hybridfree/eevblog-posts huggingface dataset:
HP/SYMMETRICOM GPS antennas - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: March 07, 2022, 05:09:22 pm
content: Hello,Can anybody explain the differences between the 2 GPS antennas 58504A (Z3801) and 58532A (58503B). Physical is obvious but for other specifications ? Thank you
Agilent metal work whisker growth (34420a) - Page 1
Forum section: electronics / general

author: lowimpedance
author_rank: Super Contributor
timestamp: June 18, 2021, 01:14:02 am
content: Owners of Agilent and HP branded meters take note:When servicing a 34420a at work I discovered extensive metallic crystal growth on the shield plate covering the display PCA.See pictures, which is the best I could get and that still doesn't show the full extent of the length of the whiskers.Having found that I opened another Agilent 34420 and an earlier HP one and both had the same issue although to a lesser extent on the HP !.Out of interest I also checked the inside of a 34401a and the same growth could be seen on the mains transformer casing.These meters have lived the greater part of their existence in 50% humidity and 21 deg C temps.A couple of years back I posted about an Agilent ARB that was killed by these metallic growths getting into the power supply, driven by the internal fan.I would recommend checking your expensive hobby gear for any 'metallic' issues , if you haven't already !.

author: Greybeard
author_rank: Frequent Contributor
timestamp: August 25, 2021, 08:13:10 pm
content: What type of metal plating is it? Zinc on steel?I've seen such long whiskers (~2-3mm) on electroplated zinc or tin and on sintered silver tracks on ceramic substrate.What can you do to avoid growing of new whiskers?

author: MegaVolt
author_rank: Frequent Contributor
timestamp: August 26, 2021, 07:58:40 am
content: Quote from: Greybeard on August 25, 2021, 08:13:10 pmAdd lead to the alloy. Other methods do not save it. Not even a coat of varnish.

author: bd139
author_rank: Super Contributor
timestamp: August 26, 2021, 08:04:40 am
content: I’ve seen this in a tektronix 7L12 and HP 3478A before. Seems to be tin plated that does it. I brushed them off carefully and cleaned the device out.

author: 2N3055
author_rank: Super Contributor
timestamp: August 26, 2021, 08:22:46 am
content: You can clean it and stick kapton film over it, where distance to danger is small....

author: Ecogeek
author_rank: Contributor
timestamp: March 04, 2022, 10:50:30 pm
content: These whiskers are metal crystalline growth from stressed plating or manufacturing processes and are conductive and fragile, causing intermittent circuit havoc as they break off.One soluiton is to conformal coat the PCB to prevent any raining conductors from doing any damage. It does seem it takes time for the crystals to grow so wiping down regularly is also a solution.Cheers

author: martinr33
author_rank: Frequent Contributor
timestamp: March 05, 2022, 04:07:41 am
content: More than you ever wanted to know:https://nepp.nasa.gov/whisker/

author: Mickle T.
author_rank: Frequent Contributor
timestamp: March 05, 2022, 06:28:56 am
content: Whisker hell inside a 0.1 ppm INL voltage source
For the Time-Nuts - Page 1
Forum section: electronics / general

author: FransW
author_rank: Frequent Contributor
timestamp: March 02, 2022, 04:15:54 pm
content: From an article in "Nature":Resolving the gravitational redshift across a millimetre-scale atomic sample.https://www.nist.gov/blogs/taking-measure/keeping-time-nistQuote:Our result is enabled by improving the fractional frequency measurement uncertainty by more than a factor of 10, now reaching 7.6 × 10−21. This heralds a new regime of clock operation necessitating intra-sample corrections for gravitational perturbations.UnquoteSeems to be a non-DIY type of clock.Frans
ADuC845 with ADR421 eval board ADC noise - Page 1
Forum section: electronics / general

author: iMo
author_rank: Super Contributor
timestamp: February 28, 2022, 07:48:23 pm
content: FYI - I found a vintage ADuC845 SD eval board in my junkbox.. 24bit SD (with 8052 mcu) + ADR421 2.5V Xfet Vref on the board. Fired it up with powered with a 9V battery and with FT usb dongle for Rx/Tx. The AD's WASP tool was used for "ADC analysis" - the results (2000 samples) - see below..
AN/PDR-56E Radiation meter schematic - Page 1
Forum section: electronics / general

author: jonpaul
author_rank: Super Contributor
timestamp: February 23, 2022, 10:50:53 am
content: Bonjour a tous:Just unearthed US Navy/Air Force radiation survey meter, was $20 at a garage sale, 30 yrs ago.Uses -950V HV, 1P21/931 PM tube scintillatorand ZnS screen /lucite light pipes / mylar membrane to detect Alpha 3 MV from Pu contamination in nuclear carrying vessels, subs and planes.Excellent condition except 5 cond coiled cable meter to surface probe was SO/SJ rubber insulated and frayed at the 6 pin Cannon connectors.worked a bit but no indications, just constant ticks at ~ few Hz, indicating HV leakage.It soon died, SO/SJ rubber cable, -950V PM shorted to PM tube in probe end emitter follower output. Now PSU still has HV and inverter but LV 3.9V and -9V dead.Many variants A..F existed, we have 56E.PROBLEM: ONLY schematic on the web is 56F. Entirely different PCBs, mine has two boards connected by edge connectors, the 56F is single PCB.Seeking any info on these, especially the main meter and PM head schematic and PCB for AN/PDR-56E. Circa 1974.REFS:http://www.diyphysics.com/wp-content/uploads/2012/02/anpdr56f-description.pdfhttps://www.orau.org/health-physics-museum/collection/radiac/survey-meters/anpdr-56.htmlMany thanks ! Mille Mercis!Jon
Lady Heather Samsung UCCM - Page 1
Forum section: electronics / general

author: glosair
author_rank: Newbie
timestamp: February 20, 2022, 02:43:55 pm
content: Assembeling my Samsung UCCM into a case and want to use a Pi3 to run Lady Heather.Is the linux code still suported as I'm getting no data displayed, the coms work (putty can see the data via the a USB adapter) and Lady Heather detects a UCCM but just blank.Is the Linux code still supported?

author: thinkfat
author_rank: Unknown
timestamp: February 20, 2022, 04:13:35 pm
content: Check out the manual. As I rememeber there's a special configuration switch for Samsung UCCM devices.

author: glosair
author_rank: Newbie
timestamp: February 21, 2022, 02:32:55 pm
content: Found the solution in another's posthttp://gotroot.ca/misc/heatherx11_beta_6.14.zipsolved it all.
Using zener references at higher currents - Page 1
Forum section: electronics / general

author: julian1
author_rank: Frequent Contributor
timestamp: March 06, 2022, 10:59:11 pm
content: Consider a zener reference circuit (like a lm399) based on an op-amp, with current-limit resistor + zener at the non-inverting input, and a resistor divider at the inverting input.The zener is 6.25V with a TC zero at 25mA.For higher current, self-heating of the current-limit resistor must be controlled. For example a 10R at 25mA, will drop 250mV and generate 6mW of heat which seems reasonable. (compare ltz1000. 0.7V/120R=5.8mA P=4mW ).The op has typical non-inverting gain of 1 + Rf/Rg. So the main divider must now be (1 + 1k/25k) * 6.25V for a 6.5V op output.What is the effect of a 1k/25k asymetrical divider ratio? It looks unusual. I suspect it will amplify the TC of the current-limit resistor, but only slightly?An alternative approach might be a high-side instrumentation amplifier with gain, but I am not sure if that is necessary.

author: tszaboo
author_rank: Super Contributor
timestamp: March 06, 2022, 11:29:31 pm
content: Just run it at the well defined currents. If you need more current, buffer it with a precision opamp, and add a BJT on the output of the opamp.

author: julian1
author_rank: Frequent Contributor
timestamp: March 06, 2022, 11:36:54 pm
content: Quote from: tszaboo on March 06, 2022, 11:29:31 pmThat's all in place. Currently dropping 5V across 200R @ 25mA. which is 125mW of heat. I think that's way too much, even for z-foil.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 07, 2022, 08:46:33 am
content: The resistor (R_d) value for the driving current has no direct effect on how much the resistor TC is effective. The relevant combination is R_g/R_f*R_d.A very small resistance, small voltage results in more effect of the OPs offset / dirft on the current.An instrumentation amplifier would not really help.There is no real need to drop 5 V there, some 0.5 to 1 V should be enough. Having a gain of 1.5 may be conveninet to get close to 10 V at the amplifier output. A gain of 1.1 may be an option, as there are ready made arrays for 1:10.
3457A Switching Noise on Measurement bus. - Page 1
Forum section: electronics / general

author: TaylorD93
author_rank: Regular Contributor
timestamp: February 15, 2022, 06:15:43 am
content: Hi folks,Just wondering if im being an idiot with my DMM. I was gifted a HP 3457A by my mentor when he retired. Its not been calibrated since about 2006.I have been repairing a WEIR 4000T Linear PSU, and i had the DMM connected to its output terminals, while also having my Scope connected measuring output Ripple.While the DMM was connected, i was detecting some odd switching noise on the PSU output on the scope, I thought it may have been noise coupled on the DMM leads as its a HiZ input, however disconnecting the DMM leads at the DMM (still connected at the PSU end) the switching noise disappeared. This leads me to believe its coupled in by the DMM.Surely a DMM of this quality shouldnt be passing switching noise onto its measurement terminals? Am i missing something?

author: Kleinstein
author_rank: Super Contributor
timestamp: February 15, 2022, 08:46:17 am
content: In the AZ mode the DMM will cause some switching spike at the input. This can be quite noticable to a sensitive source - though a linear power supply of the usual power level should be OK with this.The injected current can come from the switching of the input in the auto zero cycle. In the 3457 there are quite some series resistors for protection, so the spikes should not be that large. The 3457 DMM also has an extra precharge phase to reduce the switching spikes, but this may still be not perfect and there are some reports on defects in the precharge circuit. Such a defect would cause higher than normal switching spikes and likely also more input bias current. In more normal use such a defect may be essentially unnoticed.

author: KT88
author_rank: Frequent Contributor
timestamp: February 15, 2022, 09:22:09 am
content: There is a chance that the noise is coupled magnetically into the test leads. Have you tried to to move them around or make a poor mans twisted pair out of it?

author: TaylorD93
author_rank: Regular Contributor
timestamp: February 15, 2022, 12:55:20 pm
content: No not yet, I will try that.I will also adjust the NPLC and see if that changes the frequency of the noise, if it does then its highly likely it is what Kleinstein suggestedthanks
LM399 circuits from the datasheet, which one is better? - Page 1
Forum section: electronics / general

author: dmmguy
author_rank: Contributor
timestamp: February 06, 2022, 04:09:11 pm
content: Hi everyone,Both taken from the LM399 datasheet; which one is better?Thanks

author: KT88
author_rank: Frequent Contributor
timestamp: February 06, 2022, 05:48:46 pm
content: A salways: It depends...The right one is optimized for portable (battery operated) use at the cost of higher noise (lower Iz) and drift (it takes some time for the heater to settle).

author: branadic
author_rank: Super Contributor
timestamp: February 06, 2022, 06:28:41 pm
content: I would say: "None of them, use the bootstrapped solution instead."-branadic-

author: Gyro
author_rank: Super Contributor
timestamp: February 06, 2022, 06:57:25 pm
content: That would be the second one then wouldn't it? The 200k resistor is just there to make sure it starts up.

author: dietert1
author_rank: Super Contributor
timestamp: February 06, 2022, 07:01:01 pm
content: Yes, the circuit shown in the lower rightisthe usual bootstrap circuit. The 200k resistor is for startup and the zener current comes in from the output via the 5k resistor. A standard value for that resistor would be rather 3 KOhm to pass about 1 mA from 10 V to 7 V.Regards, Dieter

author: Andreas
author_rank: Super Contributor
timestamp: February 06, 2022, 07:16:45 pm
content: Quote from: Gyro on February 06, 2022, 06:57:25 pmThats right. (but the 5K resistor should be more in the 3K range to get the specified 1mA current through the LM399)For real precision cirquit I would improve the trimming scheme (like on other precision references like the AD587).A pot with rather high T.C. should not be in series with usually better precision resistors.And also the heater voltage should be stabilized for maximum stability if ppm level is needed.With best regardsAndreas

author: bdunham7
author_rank: Super Contributor
timestamp: February 06, 2022, 07:19:54 pm
content: Quote from: Andreas on February 06, 2022, 07:16:45 pmI've always been curious--is something like an LM7815 considered good enough for all purposes or is it ever worthwhile to use the 10V output with a comparator setup to stabilizer the heater input even more?

author: Andreas
author_rank: Super Contributor
timestamp: February 06, 2022, 09:08:59 pm
content: Some results are in the LM399 thread.e.g. herehttps://www.eevblog.com/forum/metrology/lm399-based-10-v-reference/msg443181/#msg443181so you can decide by yourself for some ppm/V how much stabilisation is needed for your applicationwith best regardsAndreas
Fluke 7526A Precision Process Calibrator Teardown - Page 1
Forum section: electronics / general

author: Echo88
author_rank: Frequent Contributor
timestamp: February 18, 2022, 08:36:55 pm
content: I had the opportunity to open up a Fluke 7526A Precision Process Calibrator, basically the bigger and more recent brother of the Fluke 525B.The older 525B was designed by Martell Electronics (named M2001) and rebadged by Fluke, i assume they did the same with the 7526A (named M3001, although the 7526A-pcb only states "Fluke 2017").I found xDevs has already done a 525B-teardown and after comparing the mainboard-pictures with the 7526A its evidently very similar with a few more precision resistors, better voltage reference (LM399H compared to VRE302) and added frontpanel-pcb.Boggles the mind to see that they redesigned the pcb, but are still incapable of installing the correct RS232-connector, still using three wires and a ziptie...thats what you get for about 10k$ new.Oh and the Voltage Output is not capable of producing a bipolar voltage with the 7526A "All outputs are positive only, unless otherwise noted."So here follows a short teardown with pictures and a list of the used ICs/components.Used parts:1x National Instruments TNT4882 GPIB-Communication1x LT1281 RS232 Communication1x ATMega128 Controller1x BPSX 2-08-00 BIAS 2 Watt Power Supply1x LM399H (with a LM317 next to it)4x LTC1151CSW Zero Drift OP1x AD8629 Dual Zero Drift RRIO OP2x LTC2051HV Dual Zero Drift OP2x MAX333ACWP Quad SPDT Analog Switch1x DG408DY 8-Channel Analog Switch1x LT1595A 16Bit Serial Multiplying DAC1x LT1595B 16Bit Serial Multiplying DAC1x CS5534-BSZ 24Bit-ADC with PGA1x PS-2801-4 Quad Photocoupler3x 74HC595 Shift Register4x H11L1 Schmitt Trigger OptocouplerPrecision Resistors, each:15k18.2k25k10k2.5k25k2.5keach marked: AE YF1x 10R Z201TResistor Networks blue, marked AE:4Pins each002B9K000002B75k00002B120K0Transformer Secondary:7.3V18.2V17.3V96.6VRelays: ea2-5tnuSmall Front PCB:1x LT1373 DCDC-Switcher1x LTC2410 24Bit ADC1x LTC2051HV1x Caddock Network3x Precision Resistors1x ADR421 Voltage Reference3x Relay ea2-5tnu3x H11L1 Schmitt Trigger Optocouplerhttps://xdevs.com/fix/f525a/https://eu.flukecal.com/products/obsolete-products/525b-temperature-pressure-calibrator?quicktabs_product_details=2http://www.calibratordepot.com/browseproducts/Martel-M2001-Benchtop-Multifunction-Calibrator.htmlhttps://eu.flukecal.com/products/electrical-calibration/electrical-calibrators/7526a-precision-process-calibratorhttps://www.instrumentation2000.com/martel-3001.html

author: Echo88
author_rank: Frequent Contributor
timestamp: February 18, 2022, 08:40:35 pm
content: More pictures due to post size restrictions.

author: Echo88
author_rank: Frequent Contributor
timestamp: February 18, 2022, 08:41:41 pm
content: Done.
Fiber optic temperature measurements. - Page 1
Forum section: electronics / general

author: geggi1
author_rank: Frequent Contributor
timestamp: February 03, 2022, 02:32:05 pm
content: Hi!I got a new project for a client measuring the temperatur inside a subsea umbelical.The test is to measure the temperature during diffrent configurations of load and layers on a cable reel.All the load on the cable is more or less under controll. I got the main parts figgured out, but not the temperature measurement.Can anybody give me some reccomandations for test gear measuring the temperature through the internal fibre optics in the cable?I have not yet got any info about if its SM or MM fibre, but normally our client are using SM fibre.

author: nfmax
author_rank: Super Contributor
timestamp: February 03, 2022, 02:59:46 pm
content: It sounds like you are looking for a fibre optic DTS? Before I (semi) retired, I spent 20 years or so working in this field, mostly in the oil & gas industry, including SURF applications. I'm not involved now, but I do still have contacts. Please PM me!

author: geggi1
author_rank: Frequent Contributor
timestamp: February 03, 2022, 08:45:58 pm
content: I will contact you on monday or tuesday when im back at the office.Doing an early weekend this week.

author: nctnico
author_rank: Super Contributor
timestamp: February 04, 2022, 12:18:49 am
content: Contact these guys:https://optics11.com/

author: Electrole
author_rank: Contributor
timestamp: February 04, 2022, 02:50:33 pm
content: Also, check out this company:https://shute.dk/(No affiliation, BTW)
Optical Detector and Optical Power Meter - Page 1
Forum section: electronics / general

author: warped314
author_rank: Newbie
timestamp: January 27, 2022, 10:51:13 pm
content: Hello All,First post here. I'm a technical specialist working for Ball Aerospace out of Boulder, CO. We're looking for an ISO 17025 accredited, or Z540.1 accredited, or Z540.3 accredited calibration service provider who can either calibrate onsite or guarantee a 24hr turnaround time for a Newport Optical Detector 818-IG and Newport Optical Power Meter 1936-R. So far, no luck with Trescal, Transcat, Tektronix.Anyone know a company which does onsite calibrations for these? I don't even know what this would be used for, it's all new stuff to me...https://www.newport.com/p/1936-Rhttps://www.newport.com/p/818-IG--DB

author: veedub565
author_rank: Frequent Contributor
timestamp: January 28, 2022, 11:11:44 am
content: You could try Keysight, although I'm not sure if they do 3rd party products over there like they do in Europe.

author: LaserEng
author_rank: Regular Contributor
timestamp: January 28, 2022, 05:04:18 pm
content: I think you may struggle to find what you are after, a lot of the optical stuff can only be calibrated with the OEM manufacturer. I work with laser power meters, mostly made by Ophir which is a subsidiary of Newport, and the company I work for has thousands of the power meters by Ophir and the only place we have been able to get them calibrated is by Ophir themselves as they design in a proprietary calibration procedure, though thats not to say someone could emit a known power light source at the device and record the reading.If turnaround time at Ophir is anything like the rest of Newport then you are likely looking at weeks or months for turnaround time. Also their calibration is questionable, for example we use 400W laser power meter detectors and Ophir calibrate them at 1 point in each wavelength setting and usually that is in the mW or A few Watts range which is basically almost down in the noise.

author: jonpaul
author_rank: Super Contributor
timestamp: January 31, 2022, 12:00:56 pm
content: Bonjour Only Newport can do this.Suggest to contact their engineering and tech support.Doubt if onsite is possible as special fixtures and equipment are needed.Plan to ship the equipment to Newport via Fed Ex, etc.If in warranty or CAL period the work may be no charge.Kind Regards,Jon

author: Henrik_V
author_rank: Regular Contributor
timestamp: February 02, 2022, 10:22:44 am
content: I doubt that there is a lab that offers certified on site calibration for these meters.If turn around time is such a problem just buy a second onealso nice for cross checking (migth need a third one to know which one drifted)Labs that offer such services can be found (or requested) at the national accreditation bodies.. (and of course the national metrological labs, which usually offer the lowest uncertainties (for the highest prices ) but often are not listed in the dadabases.For a calibration it 'just' needs a known source *... however a justification nowadays mostly needs the manufactor...* and a procedure and a MUB and ...
Has anyone seen a mechanical chopper Keithley 147/148 inside? - Page 1
Forum section: electronics / general

author: MegaVolt
author_rank: Frequent Contributor
timestamp: January 26, 2022, 09:51:59 am
content: Maybe there are some photos? Or does someone have a non-working block to disassemble it?

author: branadic
author_rank: Super Contributor
timestamp: January 26, 2022, 02:38:08 pm
content: I wouldn't expect that much of a difference to the picture shown here:-branadic-

author: branadic
author_rank: Super Contributor
timestamp: January 26, 2022, 06:03:07 pm
content: Curious, I've searched a bit, but couldn't find a mechanical chopper based on piezo beams, while reed relays have at least been considered.https://patents.google.com/patent/US3320559A/enhttps://www.eeeguide.com/chopper-type-dc-amplifier-transformer/-branadic-

author: inse
author_rank: Super Contributor
timestamp: January 26, 2022, 06:46:51 pm
content: A time ago I had a HP 425A Microvoltmeter from the late 60‘s, it had a electro-optic chopper.A motor with a segmented disc rotating between a lightbulb and photoresistors.Well sealed, there was not much to see from the outside, unfortunately.

author: branadic
author_rank: Super Contributor
timestamp: January 27, 2022, 05:48:06 am
content: Fortunately doktor pyta took his broken chopper apart and took some pictures last night.https://www.eevblog.com/forum/repair/keithley-148-nanovoltmeter-repair/msg3969494/#msg3969494-branadic-

author: Vtile
author_rank: Super Contributor
timestamp: February 01, 2022, 09:30:21 pm
content: Pretty much all these choppers mentioned here in various threads were a standard field instrumentation devices in a industrial (& scientific naturally) instrumentation toolbox back in the 60's and 70's. Modulated and demodulated autozeroing DC measurements from distant field sensors to analog computers, before digital fieldbuses. That is what I have read (not nearly as wide to be satisfied), handbooks of instrumemtation of that era might be satisfying to skim through to people who are interested these devices, maybe.
Question: Regarding Height Gauges - Page 1
Forum section: electronics / general

author: troked17
author_rank: Newbie
timestamp: February 01, 2022, 02:40:39 pm
content: This may be a silly question to some but I'm looking at height gauges and wondering what the maximum height could be measured?For example, the Moore & Wright MW192-20Dheight gaugesize is 150mm but what does it measure when you take into account the base and the digital unit?Thanks.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 01, 2022, 05:00:25 pm
content: I'd think any height gage is listed by the maximum measurement. The actual height of the unit will be more. IMO, the maximum useful height is limited by how stable the unit is. You can't measure if it's trying to tip. Adding an indicator solves that. I have a Starrett that's way higher than is reasonable for the small base.

author: mendip_discovery
author_rank: Super Contributor
timestamp: February 01, 2022, 05:38:44 pm
content: Get one with replaceable attachments then you can at least add things to it to do what you want to do, either a clock or a modified anvil.Mechanical Measuring tools much like Electrical measurement has its Brands, Linear/Unbranded are your £2.99 meters, Moore and Wright are your amprobes, Mitutoyo is akin to Fluke, if you want 8.5digit sadness then look up Tesa Microhite stuff, or even SIP205M.Typically they will measure 150mm plus a little extra. It will take into account the size of the head.I suggest looking for a little granite surface plate as well, its a very good surface to measure on.
YOKOGAWA WT1600 Power meter calibration mode - Page 1
Forum section: electronics / general

author: pasta2018
author_rank: Regular Contributor
timestamp: January 03, 2022, 12:04:58 am
content: Hi, I 've got a wt1600 repaired, changed the sample resistance in the sample board, now I test It and find the error is out of tolerance. I have got Fluke calibrator, but I don't know how to get in the calibration mode of wt1600, can some one provide a service manual of tell me how to get in the calibration mode, many thanks.

author: pasta2018
author_rank: Regular Contributor
timestamp: January 03, 2022, 09:17:00 pm
content: there is a adjustment procedure for wt230, maybe I can try this method.

author: pasta2018
author_rank: Regular Contributor
timestamp: January 07, 2022, 02:21:40 am
content: That doesn't work on a wt1600, any other suggestions？

author: PE1RQF
author_rank: Newbie
timestamp: January 14, 2022, 03:09:22 pm
content: Hi,Try switch on instrument while pressing display button. After start up, press shift and than display button.Regards,Erik

author: pasta2018
author_rank: Regular Contributor
timestamp: January 26, 2022, 06:44:57 am
content: It's really great, that works. Really thanks.I will try to calibrate it.

author: pasta2018
author_rank: Regular Contributor
timestamp: January 26, 2022, 08:45:13 am
content: you are supper great.

author: PE1RQF
author_rank: Newbie
timestamp: January 26, 2022, 05:53:22 pm
content: Fine that it is workingregards,Erik

author: pasta2018
author_rank: Regular Contributor
timestamp: January 27, 2022, 06:28:23 am
content: One more thing I 'm not quite sure. There are 100V(500) 100V(5.5k) 1A(500) 1A(5.5k), does 500 5.5k means the frequence of the standard voltage or current, and for the other values, apply DC signal would be ok?

author: dl1640
author_rank: Regular Contributor
timestamp: January 27, 2022, 12:11:39 pm
content: Apply rated signal at 60Hz

author: pasta2018
author_rank: Regular Contributor
timestamp: January 30, 2022, 02:20:17 pm
content: Thanks, I will try that and report then.

author: PE1RQF
author_rank: Newbie
timestamp: January 30, 2022, 02:53:01 pm
content: Apply rated signal at 60Hz is correct. it is the filter adjustment.

author: pasta2018
author_rank: Regular Contributor
timestamp: February 03, 2022, 03:08:26 pm
content: now I'm a little confused. As in the picture I uploaded, for10V,apply 10V 60Hz15V, apply 15V 60Hz30V,apply 30V 60Hz60V apply 60V 60Hz100V apply 100V 60Hz150V apply 150V 60Hz100V(500) apply 100V 500Hz100V (5.5k) apply 100V 5.5kHzAre these right?

author: dl1640
author_rank: Regular Contributor
timestamp: February 04, 2022, 12:38:08 pm
content: That's correct.(500Hz), (5.5kHz) for measurement under LPF set to ON.The reference signal applied is at commercial frequency 60Hz/50Hz will be fine.

author: pasta2018
author_rank: Regular Contributor
timestamp: February 04, 2022, 01:55:20 pm
content: ok, I got it. Thanks very much.
xo aging after the time frames in datasheet - Page 1
Forum section: electronics / general

author: metebalci
author_rank: Frequent Contributor
timestamp: February 15, 2022, 04:51:56 pm
content: I have a device with an ocxo inside. Aging spec is 50ppb in 1 (first) year, 25ppb in 2 years. After 2 years, lets say 5, what would be the aging ? How is this estimated ?

author: mendip_discovery
author_rank: Super Contributor
timestamp: February 15, 2022, 06:23:00 pm
content: Year 1 +(Year 2 x 4) would be my guess.The first year is when you see the most drive then after that it is what year 2 is for each year. If it's been adjusted then year 2 would be would be the expected annual drift from there on.

author: metebalci
author_rank: Frequent Contributor
timestamp: February 15, 2022, 10:13:55 pm
content: My understanding is it is not linear and getting more and more stable. So I expect it to be close to 2 years number even for 5 years (at least better than 4x). But I dont understand if there is a way to roughly estimate this, if there is an approx. model or it is just impossible. I think they normally test this by speeding up the aging, but I dont know why they particularly stop at 2 years for example. For the numbers they measure I saw there are simple models (eg what happens at 6 months), but what to do if there is no number lets say for 5 or 10 years.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: February 16, 2022, 08:34:31 am
content: I have encountered the need to predict the aging of an alternator after a long period of time. The company that sold us the generators agreed to give a guarantee for a long time. To do this, they measured the aging for 1 month and approximated it with a logarithmic function. And they gave us only those generators that remained in tolerance for the time we needed. Of course, there are still random events that cannot be so predicted. But this is the best they could do for us.

author: metebalci
author_rank: Frequent Contributor
timestamp: February 16, 2022, 12:26:20 pm
content: OK I understand. It seems that is the best that can be done. I find this paper quite helpful:https://www.isotemp.com/wp-content/uploads/2011/04/Crystal-Oscillator-Aging.pdfI made a simple calculation like in the paper above, for an Rb clock, last calibration ~16 years ago. It has 0.5ppb/year after 2nd year. If I do it right, it makes ~12 mHz change after 16 years. I see 6 mHz in measurement against a GPSDO.
DMTD Beware Counter ADEV when measuring phase - Page 1
Forum section: electronics / general

author: jpb
author_rank: Super Contributor
timestamp: January 29, 2022, 01:15:20 pm
content: I've just got round to writing code to properly measure the output of my DMTD system and was puzzled (and somewhat disappointed) to find that the manually measured ADEV (of approximately 200 nsecs equivalent to 2 x 10-12at 0.1 secs) was coming out at ~3.5 to 3.9 x 10^-12when I fed the data into STABLE32!Having dug around in the manuals and done a bit of thinking I worked out the solution - the Counter (FCA3100) ADEV is only valid for frequency measurements not time measurements.The counter uses the formula (ignoring the divide by 2 * (N-1))sqrt(Sum (xi+1-xi)2)STABLE32 uses the correct formulasqrt(Sum ((xi+1-xi) - (xi-xi-1))2)orsqrt(Sum(xi+1- 2*xi+ xi-1)2)Assuming the noise is IID and that we sum enough terms that any cross-correlation goes to zero (zero mean) with a sd of sigma for the xi2type terms then we only need to consider these square terms.The counter formula amounts toADEV = sqrt(sigma2+ sigma2) = sqrt(2) * sigmawhile the STABLE32 formula comes toADEV = sqrt(sigma2+ 22*sigma2+ sigma2) = sqrt(6)*sigmaand the ratio is sqrt(6/2) = sqrt(3) = 1.7 (roughly)and this is what I was observing (approximately in my practical measurements.So beware of just taking the ADEV output of the counter at face value - it will be too optimistic for time measurements.
soldering eureka wire - Page 1
Forum section: electronics / general

author: m3vuv
author_rank: Super Contributor
timestamp: January 01, 2022, 02:00:01 pm
content: Hi all,ive an old avometer model8 mk1,It has a wrecked bottom resistance board,one resistor is wirewound with 120 turns of eureka wire approx 980 ohms,this needs replacing,i have the wire,its silk covered but any idea how to solder this as its 44swg,cant see how to remove the silk to solder it without destroying the wire,can anyone tell me the best way to do it?,tia.

author: jpanhalt
author_rank: Super Contributor
timestamp: January 01, 2022, 02:18:02 pm
content: For very fine wire, I use a molten salt bath. NaOH or KOH (or a mixture) melts at a fairly low temp. Adding a little NaNO3 can help. My bath is just a steel block with a hole for the lye and a second hole for a thermometer/thermocouple.I did some studies of various mixtures (portion of Table attached) years ago. Silk is basically a protein and should come off very easily compared to the non-solderable magnet wire enamel that I studied. If you are careful, you can avoid the darkening. In any event, what comes out is solderable with typical Kester 44 flux.You can also try a soft flame.

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: January 01, 2022, 05:33:57 pm
content: Quote from: m3vuv on January 01, 2022, 02:00:01 pmWhat is "eureka wire"?Why not simply replace the resistor with an equivalent, modern, WW or metal foil?(Do we need atest equipment for masochistssubsection in eevblog??)

author: jpanhalt
author_rank: Super Contributor
timestamp: January 01, 2022, 06:26:00 pm
content: At first, I thought maybe it was such fine gauge wire that when you soldered it, you yelled, "eureka." Then, I looked it up:https://en.wikipedia.org/wiki/Constantan

author: Vtile
author_rank: Super Contributor
timestamp: January 02, 2022, 10:57:34 pm
content: Does the blob of solder at the tip of iron trick work with silk as it works with coil/enamel wire. So the technique is to melt a blob of solder to hot 300+deg.C iron and then poke the wire through the blob, so the exposed end will take the solder and with help of heat kind of burn and wrap the coating away.I assume that you have proper bakelite resistance bridge to verify the resistance (and not these digital nonsence with excessive display numbers), plus a bunsen burner heated soldering iron!

author: m3vuv
author_rank: Super Contributor
timestamp: January 19, 2022, 01:14:40 pm
content: Didnt bother in the end,brought another avometer model 8 mk 1 cheap for speares,the aim was to swap the lower resistance board,but after inspection ,it turns out the only fault was the cutout was out of adjustment,after adjusting it as per manual the meter works fine and reads to spec so didnt bother,just kept the original for the meter movement as a spare,also do these read peak to peak or rms?

author: Gyro
author_rank: Super Contributor
timestamp: January 19, 2022, 05:43:49 pm
content: Neither. They are average responding, calibrated to read correctly (RMS equivalent) on a sine wave. Reading on other wave-shapes (duty cycles) will vary.
СО 3001. New russian Ommeter 7.5 digits. - Page 1
Forum section: electronics / general

author: MegaVolt
author_rank: Frequent Contributor
timestamp: January 20, 2022, 09:26:23 am
content: Name "СО 3001" (сaution: russian letters).http://www.znp.ru/prod/co3001.htm

author: MegaVolt
author_rank: Frequent Contributor
timestamp: January 20, 2022, 10:58:30 am
content: Price.1$ = 75р

author: ch_scr
author_rank: Frequent Contributor
timestamp: January 20, 2022, 12:45:57 pm
content: I have translated the picture into english,mostly.Edit: Updated from Information below

author: MegaVolt
author_rank: Frequent Contributor
timestamp: January 20, 2022, 12:55:40 pm
content: ГСТ = Stable current generator.ПСН = Resistance converter to voltage.ОП = Reference.Ш = Shunt.Устройство ввода вывода информации = IO Interface.МОм = MOhm

author: Vgkid
author_rank: Super Contributor
timestamp: January 21, 2022, 08:11:48 am
content: Thanks for posting this. ZNP appears to make some pretty nice products, I spent some time browsing the website.
Calibration cost for Datron 1281 in Ontario? - Page 1
Forum section: electronics / general

author: Jester
author_rank: Frequent Contributor
timestamp: January 01, 2022, 06:09:44 pm
content: For anyone with a Datron 1281 that has it calibrated in Ottawa or Toronto, what have you had to pay for a calibration?What about 3458A calibration cost?

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: January 05, 2022, 09:33:47 pm
content: Most calibration equipment cannot be calibrated in Canada unless you work for a national laboratory. Instruments will likely be shipped to an American calibration centre such as the one in Texas (Transcat).Recent prices for a Datron 1281 calibration is somewhere around 2300 CAD to manually calibrate each range with data. A 3458A or a 6581T will cost about 1300 CAD to calibrate based on a resistance and voltage standard with data.Good luck.
HP 3458A A2 Board Revision E Changes and Issues - Page 1
Forum section: electronics / general

author: tonyz663
author_rank: Newbie
timestamp: January 03, 2022, 07:56:24 pm
content: I am currently working on an issue with my 3458A A2 board (Rev A). I have the CLIP and it has up to Rev D in changes, which I already incorporated. I noticed that there was a component added in series with 100 ohm resistor R006 (appears to be a diode with number 1902-0956?) from reviewing photos of Rev E boards. Does anyone have a Rev E or later schematic diagram for the A2 board to confirm any changes? Let me know your thoughts.My current problem with the A2 board revolves around the SCAL 1 and 0.1 calibration functions. I was recording voltages at both frequencies and get a steady ac voltage reading from the 3458A at 100 kHz and get a slow voltage decrement at 8 MHz for both 1V and 0.1V rms. The 3V rms voltages seem to be consistent and no drift downs with frequency changes. I am using a 3325A that was calibrated around 2016 and does not drift down with other meters. Are there any thoughts on areas to check from past experiences?
GenRad 1863/4 Megohmeters - Page 1
Forum section: electronics / general

author: jonpaul
author_rank: Super Contributor
timestamp: January 17, 2022, 08:50:18 pm
content: Bonjour a tous,Does anyone have these, looking for meter movement, knobs and cases, have several that could be fixed but need to find a junker or parts.One is 1863, works fine but case has usual split corners. Refugee from Lawrence Livermore Labs (LLNL) salvage lot, 1980s, all electronics was $0.30/#!Also located original manual...The 1864 has a broken PCB and dead meter movement. Special scale and oval GenRad type.Will add photos later.PM me if anyone can assist!Mille merciesJon
How to clean test & measurements equipment. - Page 1
Forum section: electronics / general

author: miro123
author_rank: Frequent Contributor
timestamp: December 18, 2021, 09:13:43 pm
content: The general rule is to take care for the precision T&M equipment.The reality is we buy 30..35 years old HP3458 which has run 24/7 in heavy industrial environment.I have some HP3456s and they are not looking great inside.Mostly manufacture provides procedure for maintaining and cleaning, but I cannont find such document for HP3456s. To make thinks more complex the two HP3456s are both EU version but with diffrent desing - one is fanless another with forces cooling from behind.My question is how can I mention those old HP3456s?It is needless to say that those old equipment is already botched to some degree - e.g. re-caped PSU with flux residue is rather common than exception.Thanks in advanceMiro

author: alm
author_rank: Super Contributor
timestamp: December 18, 2021, 10:50:44 pm
content: I would not clean the analog PCBs with any liquids in fear of spreading contaminants to the high-impedance areas. I would try to stick to blowing clean air from e.g. a compressed air can or a suitable compressor that does not have oil in the output.The panels etc with electronics removed you can clean with mild soap and warm water. Seethis stickyin the repair section, especially the threads by robrenz, likehis HP 6114A restoration.As for the PCBs, unless your meters are having issues that appear related to excessive leakage, or you see corrosive substances like leaked caps, I would leave them alone. You are more likely to degrade performance or damage them than improve anything. If I had to work on the analog PCB, but not on the high-impedance part, I'd try to clean the board without getting any fluids on the high-impedance parts. If I had to work on the high-impedance parts, I'd clean the board with multiple rinses of fresh IPA and possibly a final rinse with methanol (I believe that's suggested for Keithley electrometers).My experience is that many fanless devices look almost spotless inside. Especially since these DMMs were often used in electronics labs and even clean rooms. But I guess it depends on where the unit came from.

author: Squarewave
author_rank: Frequent Contributor
timestamp: December 23, 2021, 04:24:36 pm
content: I would think something like a 3458 would have been on the bench a clean lab rather than a heavy industrial environment.

author: miro123
author_rank: Frequent Contributor
timestamp: December 23, 2021, 07:38:28 pm
content: Quote from: Squarewave on December 23, 2021, 04:24:36 pmIt seems to be completely opposite to what most people think. Look at link below - interesting part starts at 13min:0secJohn Kenny from Keysight explains why HP3458 is used primary in mass production facilities.
change the 12V GPS antenna port to 3.3V, symmetricom truetime timevault - Page 1
Forum section: electronics / general

author: testpoint1
author_rank: Frequent Contributor
timestamp: December 19, 2021, 06:48:04 pm
content: I got a symmetricom truetime timevault, it used a 12V GPS antenna, the antenna is quite old and expensive, just change the circuit to 3.3V, add a NCP1117 and a capacitor (10uF), very easy.disconnect the 12V (one end of L7), add the NCP1117 (3.3V) and output capacitor, now you have the 3.3V GPS port, the 3.3V GPS only 10-20 USD, the 12V GPS may need 400 USD, you just use 0.1 USD and 10 minute save 400 USD. forget the 12V GPS antenna, let it be.I also have a problem, how to reset the password of the "truetime timevault", I try to connect it by RS-232 port, but "login refused", check the manual, seems need to into the "bootloader mode", but how to do? thank you.

author: testpoint1
author_rank: Frequent Contributor
timestamp: December 19, 2021, 06:54:40 pm
content: and you can change it to 5V, just use another NCP1117ST50 instead of NCP1117ST33.

author: testpoint1
author_rank: Frequent Contributor
timestamp: December 22, 2021, 02:50:17 pm
content: can not "bootloader mode" now, but the problem faced new, that is the famous 1024 weeks rollover problem, seems no workaround now.
Fluke Series 2 vs series 3 - Page 1
Forum section: electronics / general

author: Bwarb
author_rank: Newbie
timestamp: December 19, 2021, 05:50:03 pm
content: GreetingsCan anyone tell me what the difference is between a Fluke Series 3 and series 2 meter is.I can find a service manual for Series 2 but not series 3Thanks for any info

author: mendip_discovery
author_rank: Super Contributor
timestamp: December 19, 2021, 06:38:07 pm
content: Which model?

author: Shock
author_rank: Super Contributor
timestamp: December 20, 2021, 01:31:34 am
content: Search for the model with roman numerals in google. Fluke 73 III manual (for example).Typically if they both look the same it's only going to be minor changes but Fluke updates the series to also include new safety features and often revises the pcbs. So generally it's better to go with the latest series you can find in the model.
Is TimeLab restricted to 200MHz measurements on 53230A? - Page 1
Forum section: electronics / general

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: December 13, 2021, 08:03:22 pm
content: Is TimeLab (I am using current, v1.55 Beta) restricted to 200MHz top frequency?I am trying to use Keysight 53230A to measure 492.52MHz signal and TimeLab is refusing to let me enter anything over 200MHz - either manually or via "Use incoming data to configure measurement"Is this deliberate feature or a bug?It seems that FA-2 is allowed to have 492.52MHz but not 53230A.CheersLeo

author: TheSteve
author_rank: Unknown
timestamp: December 13, 2021, 08:28:04 pm
content: Are you using the 350 MHz input for a 492.52 MHz signal?

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: December 13, 2021, 08:41:23 pm
content: Yes, is this a problem?Quote from: TheSteve on December 13, 2021, 08:28:04 pm

author: KE5FX
author_rank: Super Contributor
timestamp: December 14, 2021, 10:53:45 pm
content: The 53230A code inherited that limit from my 5370B code base, it looks like. I went ahead and effectively removed the cap by changing it to 100 THz for all of the GPIB counters, just to keep it from being a problem in the future, and posted a slipstream update of 1.55b (date changed, but not the version). You can reinstall fromhere.

author: TheSteve
author_rank: Unknown
timestamp: December 15, 2021, 03:10:39 am
content: Quote from: Leo Bodnar on December 13, 2021, 08:41:23 pmIf it works then it is no problem. I know they added some firmware frequency limits but maybe it was only to the optional 6 and 15 GHz inputs.
Strange nois on FFT when 1kHz it's ok, byt 12kHz spectrum wrong - Rigol DS1054Z - Page 1
Forum section: electronics / general

author: Neurosurg
author_rank: Contributor
timestamp: December 13, 2021, 01:49:55 pm
content: Hi Everything,I have a problem with my Rigol DS1054ZWhen I give him the square signal 1Khz, 10, 100 etc, FFT looks normal, but for f=12kHz, 15kHz, 8hHz etc something goes wrong with the spectrum.Please look at the screen shots. Co-procesor for match is failed ? Help my.Thanks.

author: TUMEMBER
author_rank: Regular Contributor
timestamp: December 13, 2021, 03:15:51 pm
content: You got the departments wrong. This one is about metrology, not repair. You should put the post in the test equipment section. It's not an "electroda.pl" - they did not deign to answer there? Because I saw an identical post there.https://www.eevblog.com/forum/testgear/new-rigol-ds1054z-oscilloscope/

author: RoGeorge
author_rank: Super Contributor
timestamp: December 13, 2021, 03:38:38 pm
content: There is nothing wrong with the oscilloscope, that is how FFT works. Similar FFT leakage will appear for the settings used in the first picture, if the input signal would be 1.2kHz instead of 1kHz.https://www.gaussianwaves.com/2011/01/fft-and-spectral-leakage-2/

author: Scottie
author_rank: Contributor
timestamp: December 13, 2021, 04:28:26 pm
content: I have a DS1054Z and can confirm the FFT function is pretty lousy. As far as I know the FFT operates on the display sample buffer which is likely 1024 points.The scope downsamples the acquisition buffer to display buffer by simply dropping samples. So, many of the square wave harmonics end up aliasing and folding back down to the first Nyquist band.If you FFT a sine-wave input you should have better luck.You can also try adding an FFT window.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 13, 2021, 05:39:42 pm
content: Quote from: Scottie on December 13, 2021, 04:28:26 pmDS1054z has a setting to avoid that. In the FFT settings, on the second page of settings, the "Mode" button can switch between "Trace" (FFT is done using only the samples that are seen on the oscilloscope's display), and "Memory*" (all the captured samples are used to calculate the FFT, not only the samples that are displayed on the screen).In practice, "Memory*" mode will usually give a better frequency resolution of the FFT, but FFT leakage will still happen. Unless the sampling time is an exact multiple of the input signal length, then windowing comes into effect, and FFT will show frequency leaks no matter what.

author: Scottie
author_rank: Contributor
timestamp: December 13, 2021, 10:43:57 pm
content: Quote from: RoGeorge on December 13, 2021, 05:39:42 pmThat is good to know, though I don't ever use the FFT function on the scope, I always run FFTs in Matlab.OP: I see about the same for a 12 kHz square wave. I also included a 12 kHz sine wave (just had to push the sine button on my function generator).