[time-nuts] FIRST AID WHEN YOU BUY AN HP5065A
Dear friends, The first HP5065A were produced around the late years 60. Over time some flaws, related to engineering and the choice of components, are highlighted. The main ones are the following: - The capacitors used primarily on power lines of +20 Volts tend to lose the liquid inside and in the worst cases can corrode the copper circuit boards. - The power rectifier diodes heat up too much and tend to burn the fiberglass boards where they are mounted. Only one of these two issues has been partially resolved in more recent sn. The Capacitors These capacitors need to be replaced even if not visually appear to leak, this is to ensure the safety and reliability of your standard. Their characteristics are: 100uF 30 volts. You can also use higher voltages. The capacitors are mounted on the following boards and modules: - A3 C37 - A4 C1 - A6 C2 - A7 C3 - A8 C9,C10,C20 - A15 C8,C9,C10 Note: 001 option is not included in this list. Check on site. The problem of these capacitors has never been solved at the factory, even in more recent sn. It is however well check, especially with older sn, the capacitors C2 and C3 mounted on the chassis. These capacitors are connected to the rectifiers for leveling. A good way to test it without disconnecting them, is to measure, using a multimeter, the residual AC voltage in parallel to the capacitors. If the measured value is higher than 1 Volt probably the capacitors have lost their original characteristics. A symptom of this problem may be an off of the green light despite all measurements of “circuit check” appear correct. The Rectifier Diode The board A15, A18 or A2 in case of option 002 installed, uses some power diodes as AC rectifier and Power summing. These mushroom-shaped diode, heat lot and tend to burn the printed circuit on which are mounted. More recent versions, HP have replaced CR1-4 with a bridge rectifier mounted on the chassis. The update is very simple and for wiring, just disconnect the four-wire from A15 and attack them on the new chassis-mounted rectifier bridge (300V 5A). The other two diodes, of the same type are mounted on A18 or A2 if the option 002 is installed. The current will go through one of two diodes depending on whether the HP5065A will be powered by AC or DC and the heat generated will burn the card as in the case of the bridge rectifier. For standard A18 board see: CR1,CR2. For option 002 board A2 see: CR12,CR13. The easiest solution in this case is to install a star shape heat-sink on each diode. The service manual is an excellent tool to facilitate these simple actions. All these steps will help keep fit for a long time your HP5065A. Luciano www.timeok.it tim...@timeok.it Message sent via Atmail Open - http://atmail.org/ ___ 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] Price drop LUCENT/SYMMETRICOM Z3810AS, KS24361
I thought I would pass this along, the auction site seller of the LUCENT/SYMMETRICOM Z3810AS, KS24361 GPSDO's dropped the price by $25.00 The shipping is the same. Pretty amazing for shinny new old stock in the original unopened box No affiliation with the seller here, but I'm a happy buyer even at the higher price... shaking my fist and cursing that they are $25 cheaper at the moment. ;) The auction ID is: 221777430088 Max NG7M -- M. George ___ 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] IRIG-B audio decoder circuits and ICs sought
Responses interspersed below. Joe On Sat, 23 May 2015 11:54:53 -0400, time-nuts-requ...@febo.com wrote: Today's Topics: 1. Re: IRIG-B audio decoder circuits and ICs sought (Tim Shoppa) 9. Re: IRIG-B audio decoder circuits and ICs sought (Esa Heikkinen) 15. Re: IRIG-B audio decoder circuits and ICs sought (Hal Murray) -- Message: 1 Date: Fri, 22 May 2015 06:48:59 -0400 From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought Message-ID: CAJ_qRvZ+1Zep_Wx8k+o-qY=h3dxgdnlcpj20tuaw_ncffmi...@mail.gmail.com Content-Type: text/plain; charset=UTF-8 On Thu, May 21, 2015 at 10:22 PM, Joseph Gwinn joegw...@comcast.net wrote: The definition of good here is tenth-microsecond alignment between the 1PPS output of the decoder and the incoming IRIG-B12x signal. From: Tim Shoppa tsho...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought See for example the Truetime 820 decoder. Discriminators, One-shots, and Flip-Flops with pots to tweak the levels. Hmm. Interesting. URL? I'm not sure 0.1us is a reasonable expectation to get PPS from the 1kHz AF variant of IRIG-B. In 1950, it was millisecond only. But people now use it for microsecond level timing, and some COTS units do guarantee 50 nanoseconds one-sigma between IRIG in and 1PPS out. For instance, the TSync-PCIe, according to Spectracom. The trick is to phase-lock a 10 MHz TCXO to the 1 KHz IRIG-B12x signal, and use the decoder to deduce which 10 MHz cycle was the beginning of the second using a slow delay-lock loop. 1kHz AM IRIG-B was usually distributed across a site/range by telephone-type wiring using interspersed audio transformers for isolation in the long haul. It was used to drive simple displays that used 60's transistors or 70's SSI chips, and also recorded on parallel tracks on telemetry recorders. It's pretty cool because when playing back old telemetry tapes we would just use the same clock display we did when live, but when fed the audio from the recorder it showed us the time of recording. (In some cases in the 80's, I got to work with telemetry tapes that were 20 years old! Today they'd be 50 years old and you could still play it back while watching the display). Sometimes we would slow down the tape and on the pen recorders optimistically we could eyeball times with a resolution finer than the 10ms bit rate, but not better than 1ms. All true, but see above. -- Message: 9 Date: Sat, 23 May 2015 00:31:32 +0300 From: Esa Heikkinen tn1...@nic.fi To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought Message-ID: 555fa034.9010...@nic.fi Content-Type: text/plain; charset=UTF-8; format=flowed Joseph Gwinn kirjoitti: I prefer the DC level shifted variant of IRIG-B. I like and use IRIG-B00x too, but it only reaches a few meters, versus the required tens of meters. It's differential RS485-alike bus (with TS2100 at least) using 5V signalling level. It works easily more than few meters with twisted pair cable. For RS485 they claim more than kilometer if the speed is less than 100 kbit/s and here it's only 100 bit/s. So only tens of meters there's no problem. When I last used IRIG-B005, the vendor (Symmetricom?) said it was good for a few meters only on shielded twisted pair. I recall that the handling of shield grounds was strange. This was OK, because the signal was confined to one cabinet, and it worked just fine. But there was no mention that the B005 followed RS422 or RS485 or anything else. Nor does IRIG 200-04 say this, so I suspect that each company solves it differently. I think the AM was originally intended for transmitting IRIG-B wirelessly or analog tape/film soundtrack recording... That is correct. Yes, but I must have IRIG-B12x (Amplitude modulated 1 KHz sine wave), and the analog processing complicates things. I think that one best implements the IRIG decoder in a DSP chip. Yes and there will be delays. As long decoding delay remains constant, it's easy to compensate. In my implementation the decoding delay is 48 cycles (9,6 usec) and remains constant. Actually this is delay from rising edge verification to timer setting point. Yes. One designs such that the delays are predictable and constant. When decoding IRIG-B it's one second behind. Timekeeping functions are needed anyway. Data verification system comes as a side product. It's only needed to compare last received IRIG-B frame with timestamp of passed second. If times differ then there's bit errors
[time-nuts] Lucent REF0-REF1 GPSDO status?
Hi list, I've been lurking around for several years off and on, followed some of the much discussed LUCENT/SYMMETRICOM Z3810AS, KS24361 L101/L102, HP-KIO OEM GPSDO. As you know they have been on fleabay for more than half a year are now, currently down to USD125 plus SH. Not bad for new out of the box units, even if they are two decades old. It gives some want-one-itch I followed the first hundred or so posts here on the list on these units but got lost on the overall status. So I have some questions, apologize in advance if these questions have already been covered: 1 Is there a simple fix to get REF1 work standalone? 2 There where 50nS or so trim glitches/jumps reported initially, did they disappear after some operating time? 3 Did someone find a reasonably straight-forward way to get 10MHz out of REF1? For me, replies with three Yes's/No's are enough, although more info is appreciated. Thanks ___ 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] Divider circuit for Rubidium Standard
Bob wrote: The simple answer is that a biased fast CMOS gate will do a better job ADEV wise than your signal sources will. Maybe or maybe not, at tau ~1 second. Trouble is, as tau gets larger, the gate performs *worse*. The switching threshold of all MOSFET logic devices varies all over the place with temperature and supply voltage as well as random drift. At tau 10 or 100 seconds, these effects become more and more pronounced and xDEV gets worse, even if you take pains to keep the circuitry out of drafts. Gates are not a good way to square sine waves if you care about stability at longer tau. Most of what has been said against comparators on this thread are indictments of mistakes made in applying them, NOT deficiencies of comparators per se. I don't have the time nor energy to go into it in any depth right now, but: Properly applied, comparators can work better than pretty much anything else when the job is squaring a 1 to 100 MHz sine wave. A few Do's and Do not's: Do use a comparator with split supplies for the input section, so you can use actual ground as the reference voltage. Do not use inputs biased to mid-supply. Most especially, do not use separate voltage dividers to bias the two inputs, because the divider noise is uncorrelated and adds. If you must use inputs biased to mid-supply, use one good, low-noise voltage reference (LM329 or LM399) to bias both inputs so the bias noise is low and is common-mode (make sure to keep the time constants equal at the two inputs). But just don't use inputs biased to mid-supply in the first place. Do use a comparator with properly-designed internal hysteresis of a few mV (e.g., LT1719). Do use a good, modern comparator (again, e.g., LT1719) that was designed since chip-level thermal flow analysis became standard practice, to avoid the mysterious drift, instabilities, and metastabilities that comparators from the bad old days (mid-'90s and earlier) were famous for. Do not rely on a comparator to work with inputs from mV to 10s of volts. You wouldn't expect that with a logic gate, why in the world would you expect it with a comparator? Adjust the input level with amplifiers or attenuators to the optimum value for the comparator you are using at the frequency you are operating. A 5 or 10Vp-p sine wave at 10MHz slews fast enough at zero-cross not to need bandwidth-limited clipping amplifiers (a la Dick and Collins). Those techniques were designed for squaring audio-frequency sine waves, such as the mixer output(s) of a single- or double-mixer system. If you feel the need, you can increase the zero-crossing slope of the input signal by starting with a larger input signal than is optimum for the comparator in use and using diode clamps to limit the peak amplitude. There are many other best practices, but the ones above are enough to avoid the major application mistakes and have a reasonable chance of designing something that works to a high standard. Best regards, Charles ___ 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] Divider circuit for Rubidium Standard
Hi On May 23, 2015, at 12:37 AM, Charles Steinmetz csteinm...@yandex.com wrote: Bob wrote: The simple answer is that a biased fast CMOS gate will do a better job ADEV wise than your signal sources will. Maybe or maybe not, at tau ~1 second. Trouble is, as tau gets larger, the gate performs *worse*. The switching threshold of all MOSFET logic devices varies all over the place with temperature and supply voltage as well as random drift. At tau 10 or 100 seconds, these effects become more and more pronounced and xDEV gets worse, even if you take pains to keep the circuitry out of drafts. Gates are not a good way to square sine waves if you care about stability at longer tau. Yes indeed, if you have a clock that goes below 1x10^-15 at 1 second and drops linearly with tau from there, you will have issues. If you do not have such a clock. The gate probably will do just fine. The delta on the gate turns out to be a delta time (as in delta ns / ps / fs). As you go out in tau, the impact (parts in 10^whatever) of that time delta drops linearly with tau. So: what sort of clock (that you have) are you proposing to look at? Bob Most of what has been said against comparators on this thread are indictments of mistakes made in applying them, NOT deficiencies of comparators per se. I don't have the time nor energy to go into it in any depth right now, but: Properly applied, comparators can work better than pretty much anything else when the job is squaring a 1 to 100 MHz sine wave. A few Do's and Do not's: Do use a comparator with split supplies for the input section, so you can use actual ground as the reference voltage. Do not use inputs biased to mid-supply. Most especially, do not use separate voltage dividers to bias the two inputs, because the divider noise is uncorrelated and adds. If you must use inputs biased to mid-supply, use one good, low-noise voltage reference (LM329 or LM399) to bias both inputs so the bias noise is low and is common-mode (make sure to keep the time constants equal at the two inputs). But just don't use inputs biased to mid-supply in the first place. Do use a comparator with properly-designed internal hysteresis of a few mV (e.g., LT1719). Do use a good, modern comparator (again, e.g., LT1719) that was designed since chip-level thermal flow analysis became standard practice, to avoid the mysterious drift, instabilities, and metastabilities that comparators from the bad old days (mid-'90s and earlier) were famous for. Do not rely on a comparator to work with inputs from mV to 10s of volts. You wouldn't expect that with a logic gate, why in the world would you expect it with a comparator? Adjust the input level with amplifiers or attenuators to the optimum value for the comparator you are using at the frequency you are operating. A 5 or 10Vp-p sine wave at 10MHz slews fast enough at zero-cross not to need bandwidth-limited clipping amplifiers (a la Dick and Collins). Those techniques were designed for squaring audio-frequency sine waves, such as the mixer output(s) of a single- or double-mixer system. If you feel the need, you can increase the zero-crossing slope of the input signal by starting with a larger input signal than is optimum for the comparator in use and using diode clamps to limit the peak amplitude. There are many other best practices, but the ones above are enough to avoid the major application mistakes and have a reasonable chance of designing something that works to a high standard. Best regards, Charles ___ 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] TymServe 2100 1995 Issue - A Kludgy Fix
descoubes kirjoitti: I am working for HEOL DESIGN company, and we are currently investigating this TS2100 1995 bug. We have developped the N024, a clone of Trimble ACE III receiver (which is mounted inside the TS2100). They are many issues with the TS2100-ACE III internal protocol, and we have good hopes to solve it out by N024 software. Thanks for the information. Of course it would be nice to get the internal GPS working too. I was planning that rude solution could be to cut off the GPS serial port lines and use only it's PPS output so that TS2100 sees it as external PPS. This would require changes to TS2100 motherboard (PPS should be routed so that it's feeded to Ext_PPS input). That hack would throw away anything else than PPS but will keep the unit in time as long there's no interruption on GPS reception. Of course this means that the time, leap second data etc. must be set manually (like now) but the worst thing is that there would be no way to see any GPS status anymore. If it loses signal, there will be absolutely no indication. Another solution could be like this, but with added microcontoller. Also in this solution only the PPS is routed to TS2100 directly. GPS serial port would be routed to microcontroller instead. Microcontroller would handle the GPS time decoding and follow TS2100's time from IRIG-B signal. If it notices that TS2100 time is gone wrong, it could correct the time and leap second settingc etc. by using TS2100 console serial port. If TS2100 follows PPS correctly, this should only happen in the startup. This would bring back the automatic time setting but this requires very much work. Also in this solution the main trouble is the loss of GPS status. To fix this, iw could be possible to share the TS2100 LCD display so that also TS2100 LCD port is routed thru the microcontroller, which could alter the LCD data from TS2100 before sending it to LCD. In the main display the 2nd line of LCD shows always Datum Tymserve 2100, which is kind of useless information. So the microcontroller could filter that away and write the GPS status there. TS2100 LCD looks like standard HD44780 and it would not impossible to capture the data, alter it and send to display. Best regards, -- 73s! Esa OH4KJU ___ 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] Sine-square widget
John, On 05/22/2015 10:35 PM, John Ackermann N8UR wrote: Referencing the conversation about squaring circuits, I realized the T2-Mini board (intended as a tiny PIC-based PPS divider) can be repurposed into a very nice squarer. It has a slightly modified version of the Wenzel squarer and by simply installing a jumper wire instead of the PIC chip (pin 2 to pin 3 of the PIC socket), it will put a nice TTL-level, squared, version of the input signal on the output connector. The T2-MIni manual is at http://tapr.org/~n8ur/T2_Mini_Manual.pdf and you can order the semi-kit (all surface mount parts installed, connectors provided but not installed) at http://tapr.org/kits_t2-mini.html This is how I have modified my two TADD-2 and mentioned multiple times here on the list. The improvement in measurement performance is noticeable and when using my DTS-2070 it is very clear that you move from signal-limit to counter-limit. 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] Divider circuit for Rubidium Standard
I was the OP and the reason for the whole exercise is to take a Rubidium standard that only outputs 1pps and modify for use as 10MHz. With some research there is a 20Mhz source onboard, issue is the sine is not very clean at 20MHz (60MHZ as well, much cleaner and may be worth inputting straight to logic). Thus the need for a divider circuit to divide down to 10Mhz. The purpose is to create a bench standard for hobby use and a external 10MHz reference for a HP 53131A Pics of the waveforms (not my pics but my results are the same) http://1drv.ms/1HB0Nwn -=Bryan=- From: kb...@n1k.org Date: Fri, 22 May 2015 17:31:47 -0400 To: time-nuts@febo.com Subject: Re: [time-nuts] Divider circuit for Rubidium Standard Hi What is your objective? Put another way: 1) How clean is your sine wave source? 2) What frequency (or range) are you trying to convert? 3) What level range are you trying to work with? 4) What is it going into (how clean is the next stage)? If you have an optical fountain that is good to 1x10^-15 at 1 second, and you are trying to map Pluto with a radar in your back yard, the answer will be a bit different than if you are starting with a surplus OCXO and trying to drive a 5334 :) Bob On May 22, 2015, at 4:27 PM, xaos x...@darksmile.net wrote: After reading the posts on this subject I have a question. First, in my experience I used a rather simple circuit made from diodes used as limiters and a transistor feeding a logic inverter. No AGC. So here is my question. What is the proper circuit to use? I'd like to do a PSPICE and check things out followed by a prototype. I got that a comparator is out, etc. Cheers, George H. N2FGX On 04/26/2015 06:51 AM, Bryan _ wrote: All: Picked up a FE 5680B from Ebay awhile back. Appears to work fine, but is limited to a 1pps output. However there is a point on the PCB that's documented that has a 20Mhz output. There is actually a clean 60Mhz output as well. http://www.ebay.com/itm/FEI-fe-5680b-rubidium-oscillator-With-1pps-20mhz-output-ONLY-10mhz-NEED-to-MOD-/291419889143?pt=LH_DefaultDomain_0hash=item43d9fa9df7 I would like to tap this 20mhz output and feed it to a divider/buffer circuit for a 10Mhz output at 50ohm. Can anyone recommend a good schematic for such a purpose. I was looking at the project from David partridges web site http://www.perdrix.co.uk/FrequencyDivider/index.html Cheers and thanks in advance. -=Bryan=- ___ 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.
