this manual covers the 343A also. (different beta string only) I've got the 5100, 5205, 5215 manuals from their site, perhaps something comes close to your 5200. Frank ___ 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] OT: Basics of voltage calibration? Fluke manual 5200A
Chuck, I just have found the 5200A manual addendum here: http://us.fluke.com/usen/support/manuals/default.htm?prodcategory=OBS The others I mentioned are the power amps only. Fluke still scans on, so look for other manuals later. Frank ___ 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] Some pics of the Datron 491x DC reference cell
Bill, thank you very much for the schematics and the photographs! Using XP / firefox, I was able to retrieve the files with the given special link, and also very easily with the FileZilla Client. The most interesting part, i.e. the precision resistor circuitry, obviously resides on the bottom side of the ref board. Would be great to get a photo also from that side, as Datron made some efforts to get rid of strain and heat conduction effects. Best regards - Frank Stellmach ___ 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] Some pics of the Datron 491x DC reference cell
Bruce, good hint, I think you are right.. Then it's a custom specific R array, metal foil technolgy (S105 or similar) from Vishay, perhaps oil filled. Makes it very difficult to read the circuitry and design a replacement with discrete resistors. Frank ___ 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] Some pics of the Datron 491x DC reference cell
NB use the latest datasheet which has a corrected schematic showing the location and polarity of the parasitic diodes. Bruce Thank you, I already got that... When I used the first datasheet, I reversed the heater as there was no hint, just to discover those hidden parasitic diodes. I obviously did not damage the device (hope so), but sent that info to LT, and then they did the correction. Frank ___ 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] VRefs - I'm a bigger Voltnut than a timenut..
Hello, there's currently no easy way to convert a frequency into Volt, i.e. other than by cryo Josephson junction array or realizing Ohm by a Klitzing quantum hall effect device. Otherwise, FLUKE would have implemented that already in their Calibrators/Standards. They still rely on Artefact Calibration, i.e. ovenized longterm stable Zener References and Reference Resistors. The 5720A uses a stacked double Zener reference on a proprietary hybrid circuitry, giving 1-2 ppm/year stability, the 7001 and 732B use the LTZ1000 (Zener above BE junction), as the 3458A, the 732A uses the Motorola device (Zener below BE junction), and the elder 332D and 335D use similar, but less longterm stable references. The LM199, AD587 and I think also the Geller device may only be used as transfer standards, having poor longterm stabilities of 20ppm/yr. or more. Therefore, the LTZ1000 only may serve as a really affordable standard, i.e. below 8ppm longterm stability, for private use. I was lucky to get some LTZ1000 samples, and used the standard circuit from the LT datasheet for creating a small PCB. I purchased commercially available wire wound resistors (TK 3, 25ppm/yr) for the 5 necessary reference resistors and two OP07. Those resistors should give less than TK 1 and 1ppm/yr additional drifts. Compared to my HP34401A, the circuitry showed quite good short term stability below 1ppm, but shielding still has to be improved, as the LTZ1000 circuit is susceptible to external EMC disturbances. This Volt reference then costs less than 100 Euros/Dollars in total. I designed further circuitry (with TK 0.3 and TK 0.1 precision metal foil resistors from Alpha and Vishay, chopper amp, precision switches and Teflon insulated wires) to have the possibility for precision transfers of the 7,2V reference voltage to 100mV, 1V, 10V, 100V, 1000V level. Only then, a Volt Standard is complete. All this stuff will emulate or replace the commonly needed 732A (ref), 720A (Kelvin Varley), 752A (Reference Divider) and 834B (Null Detector). Got no time yet to finish and improve the system, and to do the repair on an old 332B standard, but would like to share my knowledge, if anyone's interested. Frank Stellmach ___ 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] VRefs - I'm a bigger Voltnut than a timenut..
@Bill Ezell: Well, I have the same motivation to invest time and money into precision. I started with metrology working in a German Airforce cal lab in 1980. We had all that goddie equipment, ie. a bank of Weston standard cells, the Fluke cal system, DCF receiver, a HP caesium standard, and so on. This cal lab was tightly associated with our PTB. In a secret lab they obviously made some tests on the new Josephson junction standard, as they transferred the Volt from this lab to our facility with a Fluke 731A, and they were very proud of that. From then on, the ppm quest never let me go. It's biggest fun for me to design standards on my own, not only to collect and repair old ones. I've already read about the Datron standards, but didn't know details, and that it's so sophisticated. It's inner principle of dividing the reference is identical to the Fluke 5720A, I think. Do you have a detailed schematic of the LTZ reference circuitry in the Datron? This cannot be found in the manuals of HP3458 or Fluke 7000. In Germany there is no big chance for getting surplus standards for a reasonable price. It's a pity.. Frank ___ 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] HP5370B - 10 sec Gatetime via GPIB
Hello, currently I'm testing frequency stability of an OCXO from NDK. The HP5370B is in the External Holdhoff External Arm mode. From a pulse generator I apply a 10sec ON, 100ms OFF TTL signal to the External BNC jack, so I get a 10 sec long gate time for averaging jitter effects much quicker than the built-in 1sec maximum gate time. Additionally, I send the results via GPIB to the computer for the usual statistics on the data. Now I tried to replace the external pulse by software. I simulated the pulses from the generator by leaving the External jack open, or short circuit it, and by reversing the trigger slope on that jack (comands SE0 / SE1). This works quite fine, as the trigger LED operates, but the counter does not produce a result, obviously because the arming signal is reset directly by the GPIB commands. I also tried some other additional commands, but nothing works. Has anybody got an idea how to program the HP5370B for a gate time up to the maximum of 10sec? Dr. Frank Stellmach ___ 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] manual 5370A
Hola Jose, Well, I have uploaded the 5370A manual of 42MB last October to David's site, and it seems to be still there: http://www.g8wrb.org/data/HP/ (circuit diagrams are stitched for plotting on A1/A0 plotter.) There's a picture on p. 252 (8-93) of this 'A' unit, 3 PCB spares can be seen, plus one additional space without a socket. Frank Stellmach ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
