hybridfree/eevblog-posts huggingface dataset:
xdevs.com Fluke 732A repair and modification pages - Page 1
Forum section: electronics / general

author: perdrix
author_rank: Frequent Contributor
timestamp: January 17, 2018, 07:48:31 pm
content: Todd Micaleff put up a page on xdevs.com about the 732A. However it seems incomplete.The page is here:https://xdevs.com/fix/f732a/Is this an error on the website, or a work in progress?ThanksDave

author: MisterDiodes
author_rank: Frequent Contributor
timestamp: January 17, 2018, 09:59:06 pm
content: Seems incomplete, but that unit has been discussed a lot on EEVblog.Did you have a specific concern or question?

author: TiN
author_rank: Super Contributor
timestamp: January 17, 2018, 11:17:24 pm
content: It is draft, work in progress.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: January 18, 2018, 06:06:55 am
content: Dave,This is a work in progress. It actually there are two 732A. One had a drift issue after an extended power outage and the other was a new to me reference that needed to be checked out. It also appears to be drifting a lot. The new reference has drifted 1.5ppm in 6 months.The pictures in the article are of the new to me reference. It currently has at least one problem. It will not enable the in cal LED. It worked when I first got it but now there is something wrong. The oven thermistor value seems steady.I am making a few changes and then collecting data.

author: Pipelie
author_rank: Regular Contributor
timestamp: January 18, 2018, 08:47:35 am
content: looking forward to reading it.

author: perdrix
author_rank: Frequent Contributor
timestamp: January 25, 2018, 07:10:38 pm
content: I'm also interested to follow this, I've just replaced the electrolytic capacitors on the two regulator boards, but haven't touched the oven.I did however change the jumpers on the calibration board as I was out of adjustment on the 10V potentiometer.So far (it's been on a week since I did that) and it seems to have stabilised. It was quite surprising to me how much it drifted initially - I had to adjust the 10V potentiometer about every day for the first few days to stay within 20uV of nominal.I hope it will now settle down.Dave

author: alm
author_rank: Super Contributor
timestamp: January 27, 2018, 08:10:34 am
content: Why would you adjust it every day? Would make more sense to just track the drift every day until it stabilizes, and only then adjust it? That would make it easier to track drift over time.

author: perdrix
author_rank: Frequent Contributor
timestamp: January 27, 2018, 04:43:49 pm
content: Because it drifted a HUGE amount - milli-volts, not micro-volts, and I thought on each occasion "That must have stabilised now" - but I was wrong (until about day 5).Dave

author: TiN
author_rank: Super Contributor
timestamp: January 28, 2018, 11:51:04 am
content: References that were cold for long time not rare to take weeks and months to get stable again. So I wouldn't even expect anything before first month.That is why all serious references are battery-backed, so even during shipping they can keep the power.
RS-232 interface for GPS timing receivers - Page 1
Forum section: electronics / general

author: texaspyro
author_rank: Super Contributor
timestamp: December 20, 2017, 02:27:21 am
content: Long ago, I did a small board for interfacing the Trimble Resolution-T timing receiver to an RS-232 interface with support of the 1PPS output on pin 1. It also has connectors and mounting holes for the Adafruit Ultimate GPS and CN06 Ublox Neo-6 receivers. Nick Sayer's Venus Skytraq timing receiver board (on Tindie) is pinout compatible to the Adafruit. It's very easy to wire up to other GPS modules that have logic level serial ports. For some strange reason, I've been getting several requests for more info on the board. I'm not going to be building any, but you can. Here is a link to a more detailed thread:https://www.eevblog.com/forum/projects/rs-232-board-for-gps-modules-(trimble-resolution-t-adafruit-cn06-etc)/new/#new
Connector grades as per video #1039 - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: December 17, 2017, 02:43:58 am
content: In one of the videos (#1039), Agilent technology calibration manager talks about different grades of connectors. Metrology grade, instrument grade, and field grade to be exact. So I headed over to Amphenol catalog and tried to identify which one is which. I have instruments up to 2 GHz. My concern is, I definitely don't want to damage the connectors, and if (as the video says) it can make up to 20db difference by repeatedly using field grade connectors on instruments, I better avoid using field grade.To my surprise, none of them are identified as "grades".My particular interest is going from N female to BNC female. There are at least 5 different kind of connector of this type. Would anyone be able to help me which is which? I know RFX grade means "commercial". Then, there is a lesser priced one without RFX designation which meets MIL spec. Then there are ones that has to be ordered in quantity of 100s.Can anyone assist me on this?

author: darrell
author_rank: Regular Contributor
timestamp: December 18, 2017, 12:30:12 am
content: Get something decent quality and you will be fine. N connectors are rugged. What he said about damage applies more to 3.5 mm and smaller. The most important thing is to avoid mating questionable SMAs with precision 3.5 or 2.92 mm. A cheap adapter from Ebay (some truly horrible connectors there) is likely to get you a broken connector on your equipment, but that's unlikely with anything from Amphenol or similar. Most of what Digikey and Mouser carry is field grade, but that's likely OK for your application.Things to look for in a precision connector: stainless steel or BeCu outer conductor (not plated brass), BeCu inner contact, no slots in the outer of an N.Repeatability won't be great with BNC in any case. I'm assuming the mention of 20 dB difference is in relation to return loss, which would cause transmission to change by something like 0.05 dB.Inmet 5131, Rosenberger 53S151-K00N5 or Pomona 3288 would be decent options. I'd consider the last two to be field grade.This is an excellent resource from NPL:http://www.npl.co.uk/anamet-connector-guideThere's also IEEE-287, but it's behind a paywall.

author: tkamiya
author_rank: Super Contributor
timestamp: December 18, 2017, 02:37:21 am
content: Thank you.I think I'm going to go with Amphenol standard type. Yes, mention of 20db was a return loss.....
Russian Transfer Standard B1-30 - Page 1
Forum section: electronics / general

author: zhtoor
author_rank: Frequent Contributor
timestamp: December 15, 2017, 08:01:58 pm
content: Hello,any body with teardown or other information about this ref?specs:-The reproducible voltage is 9 ± 0.45 V.The instability of the reproducible voltage for every 1000 h at a temperature of 20 ± 5 ° C is 0.0005%.Additional temperature error is 0.000025% / ° C.The time for setting the operating mode is 4 hours.The output resistance is 15 ohms.Power consumption - 8 V ??· A.The overall dimensions are 151 × 86 × 79 mm.Weight - no more than 1.2 kg.regards.-zia

author: wraper
author_rank: Unknown
timestamp: December 15, 2017, 08:37:25 pm
content: Zener diode datasheet:http://www.eandc.ru/pdf/stabilitron/2s108g-r.pdf

author: Mickle T.
author_rank: Frequent Contributor
timestamp: December 16, 2017, 06:32:17 am
content: I have a two V1-30. They are rather old and noisy (1 ppm p-p 0.1-10 Hz), but fairly stable and gives ~1-2 ppm/3 years drift rate in power off mode.

author: beanflying
author_rank: Super Contributor
timestamp: December 16, 2017, 08:04:36 am
content: Wonder how much of the noise comes from the Transformer and power supply inside the same box?

author: zhtoor
author_rank: Frequent Contributor
timestamp: December 16, 2017, 09:12:32 am
content: thanks Mickle T.a wonderful design for the time...regards.-zia
Valhalla 2703 ROM firmware - Page 1
Forum section: electronics / general

author: texaspyro
author_rank: Super Contributor
timestamp: December 11, 2017, 01:45:16 am
content: Attached is a ROM dump of the firmware in my Valhalla 2703 AC calibrator. I dumped it years ago and mentioned on volt-nuts that I was going to do it. I've gotten a few requests from that post.

author: quarks
author_rank: Frequent Contributor
timestamp: December 12, 2017, 10:38:01 am
content: can you tell which version this is?thanks a lot for sharing

author: texaspyro
author_rank: Super Contributor
timestamp: December 12, 2017, 04:16:38 pm
content: Quote from: quarks on December 12, 2017, 10:38:01 amNot at the moment. I don't remember and the unit is currently elsewhere.
Guildline low thermal selector switch teardown - Page 1
Forum section: electronics / general

author: doktor pyta
author_rank: Frequent Contributor
timestamp: December 11, 2017, 10:20:32 am
content: Guildline low thermal selector switch model 9145A10.The position (0 or 90 degrees) of switch marked with two dots determines if the whole set is locking or momentary.Some old papers found in google books claim this model is specified as +/-10nV thermal EMF. Nice.Have a tea and watch

author: doktor pyta
author_rank: Frequent Contributor
timestamp: December 11, 2017, 10:23:51 am
content: 2

author: doktor pyta
author_rank: Frequent Contributor
timestamp: December 11, 2017, 10:25:09 am
content: part 3

author: TiN
author_rank: Super Contributor
timestamp: December 11, 2017, 11:01:11 am
content: Thank you. Interesting design with silver (?) bars. Copper lugs to equalize temperature, while silver pad to provide low resistance contact?

author: RobK_NL
author_rank: Frequent Contributor
timestamp: December 11, 2017, 03:22:45 pm
content: Heh, I've got its little brother here; the 5-channel 9145A.Quote from: TiN on December 11, 2017, 11:01:11 amYes, those contacts are silver. But I've always wondered about the design, especially concerning the "low resistance" part.Those silver bars are almost 10mm long, but the bars on the plungers are round, so the actual contact area is only a few 10ths of a mm.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: December 11, 2017, 03:23:58 pm
content: I may be wrong but it does not look like pure silver, rather some harder alloy. The shorting rods are mounted on flat springs so the contat is self-cleaning.

author: manganin
author_rank: Regular Contributor
timestamp: December 11, 2017, 03:39:54 pm
content: Quote from: doktor pyta on December 11, 2017, 10:20:32 amAs far as I remember, repeatability of something like a few hundred nanovolts can be achieved. But soon you will have a nanovoltmeter to do the tests...Rather than low thermal I would call these high reliability switches. In addition to the contact pressure the spring also produces small wiping action cleaning the silver alloy oxidation.Very long life, even when operated by solenoids.
HP 4470A transistor noise analyzer manual - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: December 09, 2017, 07:24:28 pm
content: Hello,I am looking for the manual of HP 4470A transistor noise analyzer. I have found the B manual but there is a lot of différences between A and B. (purpose : select transistors for a cal project !). Thank you.
Datron 4920 service manual - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: November 29, 2017, 10:16:11 pm
content: Hello,I have joined the club of the Datron 4920 owners but mine is without the M suffix. I have read the big topic devoted to the 4920 and 4920M but it is entirely speaking about the M. I have obviously 2 blown resistors on the ADC board but my board has a lot more components and is quite different from the one (M) pictured. Therefore I am looking for the service manual of the 4920 without suffix. Thank you.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: November 30, 2017, 01:03:26 am
content: None available and I have looked. I bought the 4920M manual in hopes it would help but it is limited.If you need pics of the good resistors, I can help. Upload some pics of the areas with the bad resistors and I can take photos of them.Did yours come with the option 10?

author: jfphp
author_rank: Regular Contributor
timestamp: December 06, 2017, 11:21:00 pm
content: Thanks for offer. Unfortunately I quickly went out of the club : the 4920 was totaly out of service : no display at all and I sent it back to the seller. Perhaps to a next occasion...
Four KOEP Trancell VI DC Voltage Reference Standards, VTS6001-1, tested good - Page 1
Forum section: electronics / general

author: branadic
author_rank: Super Contributor
timestamp: December 10, 2017, 08:09:16 pm
content: For all of you with the available budget that need some quad reference for LTZ1000 comparison, have you seen this offer?https://www.ebay.com/itm/Four-KOEP-Trancell-VI-DC-Voltage-Reference-Standards-VTS6001-1-tested-good-/282736732277-branadic-
3458A noise performance - Page 1
Forum section: electronics / general

author: alanambrose
author_rank: Frequent Contributor
timestamp: November 30, 2017, 04:49:39 pm
content: FYI I just came across these:https://www.researchgate.net/publication/306114861_Keysight_3458A_noise_performancehttps://www.researchgate.net/project/Writing-the-book-Sampling-with-3458AI've asked for a copy of the paper.Alan

author: Echo88
author_rank: Frequent Contributor
timestamp: November 30, 2017, 06:24:56 pm
content: Evil persons could also usehttps://sci-hub.bz/

author: cat87
author_rank: Regular Contributor
timestamp: November 30, 2017, 07:56:37 pm
content: And as a quick hint, you should search on sci-hub for the the article's DOI. Seraching for it by name isn't going to brig up any results. At least, for my searches it never does

author: dl1640
author_rank: Regular Contributor
timestamp: December 02, 2017, 10:40:02 am
content: Quote from: alanambrose on November 30, 2017, 04:49:39 pmDo they reply?
GPSDO Ensemble yes or NO - Page 1
Forum section: electronics / general

author: Theboel
author_rank: Frequent Contributor
timestamp: November 27, 2017, 01:47:48 am
content: Hi All,Friend of mine offer me to buy 5 GPSDO its HP 58503A the price is ok (60USD each) all of them have HP 10811 inside but I have some difficulties how to use 5 of this so here the option :1. buy it and then select the best one and keep it2. made an ensemble of it3. send one of them to NMI and calibrated4. buy just 1 and hope the best ?what You think the best option ?and I have a few more question :1. My best freq counter is CNT 90, my best OCXO is wenzel low noise OCXO, My best Rubidium is LPRO-100 so how to choose the best from this 58503A for my next reference before next step ?2. in case the ensemble of 5 58503A is the best option how to arrange it ? and how to use the ensemble ?Thank You

author: edpalmer42
author_rank: Super Contributor
timestamp: November 27, 2017, 03:23:03 am
content: I can't really make any suggestions on whether you should buy them all. You know what your budget is like, I don't. $60 each is a very good price. They do look a bit rough, but that could be just dust and dirt. I'm guessing that the humidity is high where you are. Is there any sign of rust? One thing to remember is that due to their age, they might report the wrong date due to the 1024-week rollover bug that affects all GPS Time/Frequency receivers. This only becomes an issue if you wanted to use one with an NTP server and even then, there are often workarounds.Once you decide how many to buy, the fun begins. Of course, you have to test them all. Even if they all work, wiser people than me have stated that 10811 oscillators are not created equal.http://www.leapsecond.com/pages/z3801a-osc/. Your CNT-90 counter and Wenzel oscillator should be able to determine which is best. Use Timelab to collect the data.I don't see the point in sending out for calibration. I don't know what that would consist of, but if your tests show that it works, then it works. What more could a cal lab do?I'm not familiar with the advantages of an ensemble, but the idea of an ensemble of identical units sounds like a lot of work for limited return. An ensemble of different units would have different strengths and weaknesses and so would have a bit more value, but it still sounds like a lot of work for limited return.I suspect that, if the budget allowed, most people would buy them all, keep the best 2 or 3 and sell the others.Ed
Fluke 8846A Lithium Battery Replacement - cal data affected? - Page 1
Forum section: electronics / general

author: KJ-90
author_rank: Contributor
timestamp: November 20, 2017, 05:01:40 pm
content: In the Fluke 8846A DMM, there is a lithium coin cell on the main circuit board. I have read this is for powering the unit's clock and calendar functions. However, does it also affect the calibration data retention as well? As we know, most closed-case calibrated equipment stores the cal data in NVRAM, so no battery power is needed. But, is it safe to change the cell if needed, or is this only a Fluke service center task? Any ideas on what to do when the battery needs replacing?

author: Awesome14
author_rank: Regular Contributor
timestamp: November 22, 2017, 01:47:20 am
content: The service manual for the 8846A is called the 'calibration' manual. It doesn't mention the button cell. But page 1-7 of the user manual mentions that calibration constants are stored in non-volatile memory.

author: macboy
author_rank: Super Contributor
timestamp: November 24, 2017, 02:43:56 pm
content: Quote from: Awesome14 on November 22, 2017, 01:47:20 am'Non-volatile" definitely can mean battery-backed RAM.If you are confident in your ability to not hurt yourself doing it, you could consider changing the battery with the power on. I don't recommend it though.
A couple of 3458a for sale - Page 1
Forum section: electronics / general

author: IconicPCB
author_rank: Super Contributor
timestamp: November 21, 2017, 10:29:00 pm
content: http://www.go-dove.com/en/events?cmd=details&event=561312&utm_source=Eloqua&utm_content=e1&utm_medium=email&utm_campaign=gidb_2018_q1_nov_emea_en_561312_ia_e1_bpem_biotech

author: MK
author_rank: Regular Contributor
timestamp: November 21, 2017, 10:46:10 pm
content: I tried to use them a while ago, but bidding and fees seemed complicated, also shipping impossible to work out in advance. Tried to use the geographic search on their site could never get it to work right, so gave up trying to use them, then found they would not honour list removal requests!
How to measure HV DC power supply ripple voltage? - Page 1
Forum section: electronics / general

author: 001
author_rank: Super Contributor
timestamp: December 04, 2017, 03:24:41 pm
content: Power Supply rated as 480volts 180mA DCRipple voltage (saw waveform) range about tens millivoltsHow to measure ripple voltage and not destroy any gear?

author: e61_phil
author_rank: Frequent Contributor
timestamp: December 04, 2017, 03:32:03 pm
content: With AC-coupling.Be careful, most scopes have a DC high-impedance if you switch them to AC-coupling. In this case, the scope will see the full DC voltage even if you use a 1:100 probe.I've build an AC-coupler to measure noise on voltages of up to 10kV. The design is very simple: In front is a coupling capacitor followed by a 9Meg resistor. A variable capacitor is used to trimm the capacities. This gives a flat frequency response from below 1Hz to 10MHz, which is way more than I needed.

author: David Hess
author_rank: Super Contributor
timestamp: December 04, 2017, 07:07:26 pm
content: Quote from: e61_phil on December 04, 2017, 03:32:03 pmThey are rare now but good x100 probes include an internal shunt preventing this problem. They can be identified by having a specified input resistance which is less than 100 megohms. A good example is the old Tektronix P6009 x100 probe which has a 10 megohm input resistance.But a standard dividing probe is the wrong way to make this measurement. Do what e61_phil suggests and make an external high voltage DC block with the needed frequency response.

author: eliocor
author_rank: Unknown
timestamp: December 05, 2017, 12:07:14 am
content: take a look at AN-118 from Linear Technology:http://www.linear.com/designtools/app_notes.phpPlease READ IT ALL !!!
LCR meter / What frequency? - Page 1
Forum section: electronics / general

author: 001
author_rank: Super Contributor
timestamp: November 11, 2017, 05:55:06 pm
content: Anower stupid questionsorryBut I see You can helpHow to choose right test frequency for LCR measurment?For exampleI`m gonna use DE5000I see what simple resistor has different impedance at 120Hz and 100kHz (But NOMINAL resistance is for DC, isnt it?)And what about frequency to measure capacitors and coils accordings to its NOMINAL values?Thanx

author: ataradov
author_rank: Super Contributor
timestamp: November 11, 2017, 07:31:15 pm
content: Chose it according to your target application.

author: jfphp
author_rank: Regular Contributor
timestamp: November 20, 2017, 11:37:29 am
content: For a resistor nominal test DC. But, it could be 18Ghz or 20 Khz, depending of your application.For capacitor or self, nominal test is usually1 Khz or 100/120 Hz above 100000pf. Refer to the datashet of the manufacturer : it gives the conditions of mesurement. Again it could be 18 Ghz... (for instance chip capacitor for microwave : usually in form of S parameters)

author: tggzzz
author_rank: Super Contributor
timestamp: November 20, 2017, 11:50:19 am
content: Quote from: 001 on November 11, 2017, 05:55:06 pmAny generic component test isn't directly relevant. All that is relevant is how a component performs in your circuit.Hence it helps, but no more, to choose a tests that are the same as your circuit.There is, and always has been, a great deal of specmanship on the part of suppliers and interpolation/extrapolation on the part of users. The most extreme case I've seen is extrapolating from how an audio component tested at 1.6kHz works at 2Mb/s. The user didn't want to get the supplier to change the component's tests, since that would have allowed the supplier to increase the price.

author: HighVoltage
author_rank: Super Contributor
timestamp: November 20, 2017, 12:14:37 pm
content: Many older LCR meters could not change the frequency and were fixed at 1000 Hz.That is why, if you look at older datasheets of components, they all got tested at 1 kHz.
Audio measurings - Page 1
Forum section: electronics / general

author: 001
author_rank: Super Contributor
timestamp: November 15, 2017, 07:58:53 am
content: Hi!I'm repairmanAll the time I check amps, deck, etc with scope and tube voltmeterI use simple single wires nowNow I want to "level up" my shop. Is it nesessary to plug coaxial cables to all gear? Can simple shielded cable substitute coaxial for audio works? Audio connectors didn't have specific 50 ohm grade (common for fg and scopes).

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: November 15, 2017, 04:28:27 pm
content: Cable impedance is of almost zero concern in audio work. Coaxial cable = shielded cable. Sometimes you have to disconnect ground on one end of a cable to prevent ground loops or pickup. I find grounding is most important for low distortion measurements, and the best method is not always obvious. Many times twisted pairs will work just as well as coaxial.In crazy-nutvolter land, currents are usually low unless it's a current measurement actually being made. OTOH, voltages are usually high enough to be out of the noise. In crazy-audiophile land I find the more common problem is having enough scope gain to see the things I care about, signals on ground lines. An old scope with a differential plug-in serves me better than the latest digital thing. It's nice to be accurate, but anything beyond a couple decimal places is usually overkill. Exceptions might be power measurements, where the result is a squared function, or RIAA accuracy, which is much harder to do well then most people think. An adjustable precision ratio transformer comparison is probably best, but not many people have those anymore.Audio is my first love and there's a lot of capacitor and other info on my web site that's geared to audio.

author: Gyro
author_rank: Super Contributor
timestamp: November 15, 2017, 08:32:42 pm
content: Is this any different to the questions that you've already asked in your other thread?https://www.eevblog.com/forum/beginners/is-rg58-cable-affordable-for-oscilloscope-probes/
Proper AC Power Protection For Calibrators and 6.5 & 8.5 Digit DMMs - Page 1
Forum section: electronics / general

author: KJ-90
author_rank: Contributor
timestamp: November 20, 2017, 04:54:55 pm
content: I've always wondered what brand and type of 120 VAC 60Hz surge protector and on-line dual-conversion sine wave UPS should be used for powering calibrators, and 6.5 & 8.5 digit DMMs. I don't presently own any of these instruments, but I'm wondering about a future 6.5 digit DMM. The well-known book Fluke Calibration Philosophy In Practice gives only general advice ( check the chapter called A Rogue's Gallery of Parasitics, I think ), but also Fluke hasn't issued a new edition of that book. My copy dates as of 1994, and I'm also wondering why a new edition of that book hasn't come out yet- is everything online now? The real concern that I have is finding a good quality Mode 1 surge protector ( I'm not sure if the Mode 2 protectors are suitable ), that other people have been satisfied with. In the case of the UPS system, the only issue is a low EMI figure and avoiding any ground loop problems. Does the community have any ideas?

author: HalFET
author_rank: Frequent Contributor
timestamp: November 20, 2017, 05:14:10 pm
content: I somewhat question the need to have a UPS for a 6.5 digit. That'll be a LM399 based one most likely, so just turn it on an hour or two before use and you ought to be fine. Now for calibrators and 8.5 digit monsters it is a different story!

author: Awesome14
author_rank: Regular Contributor
timestamp: November 22, 2017, 01:26:57 am
content: I use a Liebert GXT23000120 UPS to power the instrument rack, except for the DC power supplies. Line conditioners and surge protectors have a slightly delayed response time. A UPS absorbs everything before it can get through.

author: dl1640
author_rank: Regular Contributor
timestamp: November 24, 2017, 10:54:03 am
content: Does anyone just power it up directly from the mains socket, like I do?I think I should need a stable power source and it is expensive. And I might need some really good noise cut device if the power is too noisy.However in most cases I do not came across big issues but once I had trouble with unstable reading by a handy ohmmeter which is powered by a switch mode power supply connected directly from mains, but if the switch mode power supply is connected to a voltage regulator or the meter is power by batteries then the ohm reading will be stable.I admit the power quality from mains sucks, here
I would love to see hobbyists apply for this job... - Page 1
Forum section: electronics / general

author: Moon Winx
author_rank: Regular Contributor
timestamp: November 22, 2017, 01:58:01 am
content: https://www.usajobs.gov/GetJob/ViewDetails/484608500The wealth of knowledge and enthusiasm I see here makes me think some of you would make an excellent candidate for this position. If you put in for it, send me a PM. I don't have any authority in the hiring process but maybe I can put in a good word.

author: IanB
author_rank: Super Contributor
timestamp: November 22, 2017, 02:03:53 am
content: There are so many hoops to jump through to qualify for that job, I would be amazed if even one person in the whole of the USA can qualify(OK, probably a few more than one, but there's a really limited field of candidates.)

author: Awesome14
author_rank: Regular Contributor
timestamp: November 22, 2017, 02:28:10 am
content: I'm not eligible.

author: Dubbie
author_rank: Unknown
timestamp: November 22, 2017, 02:33:51 am
content: Why do you think a hobbiest would be suitable for the job? nothing at all in the job description makes me think that.

author: EEVblog
author_rank: Unknown
timestamp: November 22, 2017, 02:34:06 am
content: I love military gear and used to think that working on ships or other stuff would be cool, so I took an electronics job at Garden Island naval base in Sydney. Turned out it was as boring as bat pooContractors that I later ended up working for (GEC, Sercel, Thales) that were more removed from the actual military establishments, were far less boring.

author: IanB
author_rank: Super Contributor
timestamp: November 22, 2017, 02:43:10 am
content: Quote from: EEVblog on November 22, 2017, 02:34:06 amWhich I recently learned is pronounced "tah-liss" (not "thales"). Just a little nugget to hide away in the back of the mind until needed...

author: Moon Winx
author_rank: Regular Contributor
timestamp: November 22, 2017, 03:14:20 am
content: This lab is one of the few places in gov't that has zero contractor positions. In other words, it is completely hands-on and they give you a lot of freedom and resources to pursue projects that will benefit the lab's mission. It's not a contract management position.I really wish they would open it up to all US citizens, but that's really rare. I was just posting this just in case someone here may qualify and be interested. We've hired engineers before that had zero interest in metrology, and never really developed one, so to me it's a good idea to poll a group that loves this shit for the off-chance we can find someone talented in analog electronics design and would love pushing the boundaries in metrology.

author: IanB
author_rank: Super Contributor
timestamp: November 22, 2017, 03:18:49 am
content: Quote from: Moon Winx on November 22, 2017, 03:14:20 amThe fact that they restrict the applicant pool is good for the world at large since they are less likely to hire the best people, which sets the USA back in terms of its military advantage against other nations. It's all good
Lubrication of EDC MV 105 rotary switches - Page 1
Forum section: electronics / general

author: Shark
author_rank: Contributor
timestamp: November 09, 2017, 07:58:38 pm
content: Hi, I recently bought an old EDC MV 105. I noticed that rotation of the dials is not smooth.Looking at the service manual, "EDC 2008" lubrication is recommended. Pretty sure I cannot obtain this.Could anyone recommend a modern equivalent?Thanks!

author: iainwhite
author_rank: Unknown
timestamp: November 09, 2017, 08:22:40 pm
content: More recent (e.g. Krohne-Hite E100-RC) manuals recommend DeOxIT-D5 to clean and PreservIT-P5 to lubricate. I think PreservIT is now called DeoxIT Shield. Produced by Caig Laboratories.LookHere
DIY resistance standard banana plugs - Page 1
Forum section: electronics / general

author: wizard1
author_rank: Contributor
timestamp: November 08, 2017, 12:32:20 am
content: I'm putting together the parts for a build of Dave's resistance standard and had a quick question. It looks like Dave used some Pomona style binding posts for his, are these the 3770 model or a knock off? I bought some binding posts off of ebay for this only to realize the resistance of the binding posts will contribute to the overall reading. I assume higher quality binding posts are called for here?Thanks for the help!

author: e61_phil
author_rank: Frequent Contributor
timestamp: November 08, 2017, 09:18:29 am
content: I've used the Pomona ones. And you should use four plugs instead of two for resistance below 100k.
So old vs "aged" components? - Page 1
Forum section: electronics / general

author: 001
author_rank: Super Contributor
timestamp: November 04, 2017, 04:00:54 pm
content: Hi!I found few NOS precision bifillar wirewound resistors from 1976 (0.01% 0.03% 0.5% termal coeff is 1.6*10^-4)Is it shame or bargain?Since it "aged" how I can solder it? (What about stability after new soldering?)

author: Kleinstein
author_rank: Super Contributor
timestamp: November 04, 2017, 04:28:01 pm
content: A TC of 160 ppm/K would suggest that these are power resistors and not precision resistors. It is odd to make 0.01% tolerance ones with such a high TC.With precision wire would resistors it is a good idea to keep the contact area where the resistor wire contacts the contact wire cold anyway. This also applies to new ones. The wire itself will not get hot anyway. So this usually means avoid short leads and use something like pliers to cool. Depending on the temperature excursion during soldering there might be a new relaxation cycle started. However for some type already moving to different humidity level might be enough.

author: 001
author_rank: Super Contributor
timestamp: November 04, 2017, 06:04:01 pm
content: Thank You!I solder it nowWhat about "relaxation cycle" time?When I can use my DIY divider?
Data Proof 320A on eBay - beware - Page 1
Forum section: electronics / general

author: dr.diesel
author_rank: Super Contributor
timestamp: November 02, 2017, 05:08:33 pm
content: After forever waiting, (3) Data Proof scanners hit eBay not long ago, a couple 160s and a 320, so I bought the 320. Received it yesterday only to find all the cards/relays were gone and rear terminal wiring just cut! Seller was very understanding and quickly offered a return, I am confident they were not being deceitful, just pushing used gear fast by non-technical people.But anyhow, if it ends up on eBay again, don't want anyone else to run into the same issue, SN=353.
Calibrate HP 6612C ? - Page 1
Forum section: electronics / general

author: JohnPi
author_rank: Regular Contributor
timestamp: October 30, 2017, 03:19:01 am
content: I'm trying to calibrate my 6612C System Power Supply.I'm being lazy and not connecting to the rear force/sense terminals -- just until I can prove to my self that I can calibrate, then I'll use those.I can get into Cal mode (via the front panel, or GPIB) and calibrate the voltage and high current range. However when I enter the CAL:LEVEL P1 and then CAL:DATA data value, I get an OUT OF RANGE ERROR. The calibration setup shows to use a 400 ohm R in series with an ammeter -- so it seems that the precise value of the 400 ohm can't be that critical -- I get about 40 mA. No matter whether I enter the value as 0.040, or 40.0, I still get that error.Any ideas/help ?

author: TiN
author_rank: Super Contributor
timestamp: October 30, 2017, 03:57:56 am
content: Sure, you need to read manual more carefully and use correct resistor.

author: dacman
author_rank: Frequent Contributor
timestamp: October 30, 2017, 04:30:04 am
content: Carefully read Table B-1, and read what is inside the rectangle below Figure B-1 B. For calibrating the low current range, it's supposed to be a 1.1 kOhm resistor. The 400 Ohm is for verification.

author: HighVoltage
author_rank: Super Contributor
timestamp: October 30, 2017, 10:01:03 am
content: My first attempt to calibrate my 6612C also failed.But if I remember right, there was a mistake in one of the steps and one ENTER step was missing in the instructions. This becomes obvious, if you follow it. At the end it worked all out for me.
DSO waveform generator fn: output current - Page 1
Forum section: electronics / general

author: raff5184
author_rank: Regular Contributor
timestamp: October 28, 2017, 02:25:46 am
content: Hi all,I have a Keysight DSO X 3024A. It has a built in waveform generator. Unfortunately I wasn't able to find in the datasheet the output current when I apply the waveform to a load, supposed that the load is matched. I know that I can choose between a 50load or a 1Mone but nothing is said about the current.How should I deal with this issue? The current is important because I have to be careful with the amount of power that I am injecting into the loadThank you

author: technogeeky
author_rank: Frequent Contributor
timestamp: October 28, 2017, 02:38:11 am
content: Quote from: raff5184 on October 28, 2017, 02:25:46 amI'm not sure why this is in metrology, but the datasheet for that oscilloscope says the actual output impedance is 50 ohm. All of the voltage ratings are listed for the High-Z (1M ohm) output, at 5Vpp. So at 50 ohm, the output voltages are 2.5Vpp.I think this implies that maximum current is is 50 mA (2.5 Vpp / 50 ohm). Or 100 mA (5 Vpp / 50 ohm).
FLUKE 289  - Page 1
Forum section: electronics / general

author: kardacz
author_rank: Contributor
timestamp: August 18, 2016, 09:13:05 am
content: Hello everyone! I have a Fluke 289 that is down: after startup, four dashes are displayed, but no action appears! Even by regulating the hour, or by putting a laboratory power supply with 9V .... anyone have you any idea

author: kardacz
author_rank: Contributor
timestamp: August 18, 2016, 09:18:46 am
content: here are the photos....

author: Jacek_Paw
author_rank: Contributor
timestamp: August 18, 2016, 11:30:36 am
content: Hi,Fluke 289 has life time warranty but, it covers original purchaser only. In this case try service center.Looking by the fault moast probably sth. has happened with the firmware - try to update it, maybe it will help.Jacek.

author: kardacz
author_rank: Contributor
timestamp: August 18, 2016, 05:19:50 pm
content: Good evening; Thank you for your answers! Multimeter on the card is the integrated system: M430F448; and I think he's dead! .Pensez Sure it is programmed by Fluke?

author: kardacz
author_rank: Contributor
timestamp: August 18, 2016, 05:23:36 pm
content: Good evening; Thank you for your answers! Multimeter on the card is the integrated system: M430F448; and I think he's dead! . Are you programmed it Fluke

author: Jacek_Paw
author_rank: Contributor
timestamp: August 18, 2016, 08:05:43 pm
content: I suspect that the uC is not dead because date, time and bottom part is displayed correctly. Hard to say what is going on, based on my experince with Fluke 867 I would check the knob positioning circiut - it seams that the uC doesn't know the knob position, but I'm only guessing.Please post photos of main board maybe someone will spot something.BTW: Are you from Poland? (your nick sounds polish).

author: kardacz
author_rank: Contributor
timestamp: August 19, 2016, 05:33:09 am
content: Hello, thanks for your help! The integrated circuit is defective well as soldered to the map he presented many short circuits, I do not know is whether it is well programmed M430F448 Fluke? Someone should he you an idea ?? I attached a picture of the card ....

author: kardacz
author_rank: Contributor
timestamp: August 19, 2016, 05:36:25 am
content: there she is

author: sunfire
author_rank: Contributor
timestamp: October 25, 2017, 05:50:47 am
content: Have you fixed the meter yet ? If you haven't fixed it and you still have it, are you willing to sell it for parts ?I need some Fluke 289 parts and it\s more economical (for me) to buy a complete broken meter than buying all the parts separately.I tried sending you a PM but you're not accepting PMs ...Sorin
EDC MV116 Adjustment - Page 1
Forum section: electronics / general

author: Rbastler
author_rank: Frequent Contributor
timestamp: October 23, 2017, 06:28:35 pm
content: Before this weekend I brought my MV116 into the university cal lab, so it could warm up for two days. Today I performed the adjustments described in the manual I found online and now I wanna share the results.Adjust the zener voltage to the one written on the sticker inside the case.Offset, measured at output: 0.13568mV to 0.00066mV.Offset 2, Sense Offset, open link between black terminals, measure between them and adjust to <1mV: 0.11579mV to 0.00279mV.Feedback current, adjusting for 1V on second decade: 0.999981V to 1.0000004V.Now all done on first decade.Linearity at 2V: 1.999919V to 2.000001Vat 1V: 1.000017V to 1.000001Vat 4V 4.00014V to 4.000003Vat 6V 6.000051V to 6.000002Vat 8V 8.000137V to 8.000001Vat 10V: 9.999995V to 10.000002VFull scale 1V: 1.000040V to 1.000002V100mV: 100.06715mV to 100.06240mVAll done in a temperature stable room at 23.5° +-0.5°, with a HP3458A calibrated last time around seven years ago. So its by no means perfect, but totally fine for my home lab. At first I thought my unit was broken, because I coudnt get the "Offset 2" under 1mV. Then I found out that the trimmpot that I thought is for overcurrent protection is for the "Offset 2".I change the electrolytic caps. The foto used is a older one.I also measured every range with each setting on the first decade too.RB
Fluke 8842A input capacitor? - Page 1
Forum section: electronics / general

author: FrankBuss
author_rank: Unknown
timestamp: October 19, 2017, 10:00:46 pm
content: Irecently found outthat my Fluke 8842A has an input capacitor of about 650 nF when measuring DC voltage. Couldn't find this inthe manual. Is this normal? The manual specifies only 100 pF for AC voltage, if I didn't miss it. Looks a bit high to me. And I couldn't measure it with an external DMM, but it behaves like this when charged and then discharged with an external resistor.

author: mimmus78
author_rank: Unknown
timestamp: October 20, 2017, 09:08:19 am
content: There you go!As you posted this question here instead of the repair subforum what I can tell you is that there is no way to recover from this.I've seen many of 8842A with this cap busted, it's unobtanium, only thing you can do is to salvage the internal reference for building some voltage reference.(OK it's a joke, but I cannot resist).

author: Tektron
author_rank: Contributor
timestamp: October 22, 2017, 08:16:48 am
content: My 8842 has 2.5 nF at ranges 20 and lower (unstable and go bit low to 2.3 nF at fast measurement rate) and 76 pF at ranges 200 and 2000 in DCV mode. In the ACV mode it has 0.223 nF at all ranges. Measured with Tektronix TX3.

author: FrankBuss
author_rank: Unknown
timestamp: October 22, 2017, 10:58:23 am
content: Quote from: Tektron on October 22, 2017, 08:16:48 amAre you sure about this? I tried to measure the input capacitance with an external DMM (BM257s) as well, but it shows only 100 pF. I guess it is a bit tricky to measure this because it is not just a capacitor. But when I charge the internal capacitor with 3 V and then connect an external 100 megohm resistor, it needs about 72 seconds to discharge to 1 V in the 20 V range, in slow measurement range, which is about 650 nF.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 22, 2017, 11:16:40 am
content: The Fluke 8842 has the option to enable a low pass filter at the input. If the filter is enabled, there is a capacitance of about 660 nF at the input. There is still some 100 K of protection in series. So it depends on the way you measure if you see the capacitance or not.The manual include a schematics for the input.

author: FrankBuss
author_rank: Unknown
timestamp: October 22, 2017, 11:31:25 am
content: Thanks, found it in the manual, section 5-8, Analog Filter. Looks like it is always enabled for slow rate. But it doesn't specify the value, I had to look at the circuit for it at U304. But maybe they expected that customers study the circuit anyway before using the instrument
Short teardown of a Keithley 2500 Dual Photodiode Meter - Page 1
Forum section: electronics / general

author: Echo88
author_rank: Frequent Contributor
timestamp: October 21, 2017, 09:40:50 pm
content: I recently aquired an electrometer, as i needed one to build a high-accuracy voltage buffer for my Fluke 720A KVD. After looking for a fitting electrometer on ebay for a few weeks and missing an ebay-listing for a cheap Keithley 617 by about 5mins, i couldnt be bothered anymore and got myself a Keithley 2500 which nobody was interested in on ebay.Its a Dual Photodiode Meter, essentially it consists of two simultaneous measuring electrometers and two voltage outputs to bias the connectable photodiodes. It has 1 fA-resolution on the lowest 2nA range with 6.5 Digits, 20mA max range, low voltage input burden: 4mV max (since its as feedback type amperemeter), max 100V voltage-output and GPIB-connectivity.Therefore it fits my needs to precisely measure the input bias of the planned KVD-voltage buffer, but of course isnt as good as a Keithley 617 or other top-notch-electrometers.With the triax-input shielded by aluminiumfoil i measured about 90fApp-noise at 10NPLC over about 10h, by averaging these measurements over 20 samples i get about 20fApp-noise.Manual can be found here:https://cdn.testequity.com/documents/pdf/manuals/2500-2502-M.pdfNow to the teardown (finally a device which doesnt already has a teardown-thread on the eevblog-forum):I was expecting to see old clunky rectangular reed-relays and long gigaohm-resistors in a separate metal-shield, instead a LMC6001 and minimal surrounding components do the job pretty well.The LMC6001 is protected by J2611 JFETS connected as low leakage diodes and the whole range-switching on the board is done by a COTO-relay, AQV201A OptoFETs and MAX319 Analog Switches. The feedback-resistor is a 500M 1% resistor.Interesting detail: the slots which isolate the LMC6001 and the triax-input-pin.The first image shows the K2500 while measuring only channel 1 with 6.5 digits, because i was logging the noise-characteristic over GPIB. Normally it shows both input-channels on the display. The front is still a bit dirty and needs to be cleaned.

author: TiN
author_rank: Super Contributor
timestamp: October 21, 2017, 10:42:41 pm
content: Great job, keep it coming. I didn't even see one.It's interesting combo of K2000 platform with dual-line matrix VFD front panel.
PROMO CODES? - Page 1
Forum section: electronics / general

author: itsbiodiversity
author_rank: Regular Contributor
timestamp: October 17, 2017, 03:54:07 pm
content: Is anyone out there aware of any current promotional offers for metrology equipment? Sites such as newark, testequipmentdepot, teequipment.net, etc? Feel free to PM me if the codes cannot be posted in an open forum.
Ohaus Analytical Plus Advice - Page 1
Forum section: electronics / general

author: jnestor481
author_rank: Newbie
timestamp: October 10, 2017, 11:56:33 pm
content: Hello all,Bought a used Ohaus off ebay few months ago. 210 model. Was busy with work and have finally got around to setting it up. Realized that the tray ring was not included. Keep getting an error message after it goes through the self test cycle , "Err 8.2" which in the manual is listed as an internal power error and recommends just restarting the unit. Does not work for me sadly.Is the tray ring essential to have for the tray to work properly, hence the error? When it's doing the self test cycle on startup i have it level , the sides and top of the tray area are covered blocking air pressure changes, and the tray and tray shield are inserted per manual instructions. Hope I'm not making a dumb mistake and missing something obviousNew to these devices, thought I would try here for some insight. Any help much appreciated.

author: wraper
author_rank: Unknown
timestamp: October 11, 2017, 12:17:06 am
content: Ring is not required. Pan is the only thing needed for them to work. Try placing them on stable surface like concrete.

author: wraper
author_rank: Unknown
timestamp: October 11, 2017, 12:48:02 am
content: Quote from: jnestor481 on October 10, 2017, 11:56:33 pmIt does not say anything like that. It says "Power on load out of specification" which usually happens if pan is missing or something is placed on it. Also can happen if balance is put on unstable surface or left with open doors and cannot get a stable reading. To work stable such balances need stable (heavy) surface underneath and no wind blowing around, so any air coolers must be switched off, windows closed.

author: jnestor481
author_rank: Newbie
timestamp: October 11, 2017, 01:44:35 am
content: Sorry you're right. Had the manuals mixed up. Letting it run through the self test cycle again on a sturdier surface. Worried the load cell is damaged. Are these worth getting repaired if so ?

author: wraper
author_rank: Unknown
timestamp: October 11, 2017, 08:15:42 am
content: Quote from: jnestor481 on October 11, 2017, 01:44:35 amI doubt there is a load cell. More likely to be electromagnetic force restoration balances. Such balances may suffer one thin coupling part snapped if high load is applied. Look if pan is lifted up alittle bitwhen you attach power to the balances, I mean physically attaching cable, not by pressing ON button.Like these:

author: wraper
author_rank: Unknown
timestamp: October 11, 2017, 08:48:18 am
content: BTW this might be just a lever where load is put on had been displaced while transporting.