hybridfree/eevblog-posts huggingface dataset:
RT + ACV standard - upscale to HV? - Page 1
Forum section: electronics / general

author: Rax
author_rank: Super Contributor
timestamp: May 22, 2023, 03:59:48 am
content: Having a good RT (Gertsch PT-5) and a reasonably good 10VAC voltage source (Fluke 510A), I wonder how well and to what point (accuracy, non-destructive upscaling, etc.) I should be able to precisely multiply the 10V to a higher value.Obviously, fractional output of the 10V is trivial, but what about scaling the 10V up?Looking into literature currently but welcome thoughts and recommendations. Thank you!

author: TizianoHV
author_rank: Regular Contributor
timestamp: May 22, 2023, 12:20:18 pm
content: What is the output frequency of the 510A?The PT-5 can work at voltages up to 0.35*f. To steep up the voltage you could use any transformer with low magnetization current (higher voltage rating is better 480V - 48V, "small") and use the PT-5 to find the ratio of the step-up transformer by doing a null measurement.After establishing the ratio of the step-up transformer you can easily calculate the output voltage. The issue with cascading two transformers is an increase of the output impedance, this means that applying a load will create an error.I did the same thing with a smaller RT + 20VA transformer and the voltmeter burden was enough to cause a voltage drop.What are you going to use it for? Do you need only a stable source or do you need accuracy as well? Do you have a good multimeter to check voltages?

author: alm
author_rank: Super Contributor
timestamp: May 23, 2023, 06:58:58 am
content: The RMS voltage is limited to 0.35*f or 350V, whichever is less.Theinstruction manualsays that the ratio transformer can be used in reverse, but that accuracy will be worse, and will rapidly become worse as the ratio becomes higher. So accuracy at x10 will probably suck. A bridge circuit with a stable source that you compare to the 510A using the ratio transformer and a null meter would probably perform better, but note the difficulty of using an AC null meter discussed in earlier threads of yours.
Upgrade a garbage device - Page 1
Forum section: electronics / general

author: ssmsc
author_rank: Newbie
timestamp: May 08, 2023, 02:21:43 pm
content: As is well known, Tonghui's TH2690 isplagiarism of keysight B2983，and didn't learn the essence.https://www.eevblog.com/forum/metrology/plagiarize-keysight-b2983/msg4348219/#msg4348219Coincidentally, my friend has a Tonghui device with a noise of 10fA without clearing the zero.I have decided to make some simple changes to reduce current noise as low as 1fA.However, even if the noise can be improved, Tonghui has done too poorly in many details, such as the large temperature and voltage coefficients of the feedback resistor.The cable selection at the input end is incorrect….

author: zrq
author_rank: Frequent Contributor
timestamp: May 09, 2023, 12:46:51 pm
content: I would be curious about what actually caused the higher current noise and what did you modify.

author: dhyddr
author_rank: Newbie
timestamp: May 10, 2023, 01:07:13 am
content: Nice work
Pendulum (or) RAPCO (or) Spectracom 2804 GPS master Clock - attempting repair... - Page 1
Forum section: electronics / general

author: Uky
author_rank: Regular Contributor
timestamp: May 29, 2023, 08:59:45 am
content: Greetings.Picked up a faulty ... 2804 GPS Master Clock at a locan flea market.Fault indicated: "Locks anywhere near 10 MHz +/- 5Hz" And yes, when turning on and after acquiring some sattelites, it ends up -5Hz.The OCXO is a RAKON CFPO-D03 51B S12. By the look of it, I think that the footprints is also used by several other brands.Searching the internet for any of the brands + 2804 returns no information other than notice of "obsolesence".It was manufactured in 2008.Anyone having access to a manual with schematics?Best RegardsUlf KylenfallSM6GXV
Leader 856 multimer - any info? - Page 1
Forum section: electronics / general

author: widlokm
author_rank: Contributor
timestamp: July 06, 2021, 10:31:35 am
content: Hello,I've bought a Leader 856 multi-meter as a companion to trusted HP3468B. The meter is working, has a nice display, but the only info I found about it is the attached pdf.Is there any manual or better a service manual available for it? I found a few pages offering it if You register (like ameblo.jp), but for me it seems to be a scam - please correct me if I'm wrong.Anyway if someone is interested I can post a few images, from disassembly / cleaning / restoration.Thanks in advance,Michael Widlok

author: widlokm
author_rank: Contributor
timestamp: July 07, 2021, 08:37:52 am
content: The meter turns out to be OK (still must check the accuracy) and build quality is nice.Case was really bad initially, however it does not have any vents, so inside is almost perfect. The only obvious problem is dead and leaking 2.4V NiCd battery. PCB routing is nice, and there were metal screens over analog sections. Now I'm thinking of replacing battery with supercap, it seems that it is only to keep setting when turned off. It seems that meter use 80C51 MCU with 27C128 memory + two 82C55 IO chips. Main ADC is an add-on module soldered on main pcb. The good thing is display - big, bright and very readable, much better then on HP3468.

author: tongbajiel
author_rank: Newbie
timestamp: October 21, 2022, 03:59:28 pm
content: Do you have main OKI mcu firmware backup please... my meter has broken mcu chip

author: widlokm
author_rank: Contributor
timestamp: October 24, 2022, 07:39:46 am
content: I can only read DIP external memory unfortunately, not the 80C154 chip. According to datasheet it is ROM/OTP so reading might not be possible anyway. I'm not familiar with these MCUs so I might be wrong here.Are You 100% sure that You have broken MCU?

author: Jordanch68
author_rank: Newbie
timestamp: May 01, 2023, 04:35:00 am
content: Hifiengine has the user and service manual if anyone needs it.
BG7TBL GPSDO rubidium frequency standards - Page 1
Forum section: electronics / general

author: Raindog
author_rank: Contributor
timestamp: May 04, 2023, 12:24:23 am
content: Hello all,Was wondering if anyone out here has tried one of the rubidium GPSDO standards by BG7TBL. I have one of the GPSDO OCXO standards and have been really happy with it. I have been thinking of obtaining one of these because you know, why not.Best Regards,Craig Petersen - N7UQA

author: bdunham7
author_rank: Super Contributor
timestamp: May 04, 2023, 01:16:47 am
content: Unless you need to use it without a GPS signal, I think the performance will actually be a bit worse vs a GPS disciplined OCXO.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: May 04, 2023, 02:03:15 am
content: a difference - rubidium more stable in short term. gps ocxo - under influence of voltage correction. I'm watching how phase of gpsdo shifting back and forward comparing to regular ocxo , so it constantly adjusting frequency.so for a maximum resolution standalone ocxo or rubidium as reference more preferred. for a regular 8D counter, a well-constructed standalone ocxo , that constantly on state - more then adequate.

author: MIS42N
author_rank: Frequent Contributor
timestamp: May 05, 2023, 01:41:03 pm
content: A rubidium standard needs to be calibrated. For example one advert says '20 year aging less than 0.005 ppm' (or 5 pp billion). I have been building cheap GPSDOs and with good GPS reception and a well burned in OCXO (i.e. running for 2 weeks) it routinely delivers 10MHz to 0.1ppb (the possible drift of a Rubidium in a year).You can get the best of both worlds by having a cheap GPSDO and using it to calibrate the Rubidium. GPSDOs are usually phase locked to the GPS signal. Typically, divide the 10MHz GPSDO signal to get 1MHz, do the same with the Rubidium, compare the phases over several hours. The GPSDO phase can move back and forth by many nanoseconds (can be over 100 with poor GPS reception) so comparing at 10MHz can be a problem. For instance, if the GPSDO phase is 100ns out at the start of a 3 hour comparison, and 100ns out in the opposite direction at the end of 3 hours, the comparison error is 2 parts in 10^12.

author: thinkfat
author_rank: Unknown
timestamp: May 08, 2023, 07:04:30 am
content: Unless you need the inherent stability of a Rb for times when you have no GPS reception, I'd say, not worth it.
Spectracom 8189 GPS NetClock - looking for manuals - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: April 27, 2023, 12:37:47 pm
content: I just acquired a Spectracom 8189 GPS NetClock Ethernet Time Server. I got it working looking at view only documentation site but I'd like to have a PDF copy of it. The site I found, I don't feel safe enough to actually download. It's one of those with an online document viewer. It has all the hallmarks of scam site.Does anyone know of a SAFE place to download manual for Spectracom 8189 GPS Netclock?

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: April 28, 2023, 03:24:05 pm
content: You might try calling them up or emailing. Maybe they'll send you one.https://www.allbiz.com/business/orolia_1h-585-321-5800

author: tkamiya
author_rank: Super Contributor
timestamp: April 28, 2023, 07:48:35 pm
content: Great. Thank you for that suggestion.According to a gentleman at tech support, this device is so old it's not even mentioned on company webpage. But he had a personal copy of PDF that he is going to email it to me.I actually found this on some website (other than the official one). But its one of those with view only and with fake "download" link. I didn't trust them what it would actually "download." So trusted source like this was wonderful.2 minutes later, the official manual has arrived in my in box.
Advantest TR8641 Electronic Picoammeter Manuals? - Page 1
Forum section: electronics / general

author: lugaw
author_rank: Regular Contributor
timestamp: June 12, 2022, 03:18:38 am
content: Please help me find manual for this picoammeter.

author: lugaw
author_rank: Regular Contributor
timestamp: June 12, 2022, 06:00:32 pm
content: It seems to be a cousin of Keithley 414S picoammeter.I need to figure out what the Fine and Current Compensator knobs do to the system.

author: serg-el
author_rank: Regular Contributor
timestamp: April 26, 2023, 05:13:52 pm
content: User manual TR6841

author: Swainster
author_rank: Frequent Contributor
timestamp: April 27, 2023, 10:34:41 am
content: The 'S' bit in the 414S refers to suppression, in particular, the ability to suppress or null out a large fraction (typically 2 decades worth) of the input current in order to look at tiny variations. For instance, you might want to show a 10uA F.S. variation on top of a constant 1mA bias current. It is basically like have a stable constant current source in series with the picoammeter.
Looking for Rapco (Pendulum) 2804B GPS Clock w/OCXO "CLIP" - Page 1
Forum section: electronics / general

author: Uky
author_rank: Regular Contributor
timestamp: June 15, 2023, 11:34:38 am
content: Greetings.Having picked up a RAPCO (Pendulum) 2804B GPS-clock at a flea market, I posted a message searching for a manualon the time-nuts mailing list. A user manual was kindly provided and it did help in starting the troubleshootingprocedure.I am however stuck in trying to figure out why the frequency locking of the built-in OCXO does not work.The control loop circuitry adresses an AD7846 - 16Bit Voltage Output DAC that controls the OCXO.After indicating "Frequency Lock", the DAC output voltage goes from a value that sets the OCXOclose to 10 MHz, but then latches up and saturates at "99.9%" of the tuning range. This putsthe OCXO at 10.000.002 MHz...I am presently investigating if the problem is the 7846 (Datasheet available) but if thisIC is good I don't think I can go any further.Rapco was purchased by Orolia and then by Safran. The 2804 is obsolete since a long timeago. I dont think approaching Safran would be successful. If anyone has more informationthat the user manual, I would be grateful.

author: Uky
author_rank: Regular Contributor
timestamp: June 15, 2023, 12:37:29 pm
content: ... I think the request for a service manual can be withdrawn.There are two pieces of ALTERA CPLD's where at least one of them outputs data to the DAC.Regardless of having the DAC socket populated or not, testing the DB0...15. The lower bits are "alive" but the upper dead.Either stuck logic high or low or somewhere in between.Will salvage some parts. The rest -> scrap.
FLUKE 931B RMS Differential Voltmeter - operation and other checks? - Page 1
Forum section: electronics / general

author: Rax
author_rank: Super Contributor
timestamp: April 21, 2023, 03:11:20 pm
content: Hi all,I recently grabbed a functional 931B (including even a fully working battery option), and am going through assessing its condition.I'd appreciate if anyone else having this can confirm the 2-13(i) step in the Operational Test sequence should return slight fluctuations of the needle (as opposed to solid "zero" indication). I assume this is OK - I get excursions of the needle of about .5 scale units around zero - but could use a confirmation.Thanks!
ASL F25 circuits - Page 1
Forum section: electronics / general

author: Sengcid
author_rank: Regular Contributor
timestamp: April 19, 2023, 06:47:08 pm
content: The F25 and F250 (a later version) are 10ppm resistance bridges for thermometry. Operating at 375Hz they are less tolerant of long cables (no quadrature balance). The higher frequency also permitted a smaller ratio transformer.Edit: Oops, sorry for the first item. It was the contents of the collection of monographs referred to in the footnotes. They can be accessed via the link: -https://drive.google.com/folderview?id=1TbomXeoBbIe-IVADaOOmyyLH9le-3wAt
ASL F26 and F300 circuits - Page 1
Forum section: electronics / general

author: Sengcid
author_rank: Regular Contributor
timestamp: April 16, 2023, 06:43:15 pm
content: The F26 and F300 (a later version) are 10ppm resistance bridges for thermometry. There are hundreds around the world worthy of rescue from landfill.See, also, separate threads for the F17 and F18.

author: Sengcid
author_rank: Regular Contributor
timestamp: April 16, 2023, 06:45:37 pm
content: The ratio transformer module is definitely worth saving. Herewith a pic with thanks to another eevblogger.
10 MHz 0.1 ppb OXCOs on ebay for $3-20 - Page 1
Forum section: electronics / general

author: rhb
author_rank: Super Contributor
timestamp: April 12, 2023, 09:20:21 pm
content: FWIW there are a bunch of bare modules and eval board clone versions of the CTI OSC5A2B0 for crazy cheap.Best ebay search string is "OCXO 10MHz Frequency Module Crystal Oscillator Constant Temperature" for the $20 plug and play versions and "OSC5A2B0" for the $3 bare modules. I bought 5 of the former and 10 of the latter.The two eval board versions that I've tested hold 0.1 ppb with some scrap bath towel to mitigate drafts. Limit of my GPSDO is around 0.001 ppb best case. So we are talking very accurate frequency references for $20 delivered.They arrived set within 1-2 ppm, but a bit of tweaking using a GPSDO and scope got them to 0.1 ppb. I'm going to mount one in a case withnone, just insulation and another in a case with active temperature control and then monitor all 3 long term.

author: JohnPi
author_rank: Regular Contributor
timestamp: April 15, 2023, 07:51:19 pm
content: Any measurements on jitter or Allan variance ? A board like this with a simple DCDC and little filtering or isolation is unlikely to have good short-term characteristics.

author: MIS42N
author_rank: Frequent Contributor
timestamp: April 16, 2023, 12:21:53 pm
content: Are you talking parts per billion or parts per million. I have played with OSC5A2B02 for a few years now, they will reliably settle after 15 minutes warmup to 10MHz within 0.1Hz which is 10 ppb. To get them to settle better than that they have to be powered for days (if used every few days then 2 days is OK. If not used for months can take a week). Also, their sensitivity to the control voltage is about 1ppm/V so to get 1ppb requires the control voltage stable to 1mV or in your instance 0.1ppb requires stable to 100uV, which needs a pretty good voltage regulator (not a run of the mill 7805).I use them in a cheap GPSDO design, the best I have had reliably is stable to 0.04ppb while being disciplined.https://www.eevblog.com/forum/projects/budget-gpsdo-a-work-in-progress/msg4804529/#msg4804529Regardless of ppm/ppb etc. they may not be the best OCXO around but certainly great value for money.
Help Me Understand My Resistance Measurement Error? - Page 1
Forum section: electronics / general

author: clansd99
author_rank: Contributor
timestamp: April 11, 2023, 11:44:49 am
content: Hi all,I've got a WEIRD issue testing the resistance of various 1/4W resistors with my multimeters.I initially thought my BM235 meter was busted, since any resistors over around ~10kOhms measured by hand with my probes across the leads were way off from their stated values (which were verified with my component tester). For my birthday I ordered the 121GW and figured the matter must be solved so paid no more attention - until recently.When measuring resistors 10k and up with the 121GW the other day, I realized they were quite off! Generally LOWER in value than I would expect, by a significant amount. I figured there wasno waythe same issue would crop up with a second meter and it must be an error in my test setup.In the end, I found that if I connected the resistors up to the meter via a pair of test clips, the problem vanished. But, measuring any resistors over around ~10kOhms by hand with a standard probe pressed onto the leads causes the issue mentioned above.I don't remember having this problem in the past - what's going on here? In particular, why are the measured resistances LOWER than their real values?Thought this might be an interesting topic for discussion and that (hopefully) a lot of people could learn from this.

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: April 11, 2023, 11:56:14 am
content: your hand resistance is coming in parallel with the resistance being measured and that reduces the overall resistance.Ensure that you are not touching both the leads of the multimeter when measuring the resistance.

author: clansd99
author_rank: Contributor
timestamp: April 11, 2023, 11:57:33 am
content: Quote from: EEEnthusiast on April 11, 2023, 11:56:14 amYes you must be right! I just measured the resistance just pressing the leads against my fingers to be ~0.6MOhm, which when put in series with the resistors in question gave exactly the numbers I was seeing. Thank you!
Semiconductor leakage measurement in HTRB - Page 1
Forum section: electronics / general

author: arijav
author_rank: Contributor
timestamp: April 09, 2023, 09:43:33 pm
content: Hello,I am trying to design a test system for HTRB of power semiconductors. The system will have a High Voltage Power Supply (f.i. 2kV) which will be connected in series to several Power Semiconductors (Devices Under Test) in parallel whose leakage needs to be measured. Each one of the Power Semiconductors will have a protection switch in series (3.3kV SiC MOSFET) and a measurement circuit (logarithmic amplifier measuring the range of 1nA to 10mA). I need a protection circuit to assure that in case of breakdown of the Devices Under Test, the measurement circuitry (AD8304 + ADC, etc...) does not see the 2kV or >10mA. A series current limiting resistor at the output of the HVPS will not do the job as the DUTs need to see the 2kV @10mA in worst case. I am not sure if I can solely rely on the protection switches as I think I will need at least 10us to switch them open.Do you have any idea on how to limit the current in case of failure to 10mA and assure the AD8304 does not see the 2kV?Thanks,Javier

author: Kleinstein
author_rank: Super Contributor
timestamp: April 10, 2023, 07:31:17 am
content: It is usually quite easy to protect a current measurement part, so that it can withstant quite a bit more current. With clamping diodes the current measurement part should be ok with some 1 A and maybe also 10 A for a short pulse. The question for the current limiting is more on how to protect the power supply and DUT, so that they don't blow up.This would normally be something as part of the power supply, so that the supply could compensate for the voltage drop on some series resistance.

author: PartialDischarge
author_rank: Super Contributor
timestamp: April 10, 2023, 07:52:10 am
content: IMO you should reevaluate the 10mA target, seems too high, do you really expect the leackage to get into the 1..10mA range?Other than that your requirements call for a floating (battery powered) protection circuit that measures the current and switches the PSU off via fiber optic signal for example.

author: MK
author_rank: Regular Contributor
timestamp: April 10, 2023, 09:07:00 am
content: Another way to measure is to set a current through the device, and measure the voltage, that way you do not exceed the limits usually

author: mzzj
author_rank: Super Contributor
timestamp: April 10, 2023, 10:56:40 am
content: Quote from: PartialDischarge on April 10, 2023, 07:52:10 am10mA sounds reasonable for large 1200v IGBT in HTRB (High Temperature Reverse Bias) test.
Unknown Voltage Reference - Page 1
Forum section: electronics / general

author: Survest
author_rank: Newbie
timestamp: April 08, 2023, 03:27:03 pm
content: I recently was parting a broken fluke 881A diff voltmeter. I parted out all the nice wire wounds and what I suspect to be the voltage reference. I have no clue what it is, it is a small 3 pin metal can, branded LT, with a part number SU443 516. Can anyone ID this or provide any ideas on how to test? I don't want to blow it up. Picture below.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 08, 2023, 04:02:40 pm
content: According to the manual for the Fluk 881A the SU443 is a p channel JFET. So an old part with no special value except if someone need an 1:1 replacement.Hard to tell the data. In many cases the gate is connected to the case. If not, one could find out the pinput by testing 1 pin relative to the other 2 connected in diode mode. The gate pin should be the kathode to a diode to the other 2 pins. Drain and source are usually interchangible anyway. One could check the FET as a source follower ciruit, e.g. some 10 K in series to the gate as protection to a function genrator, drain to the negative supply and source with some 10-100 K or so to a +9 V supply.Even if not very useful as a differential voltmeter the KV divider part and maybe the reference part could still be a useful part as a adjustable votlage source.

author: mzzj
author_rank: Super Contributor
timestamp: April 08, 2023, 04:17:47 pm
content: Kleinstein: I see only two terminals?Assuming this is a voltage reference you can test it out with around 10 volt supply and 10kphm resistor in series.881A could be too old for badgap references to exist, in that case we have probably around 7 volt zener?

author: Survest
author_rank: Newbie
timestamp: April 08, 2023, 04:24:45 pm
content: I see. I assumed it was the voltage reference because it was a weird looking LT can. Any idea on what the internal part number for the Vref is? I pulled out all the other metal cans, and they all appear to be jfets or bjts.

author: Survest
author_rank: Newbie
timestamp: April 08, 2023, 04:26:08 pm
content: Also please post the 881a manual, I cant seem to find it.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 08, 2023, 04:36:25 pm
content: I have found a manual for a related mode 871. The reference is supposed to be 2 x 1N3497, which are zener diodes in a small glass case, just like a 1N4148.

author: Survest
author_rank: Newbie
timestamp: April 08, 2023, 04:50:04 pm
content: Thank you very much. I guess the reference is nothing special.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 08, 2023, 06:39:30 pm
content: The 1N3497 diode are somewhat similar (smaller temperature range) to the more common 1N825. So nothing special old style. If they are well aged they can still be relatively stable and possibly low noise.I don't think the JFET would be something special - it is rare now to use P channel jfets for low noise. They may have relatively low 1/f noise for there time.
would like to get my "imperfect" Agilent 34410a calibrated : advice? - Page 1
Forum section: electronics / general

author: vsmith
author_rank: Regular Contributor
timestamp: April 07, 2023, 07:20:21 pm
content: Hi all.I have an Agilent 34410a multimeter that I really like, especially because it has very low warm up drift (I mean, on the order of <3ppm over the first hour). I would like to use this meter as my in-house "standard" but know that I cannot send it in to Keysight because it sometimes fails at start up (the error is FPGA Comms Fail). This only happens every so often and when it does, it will boot up properly if simply turned off and back on again)Keysight, of course, will want to repair/replace which I cannot afford, and if they just return it, I will be charged a hefty "evaluation fee".The meter has no other errors, no other symptoms, and the start up error is just that, an initial fault which does not affect the measurement accuracy or stability of the meter.What I would love to find is a Cal Lab (even a well maintained Hobbyist Cal Lab) who will work past the error if it happens to come up at turn on, and perform full calibration, preferably with adjustments for all cal points.I am not trying to "cheap out" here (unless you count trying to avoid replacing my meter!), am happy to pay for calibration.I would appreciate any recommendations (for specific cal labs!) or if any of my fellow Metrology "nuts" are equipped and willing, volunteers to perform this service for me. Have any readers had good experience with a Cal Lab willing to handle "special projects" like this?Victor
ESA609 Safety analyzer - Page 1
Forum section: electronics / general

author: jsolomonsc@gmail.com
author_rank: Contributor
timestamp: April 06, 2023, 07:42:33 pm
content: I have two on the bench now. going though what little info I have, the mfg performed a "ground wire leakage current verifications". How is this test performed to verify the accuracy of the 609. Wiring hookup would be great if you can.thank you in advanced.
3458A problems with AC voltage measurement and with the ACAL AC procedure - Page 1
Forum section: electronics / general

author: Denisok09
author_rank: Newbie
timestamp: May 02, 2020, 11:34:20 am
content: Good afternoon!I have a Keysight 3458A and it has problems with AC voltage measurement and with the ACAL AC procedure.When powering up the 3458A, the error "110, "CALIBRATION REQUIRED – ACAL" " occurs.When I run the ACAL 2 procedure " ACV flatness, gain, and offset” messages are displayed on the 3458A screen:ACAL ACV RATIO 1;ACAL ACV RATIO 2;ACAL ACV RATIO 3;ACAL ACV RATIO 4.When the ACAL procedure is completed, the "ERR" symbol is displayed on the 3458A screen. There are three errors:209, “Hardware failure-internal overload: 228”;210, “HARDWARE FAILURE- CALIBRATION REQUIRED”;101, “Calibration ERROR“.The 3458A calibration manual on page 100 specifies const_id “228”, Description “ab ratio”, Constant derived from”ACAL AC".CAL? 288,0 0CAL? 288,1 -7,129796677E+04Please help me understand the issue.P.S. I apologize for English – I use an automatic translator.

author: Dr. Frank
author_rank: Super Contributor
timestamp: May 02, 2020, 04:18:27 pm
content: I did not find any hint in the schematics, what ab ratio, related to CAL? 228, could mean.MOn my 3458A, CAL? 228 equals about 370.345E3, or so.Maybe there's an error in the ACV path, therefore please apply several AC volatges, use the different modes, and check if you find any fail measurements. Then we can proceed from then onFrank

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: May 02, 2020, 05:53:28 pm
content: I had a similar issue several years ago. I can't remember know how I determined which range was being adjusted, but I narrowed it down to C104 which is a 400pF capacitor. In-circuit it measured 200pF and I removed it. I measured it again and got the same results. I replaced it with one from a donor A2 pcb and it started working after that.I recommend probing the capacitors first as that would explain the overload error. C104 is an odd value and looks like a SMD part with legs soldered to it.Good luck

author: syau
author_rank: Frequent Contributor
timestamp: April 20, 2023, 10:14:36 am
content: Sorry for digging out this old thread.I got a 3458A with exactly the same issue, replaced the EL2039 from Utsource fixed it.
ASL F18 Circuits - Page 1
Forum section: electronics / general

author: Sengcid
author_rank: Regular Contributor
timestamp: March 21, 2023, 07:36:02 pm
content: The F18 is a 0.1ppm resistance bridge (for thermometry: low operating current and noise matched from 0.3 to 300 Ohm).Feedback welcome.Edit: -The latest version can be found via the link: -https://drive.google.com/file/d/1zstp1oqveGga9d17Cta1mru3DqHdr0xW/view?usp=drivesdk

author: Sengcid
author_rank: Regular Contributor
timestamp: March 28, 2023, 06:41:46 pm
content: I hit a problem with the modify option: not able to remove attachments. Herewith latest intro and contents. Herewith also a link to the collection of documents referred to in the footnotes: -https://drive.google.com/folderview?id=1TbomXeoBbIe-IVADaOOmyyLH9le-3wAt
Gertsch Ratio Transformer - maintenance - Page 1
Forum section: electronics / general

author: Rax
author_rank: Super Contributor
timestamp: March 25, 2023, 09:29:59 pm
content: I just acquired a Gertsch PT-5 in good cosmetic shape. It seems very precise - just about on par with my RV722 DC divider (within the bounds of the expected accuracy of AC vs. DC of my meters, but frankly it is a bit surprising how exact it is).The switches, though, are a bit fussy. This must have sat for decades. What have others done with this in terms of maintenance? Just work the switches to get them mechanically clean, or open it up and condition with some Deoxit? Unsure what would be advisable, though can't imagine the second option harming anything.Thanks!

author: Vgkid
author_rank: Super Contributor
timestamp: March 25, 2023, 10:24:09 pm
content: Have you read this yet:http://www.ciphersbyritter.com/RADELECT/RATIOTRN/RATIOINS.HTM

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 26, 2023, 03:45:52 am
content: I'd use a small amount of Deoxit, using a toothpick or something, rather than spraying it everywhere. That should do it. FWIW, most of those ratio transformers are more accurate than similar resistive dividers. General Radio was able to specify them within 200 ppb!

author: Rax
author_rank: Super Contributor
timestamp: March 26, 2023, 10:34:07 pm
content: I used a cotton swab moist with Deoxit (but excess wicked away), and then I placed the rotor contact "leaf" in between positions (so I'd have access to it) and wiped it. Mind you, the top and bottom deck don't have the rotor contact in the corresponding place - so I had to switch to different positions top vs. bottom to gain access to the rotor contacting leaf.It seems all good now to me.Thanks both!

author: guenthert
author_rank: Frequent Contributor
timestamp: March 27, 2023, 06:42:17 pm
content: Google finds:http://manuals.repeater-builder.com/te-files/MISCELLANEOUS/GERTSCH%20RadioTran%20Instruction.pdfIf I understand the nomenclature correctly Gertsch PT-5 is the Gertsch Products RatioTran model 5, listed in their catalog as RT-5. Or perhaps the renaming of the models happened when Gertsch became part of Singer?

author: Rax
author_rank: Super Contributor
timestamp: March 28, 2023, 04:22:20 am
content: Quote from: guenthert on March 27, 2023, 06:42:17 pmMy questions exactly. As far as I can tell, the PT-5 and the RT-5 are the same unit. My specific one is apparently a "PT-5R," as I really wanted a rack unit. The vertical ones seem impossible to me from a practical standpoint.Also, extremely precise as far as I can tell. I was able to dial different digits one by one; only the last leaves me a bit unsure, and the potentiometer has such fine effect it's difficult to convince my meter to react very convincingly, but I was able to fine tune the last count with fine and patient tweaks of the pot.Very satisfying - an incredibly infinitesimally small but distinct and precise effect from RT just as I was able to see with the KVD. Wow.
Best practice for Keithley 2001 voltnut style measurement? - Page 1
Forum section: electronics / general

author: aronake
author_rank: Frequent Contributor
timestamp: March 24, 2023, 03:57:09 pm
content: Hi!I have a very stable and well aged Fluke 8845a, an even more aged and stable 34401a and a pretty new DMM6500.I found a pretty good deal on a Keithely 2001 and though i should upgrade my volynuttery with one more digit. I was well aware that Keithley 2001 is considered noisy, but though I could remedy that with long integration times and long averaging filtering. It shows out that K2001 suffer from severe low frequency "noise" i.e. short to medium term drift and i get much more useful volt nut style measurements with my Fluke 8845a using the statistics function and read average which gives 7.5 digit.What is the recommended setup of Keithely 2001 for as good as possible volt nut style measurements in terms of PLC, averaging filter, line sync and other settings? Any other tweaks that can be done?
Anyone have a manual for a Rapco 1804 L25C GPSDO ? - Page 1
Forum section: electronics / general

author: bingo600
author_rank: Super Contributor
timestamp: March 21, 2023, 02:53:57 pm
content: I just got a Rapco 1804L25C GPSDO3 x 10MHz Sine1 x 10MHz Square (TTL)1 x 1-PPS (TTL)Came w. a Trimble Bullet antenna (40dB) , and has never been setup.Does anyone have a manual for this guy ?I found one mentioning 1804L25 as one of the certificates , but it's a 5MHz unit , and doesn't mention the "Output valid" LED.I took some pics of the inside.Trimble SK2-8 GPSMorion MV62 OCXOAD7846 16-bit DACHD64180 MCUEPM7128 CPLD

author: bingo600
author_rank: Super Contributor
timestamp: March 21, 2023, 02:57:30 pm
content: More pics

author: bingo600
author_rank: Super Contributor
timestamp: March 21, 2023, 02:59:23 pm
content: More pics
Fluke 8508A 8½ digit reference dvm repair/recapping - Page 1
Forum section: electronics / general

author: mzzj
author_rank: Super Contributor
timestamp: March 15, 2023, 06:33:49 pm
content: Symptoms of the patient: 8508A gone bonkers, fails to zero on resistance ranges (error during input zero 2004)Being switched off for 30 minutes and it fails to start up properly, one of the lcd displays remains black and entire unit is nonresponsive.There is a signs of earlier butchered capacitor replacement on the power supply board, blue 50v 470uF electrolytics have been replaced before. Power supply seem to run rather warm (8508A doesn't have any sort of cooling fan.)On closer inspection the blue 50v 470uF caps measure fine on ESR but the 3300uF 35V snap-on electrolytics have 10 ohm ESR or about 500x higher than expected!One of the small 10uF 50v/63v electrolytics next to R514 also measures 1.5kOhm ESRhttps://xdevs.com/doc/Fluke/8508A/img_cm/Guts_3.jpg3300uF 35v snap-on electrolytics are some ultra-miniature series and I didn't have any in "stock".Quick&dirty repair with taller 2200uF 35V caps and the unit powers up fine, clears all self tests and runs through the zero routine just fine.Hopefully this is helpfull with someone working with these dinosaurs. I'd assume that these have come to mature age and failures are more of rule than exeption.Also question if someone has replaced or measured the electrolytic caps on the "monster relay board"?https://xdevs.com/doc/Fluke/8508A/img_cm/Guts_7.jpgThey also look like recipe for disaster being next to heatsinked components inside a rather hot running equipment.

author: Andreas
author_rank: Super Contributor
timestamp: March 15, 2023, 08:43:22 pm
content: Hmm,there seems to be more trouble left of the reference boardwith best regardsAndreas

author: mzzj
author_rank: Super Contributor
timestamp: March 16, 2023, 06:25:00 am
content: Quote from: Andreas on March 15, 2023, 08:43:22 pmPics in first post are not mine but the unit I was working on had exactly same bodge as shown in this xdevs pic:https://xdevs.com/doc/Fluke/8508A/img_cm/Guts_15.jpgDIP-8 opamp with different pinout mounted to SO-8 smd footprint

author: Ugur
author_rank: Regular Contributor
timestamp: March 16, 2023, 06:53:41 am
content: Hello,I tested it when I did a similar repair and it passed all the tests without any problems, but during the adjustment, the AC 200mV 60 kHz adjustment step could not pass.

author: mzzj
author_rank: Super Contributor
timestamp: March 16, 2023, 02:27:26 pm
content: Turns out most of the errors were not directly related to cooked caps. Unit started to misbehave once it warmed up and threw again dozen of ohms function related errors.Ohm range current supply was bit off(97...90uA) for 100uA 20kOhm current supply and it showed considerable drift.TIP32C transistors on A3 resistance measurement PCB run rather hot and PCB is slightly toasted in the general area of the transistors.Replacement of TIP32C transistors and nearest BC856A (SMD marking 3A) seemed to fix the the resistance function.
Calibration mode for Gdm-8341 - Page 1
Forum section: electronics / general

author: danilnik
author_rank: Newbie
timestamp: March 01, 2023, 06:23:48 am
content: Please help. Need to go into calibration mode for Gdm-8341. Or share service manual for gdm-83xx series. Thanks)

author: danilnik
author_rank: Newbie
timestamp: March 06, 2023, 10:00:24 am
content: If you turn it on while holding "shift", the device switches to some mode (in this mode, indications of all segments of the display are observed)the same, but with holding "range -"
Stanford Research PRS10C (Lady Heather 6.08) - Page 1
Forum section: electronics / general

author: Ohm_My
author_rank: Contributor
timestamp: August 02, 2018, 02:17:54 am
content: Hello All,I've been using LH along with my rubidium oscillator and am curious as to how LH retrieves the "Life" reading. I assume this is a total cumulative up-time reading for the unit. I did some extensive reading in the Service Manual for the PRS10C but did not see how to query for this value.Any assistance is appreciated.

author: texaspyro
author_rank: Super Contributor
timestamp: August 02, 2018, 02:46:09 am
content: The PRS10 firmware updates the FC value in EEPROM every 12 hours or on every power cycle. It also logs the counts in EEPROM. Do a little math on the numbers and you get an estimate on the power-on hours... a clever wench be Lady Heather! Estimate will be off if the device is not left on continually or you do a lot of manual writes of the FC value.

author: matthuszagh
author_rank: Frequent Contributor
timestamp: March 03, 2023, 11:47:59 pm
content: Quote from: texaspyro on August 02, 2018, 02:46:09 amWhere does 12 hours come from? The manual says:QuoteAlso relevant:QuoteSo to estimate the operation time, it seems like you'd take the 2nd number, subtract the first and that would give you the number of full days of operation. That ignores manual updates to the frequency control, so it's only accurate if the number of FC manual updates is sufficiently low.That said, the first two numbers from my unit's fc are: 79,10910. My estimate would imply 30 years of continuous operation, which seems unlikely. Yours gives more like 15 years, which seems much more reasonable.
ALTAI HC5050E - Page 1
Forum section: electronics / general

author: lionelkjh
author_rank: Frequent Contributor
timestamp: February 22, 2023, 03:05:03 pm
content: Hello everyone! I ask for your kindness to help me understand what potentiometers R33/R34 can do on an ALTAI HC5050E multimeter (see diagram opposite)....Thank you all for your help!

author: danilnik
author_rank: Newbie
timestamp: March 03, 2023, 09:29:38 am
content: R34, R35 are for balancing
Optronics 83DS vintage precision CCS - Page 1
Forum section: electronics / general

author: trobbins
author_rank: Frequent Contributor
timestamp: February 16, 2023, 07:53:54 am
content: I am aiming to reconfigure a circa 1985 Optronics 83DS precision current supply, as in common use in optical related labs as a reference lamp supply. Optronics have no remaining documentation on it, and I can't find any from when this was used. The internal electrical schematic should be fairly simple to reverse engineer, but I thought I would ask if anyone has anything related to this, or even any later model (83A) ?The front panel allows a constant current from 1mA to 9.999A to be set, but I don't even know the max voltage range spec yet although it's likely to be up to about 120V. The only known specs (I think) are +/- 0.05% current accuracy and the same for line/load regulation. So I may be able to retain its use as a lab precision current supply and see how good it is.Unfortunately the mains AC is 115V, and it is direct rectified and brute-force cap filtered, so not very elegant. I could end up running it through a step-down/isolation transformer, but I may be able to feed it from an alternative mains-isolated DC supply, and just live with a restricted output voltage and current span.

author: DavidKo
author_rank: Frequent Contributor
timestamp: February 27, 2023, 08:40:09 am
content: Try to ask Calcoast in the following listhttps://www.nhtsa.gov/vehicle-manufacturers/compliance-test-laboratories. They do the photometry testing so it can be that they are using Optronic devices. In Europe the labs often use LMT equipment.Voltage range should be 30-40V for 24V devices.

author: trobbins
author_rank: Frequent Contributor
timestamp: February 27, 2023, 01:12:05 pm
content: Thanks for that contact detail - I have emailed them.
A power meter for wireless power transfer system - Page 1
Forum section: electronics / general

author: RokKol5230
author_rank: Newbie
timestamp: February 02, 2023, 11:14:02 am
content: Hello Guys,For me, is needed some opinions about my project. Currently, I'm thinking about designing an embedded system for wireless charger high frequency primary circuit power monitoring then SS compensation topology is being used in charger. I'm thinking about using shunt for current measurements, because max ac voltage would be 1V and max current 1A. What do you think about that? Signal bandwidth 200khz

author: miro123
author_rank: Frequent Contributor
timestamp: February 03, 2023, 05:54:25 pm
content: What precision and accuracy do you want to achieve?

author: RokKol5230
author_rank: Newbie
timestamp: February 26, 2023, 12:15:40 pm
content: 2 % accuracy for power. Bandwitch 200khz. Voltage 0.1-1V, current 0.01 - 1A
Calibration procedure or service manual for Escort EDM-89S? - Page 1
Forum section: electronics / general

author: canis_lupus
author_rank: Newbie
timestamp: February 15, 2023, 04:09:27 pm
content: I have an old Escort EDM-89S multimeter. Recently, comparing it with a multimeter a few classes more accurate, I found that its voltage readings differ by as much as 3-4%. The device has many potentiometers inside, but unfortunately they are not described in any way. Maybe someone has a service manual or at least the calibration procedure for this device? I would like to give him a long life...

author: J-R
author_rank: Super Contributor
timestamp: February 16, 2023, 12:27:16 am
content: Can you post a photo of the PCB with the pots? It might help.Also, since the DMM is somewhat low-end and currently of little use, I would not be too worried about just tweaking things until you figure it out. You could make marks on the pots to indicate their current positions before your start.

author: canis_lupus
author_rank: Newbie
timestamp: February 16, 2023, 09:01:06 am
content: Some photos of PCB with pots:https://imgur.com/a/Tv9mk1wut this escort few years ago, it was an expensive and quite good device. Totally not amateurish.

author: mendip_discovery
author_rank: Super Contributor
timestamp: February 16, 2023, 09:17:14 am
content: Looks like a Tenma so you might find some info from them.

author: canis_lupus
author_rank: Newbie
timestamp: February 16, 2023, 09:32:09 am
content: Yes, similar model to Tenma 72-6255, byt with autorange... Thx! I'm looking in that way...

author: J-R
author_rank: Super Contributor
timestamp: February 17, 2023, 01:21:07 am
content: Wow, that is a lot of potential twirling, best of luck with your search for the calibration procedure. The one pot for the TRMS is probably a frequency-dependent adjustment.

author: J-R
author_rank: Super Contributor
timestamp: February 17, 2023, 05:33:48 am
content: Looking at some old catalogs on Archive.org, the Escort EDM-89S seems to have come out in the early 90s.Agilent purchased Escort in 2008.While some of the pots seem promising, like the ones labelled CX, I suspect given the number of functions and ranges that this DMM might require a more complex calibration procedure, perhaps involving some of the pins on the board. However, maybe there is still a chance, as it's only a 5,000 count DMM. Typically the variable capacitors are for AC functions.
Hamon Divider 100G 10G per step - Page 1
Forum section: electronics / general

author: VintageNut
author_rank: Frequent Contributor
timestamp: February 12, 2023, 05:06:56 pm
content: This is a germ of an idea. Lots of the prep work is already done.PCB is in the process of being fabricated.I will be using 1G resistors that I have sorted into pairs that are within ~200 ppm of 2G.This first attempt will not be guarded. It will have a triax jack on low side for minimizing leakage on the low side.I bough a 100M, 10M per step Hamon transfer standard to see how it works.I do not care about leakage on the high side. The PCB creepage will be minimized with 1mm wide slots.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: February 14, 2023, 09:10:06 pm
content: I would probably use PTFE stand-offs for this. If you prefer a PCB you may want to use the Rogers 4350B laminate, certainly not FR4.CheersAlex

author: DavidKo
author_rank: Frequent Contributor
timestamp: February 16, 2023, 05:47:27 am
content: Adding 1 resistor more (as in ESI transfer standards) will enable you to use it in KVD configuration.
Fluke 732A Power supply issue - Page 1
Forum section: electronics / general

author: Louis_C
author_rank: Contributor
timestamp: February 07, 2023, 07:07:05 pm
content: I have a Fluke 732A that I am repairing and I have a strange issue with the AC power supply. On the A4 board, test point 1 to test point 1 on the back plane board, I get 18.65v DC solid and steady (on battery, the batteries are new). When I switch to AC, I get 18.65v but, it will cycle down to 15.5v every 3 seconds. I can NOT get the cal light to come on, it just comes on for one second and goes out. I replaced ALL transistors on the A3 and A4 boards as well as the electrolytic caps and the rectifier. I still get the swinging voltage. Any ideas?

author: Simon
author_rank: Unknown
timestamp: February 07, 2023, 08:16:45 pm
content: I have reduced your triple post down to this one. Please try to keep it this way, you will quikly discover that people don't like replying to the same thing twice.

author: Okertime
author_rank: Contributor
timestamp: February 07, 2023, 08:46:39 pm
content: Does the position of the power-line switches S1 and S2 on the pre-regulator board A3 match your power-line voltage?

author: Louis_C
author_rank: Contributor
timestamp: February 07, 2023, 09:44:00 pm
content: Sorry for the multiple posts. I'm still learning the webpage layout, I don't blog but, I need help. Anyway, yes I have the switched set to 120volt AC. I have the service manual and checked that first. It's a strange issue and I NEED this unit up so I can cal our 5700A that I repaired. It's one problem after another it seems.

author: lowimpedance
author_rank: Super Contributor
timestamp: February 07, 2023, 11:29:11 pm
content: There may be some useful information in the thread linked below since you have just put new batteries in.https://www.eevblog.com/forum/metrology/fluke-732a-fluke-752a/msg1278667/#msg1278667

author: chuckb
author_rank: Frequent Contributor
timestamp: February 08, 2023, 12:28:59 am
content: The battery is not required for operation. How does the unit work without the battery?