hybridfree/eevblog-posts huggingface dataset:
LIGO - Measurements at 10^-21 - Page 1
Forum section: electronics / general

author: ch_scr
author_rank: Frequent Contributor
timestamp: December 13, 2021, 01:01:20 pm
content: The LIGO experiments are really one of the great scientific frontiers of our time. Something measuring effects that small surely has a place on a metrology board?It's like measuring ppm's are child's play in comparison! Until now there was this video from a few years ago, that gives a broader scientific view of the subject:Now there is this new video:which gives a shorter scientific introduction followed by the "Hacks at LIGO",where they describe few select arcane problems and solutions they have come up with, most interesting for the more technical minded.I found the "matlab to linux kernel code converter" they developed to allow easy deployment of feedback loops without using DSP's on standard hardware most interesting.
BK Prescision 2841 - Page 1
Forum section: electronics / general

author: Traceless
author_rank: Frequent Contributor
timestamp: December 09, 2021, 10:30:14 pm
content: I just stumbled upon a demo video (link below) of theBK Precision 2841resistance meter, and was pretty impressed. This seems to be *really* useful for tracing shorts. One thing that was odd about the video though was aweird jump-cut around 1:30. I'm not sure if they had an outtake or try to cover something up. Does anyone own one of these and can report if resolution and speed really are as good as it seems in the video? Secondly are there DMMs that can keep up with the BK Precision 2841, or do I really need to get a dedicated resistance meter for that kind of performance?

author: bob91343
author_rank: Super Contributor
timestamp: December 09, 2021, 10:44:13 pm
content: My HP 3456A does a good job. So does the GR 1658 and, to a lesser extent, the HP 412A.You can also cobble up a 4-wire Ohmmeter from an LM317; do some Googling.

author: thm_w
author_rank: Super Contributor
timestamp: December 09, 2021, 10:56:08 pm
content: If its a short, use a high current power supply set to a low voltage and a meter in mV range or less.A 5.5 digit multimeter should be plenty, a basic 0.1mV resolution DMM can often work as well.Although agree this is nice resolution. On the 20mR range this is driving 1A at max open circuit of 5V, 0.1uR resolution, 200k counts.

author: Traceless
author_rank: Frequent Contributor
timestamp: December 09, 2021, 11:19:59 pm
content: @bob91343, @thm_w, thanks for the feedback. Currently I only own a pretty budget 4,5 digit bench meter (55k counts). It supports 4-wire measurements but the update speed is slow and resolution in resistance mode is worlds away from the BK above. The high current PSU/mV range would probably be the better approach with my meter. I'll also take a look at the LM317.

author: Kean
author_rank: Unknown
timestamp: December 10, 2021, 06:23:31 pm
content: FYI the BK Precision 2841 is a rebadged Tonghui TH2515 DC Resistance Meterhttps://www.tonghui.com.cn/en/product_396.htmlYou can buy the TH2515 for approx 75% of the BK list price, but of course you will get international warranty & support if buying from a proper BK distributor.

author: Traceless
author_rank: Frequent Contributor
timestamp: December 11, 2021, 11:16:41 pm
content: @Kean, thanks for the tip, it is nice to be able to save 400 bucks on this one. I'm not even sure if BK has official support here in Germany. Mousersays it was not available in germany. So I'd might have to import without support even if I'd go for the BK model, in which case the Tonghui would surely be the better option.Farnellseems to deliver the BK model in Germany though - for around 1600 € (~1800 USD) + shipping.
3325A SYNTH/FunGen connectors, ampl CAL  - Page 1
Forum section: electronics / general

author: jonpaul
author_rank: Super Contributor
timestamp: December 10, 2021, 03:26:48 pm
content: Bonjour a tous,Needed to check AC V CAL of my Keysight 34465A DVM, my best choice was 1982 HP 3325A synth. as I have no Fluke 5100 etc CAL.Unearth the HP unused for about 15-20 years...turns on ...BLANK DISPLAY!By the time I found the bound loose-leaf orig serv man, and powered on off a few time...IT WORKED!Opened up, super clean, gold plated boards made in USA 1982 clean as new!After self check, warmup and CAL, seems 100%!So, checked sine results at 1 mV ...1V RMS and 1 kHz..300 kHz.All my ACV meters, HP 400 FL, HP 3400A Fluke 8920 and 8921 TRMS. also with Fluke 8842A DVMconsistent results with error ~ 1.0033 for a 1.000 VRMS 3325 setting.1/ The amplitude adjust procedure in the service manual seems to be complex. Anyone ever CAL the amplitude on 3325A?2/ These seem prone to flaky Molex or RCA connectors used for interboard connections. Exercise them, contact cleaner, connector plus etc?Appreciate any experience or any tips.Many thanksJon

author: Simon
author_rank: Unknown
timestamp: December 10, 2021, 05:42:41 pm
content: https://www.eevblog.com/forum/testgear/keysight-officially-lost-the-plot-dont-buy-if-youre-a-hobbyist/msg3866078/#msg3866078
Repair: Fluke 720A KVD - broken decade-A switch - Page 1
Forum section: electronics / general

author: meandeev
author_rank: Regular Contributor
timestamp: December 09, 2021, 09:07:51 pm
content: 3 years ago I bought a Fluke 720A at a fair price and discovered that it had a defective "A decade"-switch (as usual?) as I wrote inthis message.So I put it in the corner until I had some time. Some days, months later ...I opened the switch and found a broken feeder and a broken shaftThe feeder was easy: I took a usual washer and thinned the outer diameter.Then it was glued together (with UHU Endfest 300, Araldite or something similar):(continued on next message because of image restrictions)

author: meandeev
author_rank: Regular Contributor
timestamp: December 09, 2021, 09:09:39 pm
content: (continued)The shaft was not so easy, but it´s also possible.Here are my measurements:The shaft itself (please forgive my handwritten unprofessional drawing):The angle (but I used 77° later, it fit´s much better)I used POM and a lathe to create a first blank shaft.Then I used this "tool" to create the flattening for the feeders with the help of grinding paper.Glued together with the help of a different "tool":Why I used 77° for the shaft, although I measured 75°?Here you can see 75° (rotating left and right) - you can see the feeder is between two contacts (ok there is also an additional air gap between shaft and feeder, so this prototype isn´t usable also because of the second problem)Here you can see 77° (rotating left and right), it fits much better!All in all I created at least 8-10 blank shafts on the lathe for testing the dimensions and angles and because of the lack of repeatable precision of handmade things.If you hand grinding the shaft maybe 2/10mm too much then you can throw away the prototype.But in the end I have now a fully functional Fluke 720A KVD!best regardsRonny

author: TiN
author_rank: Super Contributor
timestamp: December 10, 2021, 12:27:24 am
content: Reminds me ofpast experience too. Have few 720As in queue to fix as well.

author: SilverSolder
author_rank: Super Contributor
timestamp: December 10, 2021, 01:19:40 am
content: Nice! Sometimes you have to make stuff the hard way.At least you didn't have to go as far as these guys:
Elliott 8096 transistor curve tracer - Page 1
Forum section: electronics / general

author: David Aurora
author_rank: Frequent Contributor
timestamp: December 12, 2021, 02:24:29 am
content: Anyone got/had one of these, or even better, schematics/manuals?Just picked this one up at a deceased estate clear out, absolutely immaculate inside but clearly mid-repair as it was missing the power cable and some internal screws so someone was definitely in there fiddling at some point (the guy was a 96 year old tech/collector/hoarder so everything was pretty well looked after).After a good clean out and check it’s basically kind of running, but definitely has a few quirks. So before I start fiddling with trimmers to figure out what they do I thought I’d see if anyone else has one (Google turns up nothing)
1n4571 vs 1n4574 - Page 1
Forum section: electronics / general

author: cnt
author_rank: Contributor
timestamp: November 25, 2021, 07:03:02 am
content: I decided it would be fun to see how stable I could make a zener voltage reference. I have no actual needs though so I'm not going to spend a ton of money on it (famous last words for every project I've ever done). I figure I'll keep it at work as a really boring desk-toy and occasionally measure it when I have the nice meter out.I think a 1n4571 fits the bill of only 5$ and fairly good but I see the 1n4574 the same "typical" characteristics but worse, worst case. It's also 20$. Are these the same just binned around the specified current? Can I tweak the diode current up and down while adjusting the temperature to find the TC=0 point and just set it there? Also they come in a -1 option with an "internal metallurgical bond". Is that good? Do I want that?Are there other diode options that are better drift and Tc per dollar?

author: Kleinstein
author_rank: Super Contributor
timestamp: November 25, 2021, 08:13:42 am
content: The difference between the diodes is bining and maybe also more accurate testing. Chances are that the good ones end up as higher grades and the chance to find a good one (zero TC at 1 mA) is relatively small. In most cases one will be able to get zero TC at a different current (e.g. 0.2 mA or 2 mA). A lower current would naturally lead to more noise and a higher current may be more effected by the series resistance and thus a slightly more critical resistor to set the current. With the low current to start with this would be less of a problem.With the different related types also for higher / lower current binning may be even more complex.The classical series of temperature compensated zener diodes is the 1N821 ... 1N829. These are for higher current (7.5 mA) and thus usually lower noise. A down side is that going to higher current with a 1N821 can become tricky. So there there is may very well happen that zero TC is at too high a current to be useful. As far as I have heart from 1N825 on it is usually possible to get zero TC at a reasonable current.With these diodes there is anyway some 2nd order TC and for a really stable voltage over a larger temperature range (e.g. +-5 K or more) a stabilization of the temperature would be the logical way to go. With a good temperature control the TC is no longer that critical and some 50 ppm/K (e.g. 1N4571 or 1N823) could be usually good enough.
Siemens resistor decade, Oldie  Restoration. - Page 1
Forum section: electronics / general

author: Martin.M
author_rank: Frequent Contributor
timestamp: November 12, 2021, 01:46:56 pm
content: Siemens Oldie: R Decade 0 to 111,111 Ohm, wired with Manganin ( Isabellenhütte )

author: Martin.M
author_rank: Frequent Contributor
timestamp: November 12, 2021, 01:49:50 pm
content: here is the picture from the problem inside.tested with a needle. Begin of the cable = Mp0Mp0 to Mp1: closedMp0 to Mp2: open

author: NWerner
author_rank: Contributor
timestamp: November 12, 2021, 11:04:40 pm
content: I have a siemens&halske unit which uses same switch technology. Resistors look similar as well.In my unit manganin wire was connected to copper wire (at least for thinner wire) for easier interconnections.This manganin-copper connection is probably a weak spot.

author: Martin.M
author_rank: Frequent Contributor
timestamp: November 13, 2021, 05:50:49 am
content: the green color between the both test point is oxidation ( Grünspan ).Manganin is a copper mixed with around 15 per cent mangan, so easy to solding.Not the same then the tungsten mixed wires for heaters, they are horrible in connecting.If you have a repair, I have a NOS roll Isabellenhütte Manganin 69,7 Ohms/m, made 1985 = aged.

author: Vgkid
author_rank: Super Contributor
timestamp: November 13, 2021, 10:21:08 am
content: That is a nice decade, shame about the resistor. Thankfully manganin is solderable, so you can solder the two halves together.

author: Gyro
author_rank: Super Contributor
timestamp: November 13, 2021, 10:37:42 am
content: It's nice to see Vaseline being specified as a contact lubricant for sliding contacts in decade boxes. I've always found it really good but it's good to see a manufacturer recommendation.

author: Martin.M
author_rank: Frequent Contributor
timestamp: November 19, 2021, 07:38:00 am
content: fascinating:the oldie is using abs. ohms instead of intern. ohms

author: Neepa
author_rank: Regular Contributor
timestamp: November 20, 2021, 08:38:56 pm
content: Quote from: Gyro on November 13, 2021, 10:37:42 amNo chance of those switch contacts tarnishing even if it's the 9th millenium and the 186th service cycle for the box.
10V 40mA DC Calibrator in Elektor Magazine - Page 1
Forum section: electronics / general

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: December 05, 2021, 06:18:06 pm
content: https://www.elektormagazine.com/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001https://youtu.be/i8ZxOXWNTnU

author: Kleinstein
author_rank: Super Contributor
timestamp: December 05, 2021, 08:16:43 pm
content: I think there could be a potendial problem with the protection: The clamping at the output may be sufficient if the circuit is power powered, but with no power or a lower voltage (e.g. during turn off / turn on), the ouput votlage can exceed the supply of the chips. One may still get away with this - depends on the chips.Given the price for the 2 ppm/K resistors it is a rather strange way to generate the +-10.5 V. The simpler choice would have been 3 x 7 V ref in series and than just get the center right. I guess 3 x LM399 would have been easier.

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: December 06, 2021, 05:31:59 am
content: One can use LT5400 resistor matching network, its not expensive. That's what is done in SRS DC205, which has a very similar design.
Is a heatsink desirable for a Trimble Thunderbolt? - Page 1
Forum section: electronics / general

author: elroy
author_rank: Regular Contributor
timestamp: November 22, 2021, 08:36:02 pm
content: One friend has suggested mounting my Trimble Thunderbolt (~20 years old, in metal case) on a heatsink.Another, however, says that isn't a good idea. The Thunderbolt runs a heater to achieve an intended operating temperature, and drawing heat away with a heatsink will cause the heater to run more often.The second argument is sounding more plausible. Is it?

author: mendip_discovery
author_rank: Super Contributor
timestamp: November 22, 2021, 08:54:09 pm
content: I did see some chatter about this before only the other week. What you are after is temp stability. So first I would place it inside an enclosure to reduce airflow causing warm and cold spots, give it some ventilation as overheating can be just as much of an issue as cooling.

author: edpalmer42
author_rank: Super Contributor
timestamp: November 22, 2021, 09:09:40 pm
content: Quote from: elroy on November 22, 2021, 08:36:02 pmThe Tbolt has an OCXO which maintains its interior at a constant temperature. However, there's nothing that needs heatsinking.Your friend that's recommending a heatsink might be thinking of the various small telco Rb standards. TheseDOneed a small heatsink.mendip_discovery's point about temperature stability is a good one. Temperature changes caused by drafts, sunbeams, or HVAC cycling will have an effect on the outputs, although the processor will do its best to minimize those effects.Ed
calibrating a compensator - Page 1
Forum section: electronics / general

author: NWerner
author_rank: Contributor
timestamp: November 05, 2021, 07:41:48 pm
content: Hello,I would like to calibrate a compensator (more specifically a Siemens &Halske Kaskadenkompensator).I am mainly interested in the lower voltage range (<100uV) where my DMM - a Datron 1271 - is of little help. I cleaned contacts,checked operation and made myself a fairly stable constant current source to operate it.I have however no idear about how to calibrate this thing. If I remember correctly a inductivevoltage divider can be used. But how? Specifically I can't understand how to deal with phase errors andI can't make much sense of the literature.Thank you for advice.Norman

author: 1audio
author_rank: Frequent Contributor
timestamp: November 11, 2021, 06:00:54 am
content: It looks similar to what was called a potentiometer in the first 1/2 of the 20th century. Not what potentiometer connotes today.They were used with gavanommeters.for accurate voltage measurements. Very similar to Kelvin Varley dividers but with extra stuff. Calibration would be similar to calibrating a KVD. And not a simple process. Yours looks very nicely made.

author: NWerner
author_rank: Contributor
timestamp: November 11, 2021, 09:26:37 pm
content: You are right - at the heart of the compensator is a potentiometer. My unit is from the 60s and was in good shape.I figure that it can be considered a 4-wire resistor with largish lead resistance. As I am mainly interested insmall output voltages I suppose that AC excitation is needed. Coincidently there is a RT-18 inductive voltagedivider sitting on the bench and it would be a shame to let it sit there unused.After some reading about thermometry bridges I came up with the attached idea/concept

author: 1audio
author_rank: Frequent Contributor
timestamp: November 12, 2021, 04:58:58 am
content: What are you trying to do with it. Potentiometers are only meant to have zero current from the tap point. Any resistance or leakage from the tap to anything degrades the accuracy. The Ratio transformer is different and possibly more accurate at low voltage, just doesn't work for DC.
Which PCB to base LTZ1000 build on?  - Page 1
Forum section: electronics / general

author: aronake
author_rank: Frequent Contributor
timestamp: November 20, 2021, 10:57:10 am
content: Hi all electronics superstars!I have been reading though lots of info about LTZ1000. There are numerous PCBs used.I plan to build a LTZ1000 reference. Of main importance is the 7V direct output. If the circuit also can output 10V thats not really needed but could be nice too.Intend use is as a learning project, to see how multimeters drift over time and look into low noise measurement set-ups. Something with a balance that score reasonably well in all areas of low noise, low temperature coefficient and low long term drift.Targeted budget around 200 to 300 USD.Which of all PCBs out there would you recommend to make the build on? Preferably a PCB that can either be ordered ready made or for which gerber files can be found.

author: Oldtestgear
author_rank: Regular Contributor
timestamp: November 20, 2021, 12:29:24 pm
content: I used the 3458a reference board design recently. Worked well for my purpose & readily available from OSHPARK in the USA. There are plenty of options to choose from.It is useful to decide what your intended application is before buying the (very) expensive resistors intended for this design. It may well be possible to use lower spec. resistors if the operating temperature is restricted to a few degrees around a set point. It will not be "perfect" but could do the job. Others will probably disagree with this comment. I may decide that it is total rubbish after I have done a lot more testing & built one or two more.It may be worth asking ADI for samples of the LTZ1000. They were quite willing to sample me.CheersPhil
Proper cleaning of contact wipers of precision decade resistor box.  - Page 1
Forum section: electronics / general

author: NaxFM
author_rank: Regular Contributor
timestamp: December 01, 2021, 05:37:01 pm
content: Hi everyone, I scored a 11k to 0.01 ohms decade resistor box for 60 bucks.Aside from a crooked knob and slightly bent metal it's in really good shape, I already opened it and all the resistors are wire wound.The problem is that the wipers need cleaning.I already heard about the wonders of deoxit and I plan to use it, but what should I do with the shmoo which covers the wipers?Should I clean it first with isopropyl alcohol or I just go ahead and spray the deoxit?Sorry if this may seem a silly question, but this is the most precision equipment I own and I really don't want to screw up.

author: bob91343
author_rank: Super Contributor
timestamp: December 01, 2021, 05:50:04 pm
content: Do not cllean the contacts. They need to be exercised, that's all. Cleaning will destroy the precision of the values, especially the extreme ranges. On the high ranges, there will be leakage and on the low ranges there will be contact resistance.I am assuming this is a 0.1% or better unit. I have two of them, manufactured probably 60 or more years ago and the contacts have never been cleaned. They measure spot on with my 6.5 digit Ohmmeter 4-wire.

author: Vgkid
author_rank: Super Contributor
timestamp: December 01, 2021, 06:38:06 pm
content: I will second that, just give the switches a few turns, and they should clean up nicely.What model decade resistance box, and what are you using to check it?
HP 4271B LCR Question - Page 1
Forum section: electronics / general

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: October 22, 2021, 11:15:16 pm
content: Hope this is the appropriate board for this question:I recently rescued and repaired an HP 4271B digital LCR from a hamfest. Appears to work pretty well now.There is a switch on the A11 board that grounds the shield of the L pot lead. Should this switch be open or closed?I do have the service manual and am unable to find the answer to my question after a lot of reading.The only other outer conductor that is grounded is the H Pot, all outer conductors are all isolated at the chassis mountI am also looking to acquire or build a test fixture.Wally

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 23, 2021, 12:25:56 pm
content: Hmm, never noticed that switch on my unit. I suppose you could do a measurement and flick the switch to see if it has any effect. Perhaps that will give you a clue. I don't think it will break anything.For test fixtures, I bought a TH26001A which is a Chinese clone of the much more expensive HP version (see photo). Works great. About $70 on eBay.You might post your question on the Repair board rather than the Metrology board.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: October 23, 2021, 01:40:47 pm
content: The switch in question is on the A11 board under the black cover inside the unitI believe the schematic shows it closed. I suppose that I will set it there. There is very little change in readings with it closed or openI am definately considering the TH fixtures, thanks for the recommendation.
Fluke 5700 strange stains - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: October 21, 2021, 11:04:20 am
content: Hello,After opening a 5700 I have found these strange stains / traces on the main CPU board and on the digital power supply board. Why these round black inserts at the beginning (cleaning with isoprop alcool) ? Any idea ? Thank you

author: Kleinstein
author_rank: Super Contributor
timestamp: October 21, 2021, 11:27:21 am
content: It looks like something really deteriated, maybe some kind of rubber feet to test the digital board laying flat. If this is only the CPU part, it should not be so sensitive to leakage. IPA would be OK to try cleaning the residue. It may not help very much though. Just some mechanical cleaning may be enough.

author: McBryce
author_rank: Super Contributor
timestamp: October 21, 2021, 11:28:41 am
content: The holes are probably for some sort of card removal tool.McBryce.

author: TiN
author_rank: Super Contributor
timestamp: October 21, 2021, 03:12:29 pm
content: Remains of PPMs crying out loud..But seriously, those are silicon pads that due to age deteriorated. Typical for old 57** units.Just clean it off with alcohol and stick new pads.
gps-daemon-gpsd-rollover-bug - Page 1
Forum section: electronics / general

author: bingo600
author_rank: Super Contributor
timestamp: October 22, 2021, 04:06:04 pm
content: From timeutshttps://us-cert.cisa.gov/ncas/current-activity/2021/10/21/gps-daemon-gpsd-rollover-bug/Bingo

author: Halcyon
author_rank: Unknown
timestamp: October 22, 2021, 11:28:44 pm
content: Duplicate post. See:https://www.eevblog.com/forum/security/gps-daemon-gpsd-rollover-bug/
Isolator for USB port - Page 1
Forum section: electronics / general

author: IRFP
author_rank: Contributor
timestamp: October 17, 2021, 12:12:00 pm
content: Hello,Due to problems of disturbances (common ground and others) I decided to equip myself with a USB port isolator.I'm sharing with you my realization of an isolation module for data transmission via USB.I discovered a monolithic USB isolation module from MURATA that is quite efficient and easy to implement.The reference of the module is: NMUSB202MC.Below is the data sheet and pictures of the PCB.
Calibration of 34461A - Page 1
Forum section: electronics / general

author: kkayser
author_rank: Contributor
timestamp: October 01, 2021, 02:36:15 pm
content: Trouble using front panel calibration. When I push the "Perform cal step" button it says cal was successful, but the reading is unchanged. When I push the "Perform ADC cal" button I returns an error message that the reference voltage was out of range.Keysight's tech support has been absolutely no help on this problem.

author: ElizatronicWarfare
author_rank: Contributor
timestamp: October 10, 2021, 09:50:34 pm
content: Are you following the calibration procedure laid out in the service manual? Which step do you trip up at?

author: kkayser
author_rank: Contributor
timestamp: October 11, 2021, 12:34:43 pm
content: Following instructions. Pushing the left cal button says cal was done, but meter still reads wrong. Pushing the right button says cal source is out of range.

author: HighVoltage
author_rank: Super Contributor
timestamp: October 11, 2021, 12:58:21 pm
content: You have to follow the CAL instructions, otherwise it will not work.

author: ElizatronicWarfare
author_rank: Contributor
timestamp: October 11, 2021, 09:31:03 pm
content: Did you install the low-thermal shorting block as specified in the manual?

author: kkayser
author_rank: Contributor
timestamp: October 11, 2021, 09:38:26 pm
content: I am calibrating the 10 volt range so I have 10 volts connected to the input terminals.

author: bdunham7
author_rank: Super Contributor
timestamp: October 11, 2021, 09:41:15 pm
content: OK, so if you take the meter out of calibration mode and simply set it to read your 10V source, what does it say?Are you trying to calibrate a broken meter?

author: ElizatronicWarfare
author_rank: Contributor
timestamp: October 11, 2021, 11:37:56 pm
content: The ADC Cal process does not use voltages. That is the Gain Adjustment process. Did you perform the ADC and Zero Adjustment processes first? Which version of the 34460A service manual are you using?

author: kkayser
author_rank: Contributor
timestamp: October 16, 2021, 02:53:34 pm
content: I found a work around. If I apply -10 volts to the input and set the calibration voltage to -10.000000, push the cal button and the meter reads correctly at + and - 10.00000 volts. Calibration accomplished, but mystery remains.
How many Rb do you need? - Page 1
Forum section: electronics / general

author: wkb
author_rank: Super Contributor
timestamp: October 19, 2021, 02:53:01 pm
content: Fellow ham and myself acquired a new toy..

author: wkb
author_rank: Super Contributor
timestamp: October 19, 2021, 02:54:18 pm
content: well equipped

author: Johnny10
author_rank: Frequent Contributor
timestamp: October 19, 2021, 04:22:29 pm
content: Beautiful !

author: wkb
author_rank: Super Contributor
timestamp: October 19, 2021, 04:57:17 pm
content: Yes, neat. It will need to be reconfigured so that we each have one Rband a bunch of distrib amps.Things like the battery backup units, the 2.048MHz synthesisd ref output boardetc are planned for sale, same for the GPS moduleIt is too bulky for either of our ham shacks :-)Wilko

author: wkb
author_rank: Super Contributor
timestamp: October 20, 2021, 06:07:55 am
content: Sofar so good. Both MRK Rb go to lock status in a couple of minutes. And the MGPS locks to the sats too.

author: SQ9MT_PL
author_rank: Contributor
timestamp: October 30, 2021, 04:09:18 pm
content: BIG - StandardMore seriously, do you have its parameters, time stability, phase noise? etc?

author: wkb
author_rank: Super Contributor
timestamp: October 30, 2021, 04:32:56 pm
content: Quote from: SQ9MT_PL on October 30, 2021, 04:09:18 pmYes. It is a 5MHz HLN module. Specs attached.Wilko

author: wkb
author_rank: Super Contributor
timestamp: October 30, 2021, 05:35:18 pm
content: Now that we have split the unit in two it is a lot less unwieldy.Two ham shacks now have their own Rb reference

author: Johnny10
author_rank: Frequent Contributor
timestamp: October 30, 2021, 06:10:36 pm
content: So one of you got the Rubidium Unit? I didn't see the second.

author: wkb
author_rank: Super Contributor
timestamp: October 30, 2021, 06:29:11 pm
content: Original config had two Rb, one of them GPS disciplined.The 2nd unit now lives in this box, in the shack of Dave.
CAP 03458-44102 for LTZ1000ACH on reference board A9 03458-66509 - Page 1
Forum section: electronics / general

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: December 09, 2020, 08:21:46 pm
content: Hello Folks - I am looking to order the white CAP covering top and buttom of the LTZ1000ACH on reference board A9.I contacted Keysight and also their Parts ID team and they could no longer find the 03458-44102 and told me it is obsolete.However since they launched the 03458A B.E. recently (Phantom Grey Colors in official Keysight language) - they have probably redesigned the part and given it a new MPN unique for the BOM of theblackPhantom Grey edition ...Q.: Is someone aware of the new MPN ?Thank you very much for all feedbackHerzlichen Grüßen/Meilleures salutations/Best regards/Un saludoScoobyDoo

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: October 10, 2021, 04:07:39 pm
content: Hi ScoobyDoo,I realize your post is old and you may have found a solution already.Scrolled down the xDevs.com page section (https://xdevs.com/fix/hp3458a/#a9pcba) and find "Image 109: A9 Plastic caps 3D CAD model."You can download the CAD models and have a company fabricate the plastic parts. These days, it is easy to find a company that offers additive manufacturing.Hopefully, this information helps others.

author: ScoobyDoo
author_rank: Regular Contributor
timestamp: October 10, 2021, 06:22:15 pm
content: Hello leighcorrigall - thank you - however wanted to keep my 3458A in pristine condition - only original parts.For unknown reason this part 03458-44102 has status NFTS.After knocking a few times on Jim Durr's door (KS Loveland) - he shipped me two original parts as service.I heard that Keysight Loveland (Colorado) is moving its 3458A Calibration facilities to KS California - I hope it doesn not impact too much the quality of service as the Loveland facilities were especially built from bottom up to service 3458A units in USA.Best regardsScoobyDoo
Time Electronics 9814 DC calibrator - Page 1
Forum section: electronics / general

author: VintageTest
author_rank: Newbie
timestamp: March 22, 2021, 03:18:03 pm
content: Hi everyone,I can't remember if I've asked you all this or not, so here goes! I repair vintage tech and have both an old Fluke760A and a more modern Time Electronics 9814. I bought the 9814 to replace the Fluke, as it's smaller, lighter, more accurate etc, etc. However, I had tested it when I bought it at the beginning of the year and everything was hunky-dory then. I left it on the lab floor and kicked it over one day - it was standing on end. Now it seems to be an order of 1000 times too low - 10V measures as 10mV! Time are no help at all, with the 'it's obsolete' excuse, but sent me the 'Technical Manual' for the MK3 version (not the one I have), which has no schematics. There's little , if any, info on the 'net, although I did find a teardown on a 9823 - which is a different beast, but contains broadly similar cards - except the reference board. So . . . I was hoping that just mayba someone might have a schematic for this old calibrator. I've dismantled it and checked for anything which could be shock damaged or loose, but nothing. The power supplies are fairly primitive and good, the processor is working ok as well. Any help would be appreciated!Cheers all,Mel

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 22, 2021, 03:23:47 pm
content: It should be simplified version of this calibrator:https://xdevs.com/fix/te9823/Manuals in the same article.

author: VintageTest
author_rank: Newbie
timestamp: March 22, 2021, 03:44:46 pm
content: Thanks, I have that, but as I said, the reference card is quite different, although the D/A card seems similar.Cheers,Mel

author: chekhov
author_rank: Regular Contributor
timestamp: March 22, 2021, 06:52:46 pm
content: Maybe some IC decided to jump out of its socket ? (or similar mechanical issue with connections)

author: NyquistNoise
author_rank: Contributor
timestamp: October 02, 2021, 09:14:59 pm
content: Hi Mel,I've worked on quite a bit of TE gear, but never the one you're attempting to repair. I've repaired a 9823 so am familiar with the construction style. I've had a similar problem with a TE unit which was a stuck attenuator relay (out by a multiple of 10 issue). It might be worth going around and just checking any relays are switching correctly and not seized.Please do post images of the voltage standards guts - always interesting to see what makes them tick. I assume as with most Time Electronics gear the reference is a plan old diode in a potted ref box?Also if possible please do upload the technical manual, we can see if it hints at any clues to your fault!
Negative resistance displayed by 34465A when measuring DCR of an electromagnet - Page 1
Forum section: electronics / general

author: bdunham7
author_rank: Super Contributor
timestamp: September 12, 2021, 02:48:38 am
content: Since it appears to work completely properly in manual ranges, unlike the Keithley DMM6500 issue, it's just the autoranging method--although the way it stabilizes seems odd. Everyone wants fast autoranging, but there are drawbacks and you can always find corner cases.

author: Kean
author_rank: Unknown
timestamp: September 12, 2021, 03:57:59 am
content: Yes, this will be a side effect of the DUT inductance on the current source for resistance meesurement when in autoranging (and possibly other high ranges).bdunham7 is referring to a recent discussion where a similar issue was noticed on the Tek DMM6500.https://www.eevblog.com/forum/testgear/keithley-dmm6500-strange-beahavor-measuring-transformer-resistance/

author: Kleinstein
author_rank: Super Contributor
timestamp: September 12, 2021, 05:46:56 am
content: The problem is only in the auto scale mode, so a bit less critical than with the DMM6500. Still the meter should ideally regognize that there is a problem. The software should be able to detect that reading after switching the current is not stable and show a warning instead of the wrong result.With high inductance DUTs there is a known principle problem when switching ohms ranges. So this should not be such a surprize and it would make sense to consider this case in the software to detect it.

author: 2N3055
author_rank: Super Contributor
timestamp: September 12, 2021, 07:38:15 am
content: Yeah it is to be expected, and agree meter might be able to handle it better..Range switching (current switching) seems to have quite fast edge and there is counter EMF...I always wondered why manufacturers don't make autoranging parameters at least partially user settable. At least autoranging speed.This problems with autoranging seem to be more often lately, because of the race to make autoranging as fast as possible.A slight tangent if you allow me. I'm usually not a stickler for terminology but a note:Keysight shows "+Overload" in Ohms mode with open condition.It is not an overload.R&S OTOH shows "OVER RANGE" which is much better term for Ohms mode with open condition.When you're in voltage and current mode then it should "Overload", with a red background on the screen, even a beeper.In ohms mode, it is simply "Over range"

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: September 30, 2021, 02:30:23 am
content: Followup video showing a different failure mode of the same Keysight 34465A when measuring actual inductors (higher ESR than the electromagnet). Adding capacitance in parallel seems to be a workaround.

author: Circlotron
author_rank: Super Contributor
timestamp: September 30, 2021, 02:37:11 am
content: Put a scope across the electromagnet and see if the test setup is oscillating.
Voltage refences overview - Page 1
Forum section: electronics / general

author: DavidKo
author_rank: Frequent Contributor
timestamp: September 17, 2021, 07:57:33 am
content: During my search on the AD web site. I have found a overview of voltage refences (done by analog). I hope that I do not duplicate any topic, but I was not able to find a overview.Comparison of Pros and Cons of different references (from Maxim)Source:https://www.maximintegrated.com/en/design/technical-documents/app-notes/2/2879.htmlAnalog series referencesAnalog shunt referencesSource:https://www.analog.com/media/en/technical-documentation/product-selector-card/vrefb.pdfTexas InstrumentsSource:https://www.ti.com/lit/ml/snvd001a/snvd001a.pdf- there are also mentioned another references for different usageMaximSource:https://www.maximintegrated.com/en/design/technical-documents/tutorials/7/719.html
Need a manual for a hp2509a digital  clock  - Page 1
Forum section: electronics / general

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: September 08, 2021, 05:51:48 pm
content: Hi,I'm troubleshooting an hp2509a digital clock but can't find a ops and service manual.Any ideas where I could find one?Cheers,Corby

author: edpalmer42
author_rank: Super Contributor
timestamp: September 08, 2021, 07:49:22 pm
content: I see that it was originally the DY-2509A from Dymec. Did you look under that part number? I did a brief search but didn't find anything interesting.Ed

author: doktor pyta
author_rank: Frequent Contributor
timestamp: September 08, 2021, 08:52:25 pm
content: maybe here:https://www.abebooks.com/servlet/BookDetailsPL?bi=30555911754&searchurl=an%3Ddymec%26sortby%3D17&cm_sp=snippet-_-srp1-_-title3
How do I switch off the VFD on Keithley 2000/2010 DMM? - Page 1
Forum section: electronics / general

author: enut11
author_rank: Super Contributor
timestamp: September 05, 2021, 02:25:26 am
content: My newly acquired old Keithley 2010 DMM will be spending long periods of time monitoring or logging data.The 7 segment VFD characters are already showing signs of dimming, in particular the central '--' bars that change '0' into an '8'.I would like to switch off the VFD for most of the monitoring/logging process and only switch it on when needed. This may be possible under program control but I cannot see how to do this in stand-alone mode.A crude method may be to interrupt the VFD power line but this will probable cause other problems?I believe the K2000 and K2010 use the same display module.Any suggestions on how to proceed?

author: enut11
author_rank: Super Contributor
timestamp: September 05, 2021, 02:29:16 am
content: K2010 circuits.See file #11 for display schematic.

author: picburner
author_rank: Frequent Contributor
timestamp: September 05, 2021, 02:59:58 am
content: In my k2010 I interrupted the connection to the vfd display filament and interposed a switch located on the rear panel.P.S. the A15 firmware is also on the network, updating from version A10 does not require re-calibration.

author: enut11
author_rank: Super Contributor
timestamp: September 05, 2021, 03:40:31 am
content: Thanks @picburner. Sounds like the switched VFD supply solution does work without problems.I see the Vf1 and Vf2 lines to the DS401 (DD-52) display pins 1 and 34 . So a DPDT switch here should do the trick?What improvement does the A15 firmware offer over A10?

author: Anders Petersson
author_rank: Regular Contributor
timestamp: September 05, 2021, 06:53:46 pm
content: With K2010 I use SCPI command:DISP:ENAB OFF. Surely that's enough to save the VFD?You asked about standalone mode but I fail to see how you do long logging sessions without a computer connection.

author: Gyro
author_rank: Super Contributor
timestamp: September 05, 2021, 07:02:43 pm
content: It's possible that running the filaments without anode (segment) current could cause poisoning of their emissive surface. It depends how the SCPI command switches it. Filaments cold might provide longer life.I don't know though, and it would take a long time to determine either way.

author: enut11
author_rank: Super Contributor
timestamp: September 05, 2021, 09:30:22 pm
content: Thanks for everyone's input. I knew nothing about how VFDs work. Came across this video by Dave.It explains typical VFD working voltages. The filament (or cathode) that @picburner mentioned is very low voltage so easily switched.

author: enut11
author_rank: Super Contributor
timestamp: September 05, 2021, 09:32:40 pm
content: Quote from: Anders Petersson on September 05, 2021, 06:53:46 pmThanks Anders. Some of the use will simply be monitoring without data logging.enut11
Keithley for temperature reference.  - Page 1
Forum section: electronics / general

author: chrismholt
author_rank: Newbie
timestamp: August 29, 2021, 11:35:35 pm
content: I have a keithley 2002 that has a nice option for measuring an rtd that allows me to enter callibration coefficients for a platinum rtd. I was wondering if this is a reasonable tool for making a secondary standard temperature reference or if I should spend the extra money to buy a purpose built rtd reader from hart scientific.

author: TiN
author_rank: Super Contributor
timestamp: August 29, 2021, 11:46:36 pm
content: K2002 is just a readout for the probe, so key point is to have your PRT calibrated with actual measured coefficients. Otherwise you don't know how accurate your temperature measurements are.

author: mzzj
author_rank: Super Contributor
timestamp: August 30, 2021, 06:17:20 am
content: Quote from: chrismholt on August 29, 2021, 11:35:35 pmAs usual: "it depends"On a quick glance 2002 offers about 20ppm accuracy on ohms range. This would be 2 milliohms for 100 ohm (S)PRT and abouts 0,006 K accuracy on temperature.For many purposes this might be good enough and for some uses its pretty much useless.Good reference resistor and RTD readout offers 20 times better accuracy but you are easily looking at 30-40k usd investment.

author: chrismholt
author_rank: Newbie
timestamp: August 30, 2021, 09:27:02 am
content: Thank you for the input. I like your simple accuracy calculation.
Muirhead 10 X 0.1uF B-23-CP new to me, help with information please - Page 1
Forum section: electronics / general

author: sarel.wagner
author_rank: Regular Contributor
timestamp: August 22, 2021, 04:55:48 pm
content: I got gifted this unit yesterday. I am unable to find any info or documentation

author: Gyro
author_rank: Super Contributor
timestamp: August 22, 2021, 06:50:56 pm
content: Muirhead were a UK manufacturer of precision test equipment, mainly resistance and capacitance decade boxes, but also Weston Standard cells, servo motors and synchro transmitters, resolvers etc for aircraft use. They also made some electronic things like precision signal generators. They were founded way back in 1894 and bought by Vactric Controls in 1972 (the trail goes a bit cold from there).What you have there is a nice single decade capacitance box, running from 100nF to 1uF. As you can see from the switch contacts at the bottom, it switches in individual capacitors in combination to achieve the 100nF steps. It probably uses switched combinations of 1 x 100nF, 2 x 200nF and a 1 x 500nF to make up the individual steps. It almost certainly uses Mica capacitors for low dissipation factor, low temperature coefficient, and long term stability. The larger value capacitors could well be made up of paralleled 100nF capacitors too, for best matching and stability.It probably dates from the 1950s +/- 20 years and is probably still quite accurate and useable. Be very careful if trying to take it apart, you might find that the capacitor box is wax filled (I've never seen one open). Unfortunately there doesn't seem to be any indication of voltage rating, but I would think at least 100V, so suitable as a capacitance substitution box for most electronic projects.If you do a forum search for 'Muirhead', you will find quite a few hits for their stuff, mainly resistance boxes, voltage dividers and standard cells, which show their quality of construction. Forum member lowimpedance (I think) has a bunch of old Muirhead catalogues hidden away at the back of a filing cabinet andmightbe able to help you out if you are patient.A nice gift.Edit: Hey, my 7000th post, I'm glad it's on a nice subject!

author: sarel.wagner
author_rank: Regular Contributor
timestamp: August 22, 2021, 07:00:49 pm
content: Thank you Gyro. Glad it was #7kBeen all over, including doing just that on here, but very little info on their capacitors, hence the ask. Will see if I can track down the member here with maybe a catalog or manual. Interested in them specs.... I do have both a DER EE tester and an old Heatkit to test with, will stick to sub 60V to test.
Agilent 64465A display dead - Page 1
Forum section: electronics / general

author: jonpaul
author_rank: Super Contributor
timestamp: August 16, 2021, 01:07:18 pm
content: Bonjour, just got an Agilent 64465A meter used, supposedly in warranty and in excellent condWonderful upgrade from y ancient Fluke 8842A.After a few turn-ons, now the screen is dark, even though the relays click normally during startup and CAL.Anyone have this series of meter 34461A, 34460A, 34465A, 34470A etc?Ever see any bad/intermittent displays?Any experience with Agilent service?MANY THANKSJon

author: nctnico
author_rank: Super Contributor
timestamp: August 16, 2021, 05:22:32 pm
content: Quote from: jonpaul on August 16, 2021, 01:07:18 pmYes. I had to return a brand new 34461AQuoteUsually quite good. Just contact them and see how it goes.