hybridfree/eevblog-posts huggingface dataset:
NAVICOM RCGD-M GPSDO - Page 1
Forum section: electronics / general

author: texaspyro
author_rank: Super Contributor
timestamp: April 01, 2019, 02:48:04 am
content: Recently I got in this GPSDO from China via Ebay. It looks nice, but I have not tried firing it up yet. I have no other info on this GPSDO. Here is what the seller has found out. I have not found any other info on this device... does anybody have some?This GPSDO has two 10 MHz SMA connectors and a MCX (?) antenna connector. It has a 2007 date etched on a PCB. I suspect some of those pins (probably on CON4) has a "management" interface where you can config and monitor the GPSDO, but it does not send data unless polled. Whatever language it speaks is unknown... no documentation. My best guess is it may be like the TL1 stuff like the Star4 and NEC GPSDOs... maybe on CON4 15 .. 18.Signal connectors for NAVICOM RCGD-M GPSDO:CON5:PIN1: 10MHz output, LVTTLPIN2-6,10: UnknownPIN7-8,11,15: should be output, connect to FPGA, LVTTLPIN13,16-18: should be input, connect to FPGA, LVTTLPIN12,14: 39.32MHz clock signal output,LVTTLPIN9: 1PPS outputPIN19-20: power groundCON4:PIN1: 1Hz 50% duty cycle outputPIN2： 1Hz 23% duty cycle outputPIN3-4，6-12: unknownPIN5: TXD(TOD?)PIN13-14: +12V 1A power supply inputPIN15: should be output, connect to FPGA, LVTTLPIN16-18: should be input, connect to FPGA, LVTTLPIN19-20: GND, power groundCON8 (connects two boards together)PIN7: 1PPS signal from GPS receiverPIN9: RXD signal from GPS receiver, LVTTLPIN11: TXD signal from GPS receiver, LVTTL, Baud rate 9600, 8-bits, no parityconnect the TXD to PC via RS232<-> UART Adapter, and we have been used Lady Heather that configures as MOTO receiver to monitor the status of this GPSDO.

author: Morroc
author_rank: Newbie
timestamp: July 10, 2019, 10:29:05 am
content: Got such a gpsdo. He works with Lady Heather, but ... This is the result obtained after about 30 hours of work (I dropped the statistics a couple of times). I saw screenshots of tests of other gpsdo and in them ADEV was in the range of -11 .. -13, on my own in the range of -9 ..- 12 - is such a bad gpsdo or is it possible that I do something wrong?

author: texaspyro
author_rank: Super Contributor
timestamp: July 10, 2019, 08:01:58 pm
content: Heather is only talking to the GPS receiver. It is calculating a "bogo-adev" of the receiver "accuracy" value... which is pretty much meaningless and can't be compared to other devices.I still have no idea of how to talk to this GPSDOs configuration/management interface.
E-H research pulse generators, 135A, 136 etc. - Page 1
Forum section: electronics / general

author: Physikfan
author_rank: Regular Contributor
timestamp: July 09, 2019, 05:58:07 pm
content: To all electronic freaksPlease, is some information available on the specs of E-H research pulse generators, 135A, 136 etc.Also hints to manuals are very appreciated.RegardsPhysikfan

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 10, 2019, 12:31:43 pm
content: I used to have (I think) a 131. It was a really nice pulse generator, but manuals are scarce. You might have to wait and hope something comes up on eBay. The really nice feature of a good pulse generator is the adjustable delay that allows scope triggering exactly where you need it. I eventually sold it, as I so rarely needed that type of generator.
Datron 1281 Questions - Page 1
Forum section: electronics / general

author: LaserEng
author_rank: Regular Contributor
timestamp: July 08, 2019, 08:47:58 am
content: I'm trying to repair a Datron 1281 but I'm having trouble finding a source for the single coil latching relays, in particular RL203 which is a 3A1B type contact relay, does anyone know of a source or an obtainable equivalent?This unit is throwing a lot of zero magnitude errors on low ranges and when examining the pathway readings for zero magnitudes the measured value jumps wildly with some poking, tapping of RL203. I'm not adverse to doing a patch board or two as can be seen from the pic below of someboards made for another instrument I'm fixing up, but it seems that single coil latching relays are pretty much getting unobtaniumand haven't figured a way of patching this relay with normal relay or 2 coil latching relay yetAnother question is if someone knows what needs doing to change from 60Hz to 50Hz mains, all I have been able to see in the manuals is to contact Datron...was sure I had seen a post on the forum explaining the changes but hours of searching and I still couldn't find the post so maybe it was for another Datron meter

author: capt bullshot
author_rank: Super Contributor
timestamp: July 08, 2019, 09:32:43 am
content: Regarding the single coil latching relays:You can use a dual coil one (rated at the same nominal voltage as the single coil), connecting the coils in series - this gives you the equivalent single coil relay.

author: guenthert
author_rank: Frequent Contributor
timestamp: July 08, 2019, 03:41:32 pm
content: I can't speak of the 1281, but for the 1271 the switch from 60 to 50Hz was trivial. iirc, it's a setting in the calibration menu (unlike the switch from 110 to 220V, which is in the back of the unit and needs to be done before powering onUnfortunately I have currently no access to the unit or the manual.

author: syau
author_rank: Frequent Contributor
timestamp: July 08, 2019, 04:05:33 pm
content: The line frequency can be changed as per page 4-51 of User’s Handbook

author: Testtech
author_rank: Regular Contributor
timestamp: July 09, 2019, 10:38:42 pm
content: You can, and I have, on some relays of this type, carefully removed the relay from the PCB, and, carefully, remove the cover of the relay, and clean the contacts. The cover is epoxy attached only around the periphery. This is fairly easily "cracked" away from the base, allowing the cover to be removed.Some other types this is not possible, however two small holes can be drilled into the cover with a pin vise, allowing for your favorite DEOXIT type cleaner to be injected into the relay, and subsequently the excess blown out.After that, you can connect the relay to a pulse generator for exercise.This often will clean up a dirty relay.On the other hand, the 1281's I have repaired the relays were available, made by Panasonic as I recall. Not cheap, and perhaps difficult to source in your area.
EFOS Maser prototype in museum display - Page 1
Forum section: electronics / general

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 17, 2019, 04:01:56 pm
content: Thought I'd share this PIX of the EFOS series Maser prototype with the shields retracted and the bulb exposed. "Time-Nuts porn!Corby

author: uncle_bob
author_rank: Unknown
timestamp: July 17, 2019, 06:13:25 pm
content: HiI'm sure I could machine one up in the garage .... notBob
Fluke 5700A VFD displays - Page 1
Forum section: electronics / general

author: jfphp
author_rank: Regular Contributor
timestamp: June 28, 2019, 09:55:04 am
content: Hello,I a looking for the manufacturer and part numbers of the 2 displays of the Fluke 5700A first generation (serie 1). Thank you

author: TiN
author_rank: Super Contributor
timestamp: June 28, 2019, 09:59:12 am
content: I'll check my photos of the display boards, but afaik any identification labels would be on the back side of the glass, which is not accessible.And VFDs in all 5700 series including 5790A are same (but may have multiple manufacturers since 1989).
WTB: Fluke 731B Voltage Reference - Page 1
Forum section: electronics / general

author: Echo88
author_rank: Frequent Contributor
timestamp: March 03, 2019, 08:14:04 pm
content: I want to buy a Fluke 731B Voltage Reference for a reasonable price. If somebody has one and wants to sell it, please write me a PM with your price suggestion.Thanks,EchoEdit: Deleted EU-only-condition.

author: Echo88
author_rank: Frequent Contributor
timestamp: July 02, 2019, 11:45:23 pm
content: Bump

author: Echo88
author_rank: Frequent Contributor
timestamp: July 08, 2019, 12:14:43 pm
content: Moved topic from Market to Metrology, maybe here are more owners who want to give 731Bs a new loving home?

author: try
author_rank: Regular Contributor
timestamp: July 08, 2019, 12:19:05 pm
content: You should ask user HighVoltage if he currently owns one.Regardstry

author: Echo88
author_rank: Frequent Contributor
timestamp: July 08, 2019, 12:21:31 pm
content: I did a few months ago, sadly he didnt have any remaining 731Bs to sell.
Plugs to fit rear panel circular connectors for Datron 4808 - Page 1
Forum section: electronics / general

author: perdrix
author_rank: Frequent Contributor
timestamp: July 11, 2017, 11:37:49 pm
content: They look like the mating connectors might be Lemo FGG.2B.306.CLAD92Z but I'd like confirmation if possible before firing off an order as they aren't dagger cheap.ThanksDave

author: Vgkid
author_rank: Super Contributor
timestamp: July 11, 2017, 11:42:05 pm
content: Pictures.

author: quarks
author_rank: Frequent Contributor
timestamp: July 12, 2017, 01:05:15 am
content: As I have already written elsewhere, the original connectors are from LEMO.In the 4808 and 4600 are EGJ.2B.306 and EGG.2B.306.The mating plugs are FGJ.2B.306 and FGG.2B.306.You can get them in crimp and solder versions.I personally much prefer to crimp,But crimping is only an option, if you also have the necessary crimp tools.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 12, 2017, 08:08:49 am
content: Thank youDave

author: perdrix
author_rank: Frequent Contributor
timestamp: July 12, 2017, 08:31:55 am
content: Just to be 100% sure - I think these are wired straight through 1-1, 2-2 etc. Is that correct? Is that same also true of the Db15 cables?Thanks again, Dave

author: quarks
author_rank: Frequent Contributor
timestamp: July 12, 2017, 02:46:37 pm
content: If I remember correctly all cables are just 1 to 1 connections

author: syau
author_rank: Frequent Contributor
timestamp: June 28, 2019, 02:22:53 am
content: Found some alternative from Aliexpress:Male Plug LEMO FGG.2B 6 pinhttps://s.click.aliexpress.com/e/dbm34MCFemale Plug LEMO FGG.2B 6 pinhttps://s.click.aliexpress.com/e/b9WHYO64Have ordered some pieces, the build quality is excellent.Tested both connectors on my 4708 and 4600, they are mechanically fit.
GPSDO time constant - Page 1
Forum section: electronics / general

author: Ohm_My
author_rank: Contributor
timestamp: June 17, 2019, 01:30:43 am
content: I have one of these eBay GPSDO units that has the Oscilloquartz 8663-XS oscillator (STAR 4+) and I use it to steer a Rubidium standard. What does the time constant value perform and is their an optimal setting? I believe the range for the time constant is 200 seconds and can be adjusted to a max value of 5,000 seconds, I think.I'm also using using Lady Heather 6.14 b16 to monitor the progress. I'd like to hear from anyone who has a similar setup or experience with this GPSDO unit.Thanks.

author: jpb
author_rank: Super Contributor
timestamp: June 17, 2019, 05:04:00 pm
content: I think that 200 seconds is way too short. I have mine set to 5000 seconds and am (slowly) doing some ADEV measurements - unfortunately my setup is only able to give measurements above around 10 seconds. From what I've measured so far a time constant of around a 1000 seconds is probably good.The GPS signal itself doesn't reach an ADEV of 10^-11 until about 2000 seconds with it being around 8 x 10^-12 at around 4000 secs - see this app notehttps://www.u-blox.com/sites/default/files/products/documents/Timing_AppNote_%28GPS.G6-X-11007%29.pdfmy measurements for one Star 4+ vs another (I have two) with both set to 5000 seconds are all below 10^-11 (and you need to divide by root(2) if they are identical) so I think the OCXO is probably below 10^-11 out to a few thousand hence I argue a setting towards the high end (a few thousand) is probably best.

author: Theboel
author_rank: Frequent Contributor
timestamp: June 17, 2019, 09:52:33 pm
content: Hi Ohm_My,Sorry I confused with Your post.what Time constant You ask for ? is the time constant in internal GPSDO (For OCXO) or time constant for steering RB ?

author: Ohm_My
author_rank: Contributor
timestamp: June 18, 2019, 02:27:24 am
content: Quote from: Theboel on June 17, 2019, 09:52:33 pmI'm assuming it is the TC for the GPSDO OCXO. I'm using the TC from the Rb to do the steering.

author: David Hess
author_rank: Super Contributor
timestamp: June 18, 2019, 10:45:36 pm
content: The GPSDO time constant to set depends on the stability of the local oscillator; higher stability oscillators can use longer time constants to produce better results.Ultimately the time constant sets the break point between the noise curves from the local oscillator and GPS signal. The local oscillator controls the output for time periods faster than the time constant and the GPS signal controls the output for periods longer than the time constant.
TICC-TAC-TADD!  Opinions wanted.  (mainly TAPR stuff question) - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: June 23, 2019, 04:51:02 pm
content: I am making a TAPR TICC and TADD2-mini combination unit.TADD2-mini allows output to be synchronized with external standard. Say there is a 10MHz coming in. TADD makes it into 1pps. If there is another pps connected (say from GPS) it can synchronize with that. As I understand it, this happen once only. Next count is on its own without syncing.I could, for example, sync it with reference input, or sync it with second TADD2-mini. Either way, two signal will start exactly in sync first then let it drift.What I am not sure is, with TICC, is it even necessary?Does anyone think there will be a need for it?---------------My current plan2 TADD2-minis. In and out connector on front panel. 1/2.5/5/10MHz selector on front panel. 1 pps LED on front panel.1 PICC. In connector on front panel. "now measuring A" and "now measuring B" LED on front panel. Reference input, on front panel. (no internal reference) USB on front panel. I am not quite sure why I need the LED... doesn't "reading" happen simultaneously? Are there a mode that I'm not aware of where counting happens only on one or alternately?I don't plan to make this into a Swiss army knife. Flexible to a degree but nothing more.Opinions and Ideas, please.

author: awallin
author_rank: Frequent Contributor
timestamp: June 24, 2019, 04:23:17 am
content: Quote from: tkamiya on June 23, 2019, 04:51:02 pmre "exactly": I believe the sync input of a PICDIV/tadd2 synchronizes the output 1pps to within one cycle of the input-frequency, e.g. 100ns for 10 MHz.Quoteif the single-shot noise of the TICC is acceptable for you then it is a cheap time-interval counter for measuring how the two 1PPSs move relative to each other.The TICC has on-board LEDs which show when ch1 and ch2 trigger IIRC. The TICC will need a 10MHz reference frequency that defines the timebase.Something like a SR620 or Keygilent 53230A is lower noise but costs more.If you want to DIY there are lots of variations of the picdiv out there. I've made a board like this:https://github.com/aewallin/PICDIV_Board_v3AW

author: tkamiya
author_rank: Super Contributor
timestamp: June 29, 2019, 03:42:04 pm
content: Thank you.Now I have/had the unit, it appears syncing isn't necessary at all. So I have it not set up that way. Yes, there are two LEDs, one for each channel. But what they do is, illuminate when each channel enters LOOP in the program. Because it measures both channels almost simultaneously, they blink together for human eyes. I thought it will detect arrival of input pulse, but it really doesn't look that way.Thanks for your reply.

author: texaspyro
author_rank: Super Contributor
timestamp: June 29, 2019, 05:24:07 pm
content: Quote from: tkamiya on June 29, 2019, 03:42:04 pmOn mine, they seem to blink with the pulses. I can see two distinct blinks when feeding it non-synchonized inputs.
any diy PTP/ieee1588 grandmaster clock builds?  (high precision 'ntp' like) - Page 1
Forum section: electronics / general

author: linux-works
author_rank: Super Contributor
timestamp: June 11, 2019, 06:37:43 pm
content: for a project at work, we need to get high precision network time. the standard for us will be PTP (ieee 1588 v2).I've seen (and built) an ntp rasp pi server that uses gps and pps. that was a fun build.from what I understand, the precision time clock for PTP is held in the network card (nic). is that always true?I do see some linux opensource PTP code and I'm wondering if anyone tried building one and how it compares to commercial grade GPS-DO based network master clocks?so far, I'm thinking the only special hardware I need is a pps-enabled gps module, a way to send the pps into the kernel (serial DCD/DTR line?) and buying a 1588 capable NIC (intel i210 I think can do it). but there are probably details I'm not seeing.any experience in this, from a DIY pov?

author: jbb
author_rank: Super Contributor
timestamp: June 12, 2019, 07:47:55 am
content: I haven’t done it myself, but I believe that if you want real precision time you buy a GPS time server which does the most critical PTP master in hardware.You could have a look at the White Rabbit stuff from CERN? It’s open source and bonkers precise/accurate. As it’s open source you can go in and look at how they did their PTP stuff.

author: ogden
author_rank: Super Contributor
timestamp: June 12, 2019, 08:24:36 am
content: Such way you can't make anything better than NTP you already did. You miss inherent jitter of software/CPU based solutions. 1588 needs OCXO high stability local oscillator and FPGA for processing. In short: buy it.

author: dkozel
author_rank: Regular Contributor
timestamp: June 13, 2019, 08:07:55 pm
content: WhiteRabbit is excellent and CERN has posted all of the materials needed to make a commercial grade timing reference. A downside is that all the switches in your network path need to be WhiteRabbit capable as well, which CERN also has designs for. Maybe a bit premature or overkill for a house installation, but doesn't stop me from wanting it!https://white-rabbit.web.cern.ch/

author: LapTop006
author_rank: Unknown
timestamp: June 16, 2019, 07:06:50 am
content: I've worked on building a homebrew high quality SyncE source, but haven't actually gotten to the point of testing that (other shiny projects).PTP isn't inherently better than NTP, you can do the same sort of hardware assist for NTP, and without the hardware assist PTP is no better than NTP.If you actually need sub-ms time referencing there's a lot more to it than just time sync, have a read of theSpanner/Truetime paperfor a start.If I had to use PTP or SyncE, I'd almost certainly start with the White Rabbit project, as, unlike most of the vendors, they've actually got demonstrated results.
Measuring low voltages with Keithley 155 and 181 - Page 1
Forum section: electronics / general

author: kj7e
author_rank: Frequent Contributor
timestamp: June 13, 2019, 04:36:03 pm
content: Fun video;

author: MiDi
author_rank: Frequent Contributor
timestamp: June 13, 2019, 04:47:38 pm
content: I like Marcos special humor.My favourite is "Physikalisch Technische Badeanstalt" in his LTZ1000 VideoHe lives not far from me...I wonder if Marco is registered here - if so please give a "piep"

author: Kean
author_rank: Unknown
timestamp: June 13, 2019, 08:32:44 pm
content: Quote from: MiDi on June 13, 2019, 04:47:38 pmYep, he is EEVblog user baltersice. He doesn't post too often - I imagine he is a little too busy.
Repair Fluke 5500A Error 104 - Page 1
Forum section: electronics / general

author: Regiano
author_rank: Newbie
timestamp: April 13, 2019, 04:32:15 pm
content: I had a problem and entered 220V at the input of my fluke 5500A Calibrator , now it is turning on ERROR 104 trip relay, can someone help me with this defect.thanks

author: chinapp
author_rank: Contributor
timestamp: June 09, 2019, 05:10:48 am
content: encounted the same error,looking for help too.....

author: TiN
author_rank: Super Contributor
timestamp: June 09, 2019, 05:14:53 am
content: You guys no help, with lack of details. 5500A is not a simple box to troubleshoot, so what steps you tried to narrow down the issue?Trips on every function/range? Some ranges? Protection circuits would be first thing to check. 5500A schematics also available, if this is your personal unit or you have confirmed approval from owner to risk DIY repairs

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: June 09, 2019, 11:48:17 am
content: Seems like we should set up a ship to address to investigate these errors. Send them to xDevs c.o. TiN for troubleshooting.

author: Theboel
author_rank: Frequent Contributor
timestamp: June 09, 2019, 02:02:50 pm
content: with the cost of 5500 even in the ebay I think rent a ship to send two pcs 5500 to taiwan is good plan
the smallest GPSDO in the world - Page 1
Forum section: electronics / general

author: testpoint1
author_rank: Frequent Contributor
timestamp: June 07, 2019, 03:53:04 am
content: I designed, for the GPSDO, the "O" is VCOCXO, it can use the ref port generate 30.72MHz signal, use the 1pps port (TP2) generate 1-24MHz, signal, but the frequency must be divided exact of 24MHz, such as 4MHz, 8MHz, 12MHz etc, if you want to generate 10MHz, it can, but, terrible.
Some questions for the new bench - Page 1
Forum section: electronics / general

author: Zenwizard
author_rank: Regular Contributor
timestamp: June 02, 2019, 03:59:21 pm
content: So I might spark some heated debate with this one but here we go.Recently I am torn down the lab in an effort to redo all the lighting and the walls This included a large electric upgrade to support the bench as well as a new bench to work from. And that is my conundrum. I am interested is “checking in” all the equipment as it goes back on the bench. But most of the gear is second hand and in an unknown call state. I was debating on getting a Mantis for the bench for putting it back together. However as the goal has changed I am leaning to getting a new Bench multi meter and doing a cal check on all the gear as it comes back on the bench. I have a few analog scopes the 2 important ones are a 7603 and I recently got a 7904 that needs to be check as well as a lot of TM gear a few oscillators and function generators and signal sources. The bench meter I am looking at is a Keithley 7510 7.5 digit? If I get the meter I’ll have to put off the mantis a while or get the mantis and forgo for meter for a while. Also can anyone recommend a good frequency counter or at least a good place to start gathering some information about them.Thanks for the inputZen

author: Vgkid
author_rank: Super Contributor
timestamp: June 02, 2019, 05:36:36 pm
content: What frequency are you going to measure up to, size, , cost(is used fine).HP 5335 is a good <200mhz f-counter.

author: Grandchuck
author_rank: Super Contributor
timestamp: June 02, 2019, 06:18:11 pm
content: First, the Keithley is a very nice meter (looking at the specifications). My meters are Fluke, Keysight and Agilent but I do have past experience with Keithley and like their stuff. I don't have a decent vision system but use a cheap USB microscope ... works OK for hobby level work.My frequency counter is a HP 5385A bought used. It works great but it did fail once. It was a just a filter in the power supply, so very easy to fix. There are lots of used counters out there. Were you looking to buy new?My lab is overcrowded and I need to do something else now. I have added two DMMs since the photo was taken.
HP Agilent 4339 calibration software - Page 1
Forum section: electronics / general

author: n1dny
author_rank: Newbie
timestamp: May 30, 2019, 10:25:54 pm
content: Hi,Does anybody have a copy of the calibration software for the HP 4339? It is part number 04339-65008. It runs on the old HP 9000 series and HP Basic.
An almost-GHz active differential oscilloscope probe - Page 1
Forum section: electronics / general

author: GilbouFR
author_rank: Contributor
timestamp: June 05, 2019, 10:29:48 am
content: http://blog.weinigel.se/2016/02/26/ghz-differential-probe.html

author: cat87
author_rank: Regular Contributor
timestamp: June 06, 2019, 12:52:48 pm
content: I saw this projectsome time ago and seemed interesting but kinda got me wondering about the actual, real life CMRR of the thing.Would be really curious to see what a VNA has to say about such a probe

author: Geatnows
author_rank: Newbie
timestamp: June 11, 2019, 06:57:22 am
content: If you can do it yourself, if you have time, I believe you can do it.

author: guenthert
author_rank: Frequent Contributor
timestamp: June 16, 2019, 06:22:42 pm
content: Quote from: cat87 on June 06, 2019, 12:52:48 pmIsn't that exactly what they did inhttp://blog.weinigel.se/2016/03/16/ghz-differential-probe-3.html"At this stage I pestered a colleague into running the probe through a network analyzer to see how it would do."

author: cat87
author_rank: Regular Contributor
timestamp: June 18, 2019, 07:45:28 am
content: QuoteIndeed, he did. I think I misspoke. What I meant was that I was curious about what the CMRR vs. Frequency looks like.The author of that article checked only the Gain vs Frequency of the probe.
Sources of information (ie books) on polishing and lapping - Page 1
Forum section: electronics / general

author: jeremy
author_rank: Super Contributor
timestamp: May 23, 2019, 12:28:36 pm
content: Hi all,Not sure if this is the right area to ask this in, but it is concerned with unreasonable levels of pedantry, so I thought this might be the bestI’m looking for some books and other sources on lapping and polishing techniques. In particular, making first surface mirrors, and also for making parallel/precise angled and flat surfaces on various metal objects.If anyone can point me toward some classics that would be great!

author: Andy Watson
author_rank: Super Contributor
timestamp: May 23, 2019, 01:14:51 pm
content: John Strong's book "Procedures in Experimental Physics" covers the basics. It's a bit old but the techniques are still valid. You might also look at books on telescope construction - Jean Texereau's "How to Make a Telescope" for example.

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: May 23, 2019, 02:36:25 pm
content: The classic is "Amateur Telescope Making vols 1,2,3 by Ingalls.https://www.willbell.com/tm/tm7.htmDistilled knowledge is here:http://bobmay.astronomy.net/johnpierce/part8.htmthis search returns good stuff "amateur telescope making optical flats"

author: coppercone2
author_rank: Super Contributor
timestamp: May 25, 2019, 01:23:19 am
content: https://www.scribd.com/document/367983682/Foundations-of-Mechanical-Accuracy-by-Wayne-R-Moore-1970This has stuff on lapping, but for metal things, i.e. see page 65
Datron 4000 Operation Sense Display - Page 1
Forum section: electronics / general

author: Johnny10
author_rank: Frequent Contributor
timestamp: May 24, 2019, 11:56:43 pm
content: I am wondering about the sense mode in the Datron 4000 Calibrator.When the sense button is pressed in DC mode does the Left display show an actual voltage reading at the terminals or is this a look up reading from calibration data?

author: Johnny10
author_rank: Frequent Contributor
timestamp: May 25, 2019, 12:35:51 am
content: OK after reading through the user manual I understand this better.Remote sense over 1V in output measures at the Load terminals.Local Sense at the Datron 4000 terminals.I guess I crossed the description of Resistance measurements with Voltage.Where Resistance Output display is the measured value of resistance at calibration.
Solartron 7061 system voltmeters - Page 1
Forum section: electronics / general

author: frantisek
author_rank: Regular Contributor
timestamp: May 23, 2019, 07:22:54 am
content: Hello! Greetings to all colleagues and much for advice. I have a Schlumberger 7061 system voltmeter. All OK tests are running, but zeroing is not possible when trying to calibrate ... The service has said that it needs to be done by software but does not have the necessary equipment. Can someone please help or advise? Thank you!
Changing to the 2019 SI Redefinitions on May-20 - Page 1
Forum section: electronics / general

author: Magnificent Bastard
author_rank: Regular Contributor
timestamp: May 17, 2019, 05:32:37 pm
content: This post was stolen from:Changing to the 2019 SI RedefinitionsOn May 20, 2019 new values will be implemented for the International System of Units (SI) base units of the kilogram, Kelvin, mole and ampere, and the derived units of the volt and ohm. These values are based on redefinitions of the Planck constant, elementary charge, the Boltzmann constant and the Avogadro constant. The changes are based on the evolution of the definition of the kilogram, which has progressed from a physical artifact—held at the International Bureau of Weight and Measures (BIPM) since 1889—to a constant of nature, Planck’s constant, that can be accessed anywhere in the universe. This change benefits the entire world in potentially having better access to realization of the kilogram, and eliminates the risks associated with maintaining a standard that is based on a sole artifact. As a result of the redefinitions, some measurement reference standards must be adjusted to the new value of the definition. Other measurement reference standards may account for the redefined value by incorporating an additional contributor to their measurement uncertainty evaluations. The attached application note summarizes the changes being made and provides guidance on how to implement them.

author: mzzj
author_rank: Super Contributor
timestamp: May 18, 2019, 11:06:58 am
content: "The International Committee of Weights andMeasures (CIPM) Consultative Committee on Electromagnetic Quantities (CCEM) has produced aguideline which states that no action is requiredif your voltage related uncertainties are largerthan 0.25 ppm5. If your uncertainty for the voltis less than 0.25 ppm and you do not have directaccess to a JVS, we recommend that you add the0.107 ppm adjustment quantity to your uncertainty analysis."Unfortunately I don't have any voltage standards with calibration uncertainties below 0.25ppm
Looking for a gas tight triax feedthrough - Page 1
Forum section: electronics / general

author: Henrik_V
author_rank: Regular Contributor
timestamp: May 09, 2019, 01:22:47 pm
content: I would like to build a box flooded with dry N .(rebuild/mod a 1404 capacitor)The idea came up to replace the feedthroughs with triax ones ...

author: Vgkid
author_rank: Super Contributor
timestamp: May 09, 2019, 09:35:14 pm
content: Trompeter bj157hs far from cheap...

author: babysitter
author_rank: Frequent Contributor
timestamp: May 10, 2019, 06:56:58 am
content: There are feedtrough caps with a hole in the center to place your own wire. Try matrjoschkafication of those.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: May 10, 2019, 07:26:53 am
content: As I expect the dry N pressure will be close to atmospheric.Then You may consider using as a barrier typical double sided PCB with metalized vias filled with solder + RTV silicone (or silicone o-ring) seal to the enclosure.

author: David Hess
author_rank: Super Contributor
timestamp: May 10, 2019, 05:16:59 pm
content: I would consider using hermetic feed-throughs with a normal triax connector.

author: IconicPCB
author_rank: Super Contributor
timestamp: May 11, 2019, 01:23:38 am
content: Just checked Tusonics...Still exist in a somewhat different guise, worthwhile going through their offeringhttps://www.ctscorp.com/products/connect-products/emirfi-filters/
Fluke 752A 10:1 Input Resistance - Page 1
Forum section: electronics / general

author: LKM
author_rank: Newbie
timestamp: November 30, 2018, 11:13:26 pm
content: Hi All,Does anyone know why the input resistance of the 10:1 divider is 380kOhm and not the expected 400k?In the 100:1 divider the input resistance is 2M instead of the expected 4M because there is a 4M divider chain in parallel to guard each of the 30R strings which are in metal cans.I'm assuming a similar situation is present in the 360k divider string of the 10:1 but so far I'm not seeing it described in the manual or schematic. There is mention of a passive guard but no resistor divider for the 10:1 section.I calculate 6.12Mohm in parallel with the 360k to give 340k but I'm not sure from where.Thanks!

author: dacman
author_rank: Frequent Contributor
timestamp: December 01, 2018, 03:15:28 am
content: Because the 100:1 divider resistors are still in the circuit. Above the 10:1 divider is 3.6 MOhm from the 100:1 divider which is now in series with the 4 MOhm of guard resistors. That is 7.6 MOhm in parallel with 400 kOhm, which is 380 kOhm. This value is in a troubleshooting chart in the back of the manual as the correct value.

author: seoma
author_rank: Newbie
timestamp: December 09, 2018, 08:18:35 pm
content: Hello dacmanI think your studies on electronics are very highThank you for answering the questionGive more guidanceThanks

author: LKM
author_rank: Newbie
timestamp: April 26, 2019, 12:47:33 am
content: Found these notes cleaning my desk, figured I'd post for posterity. dacman's info checks out
GPS self-survey - what is this for? - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: May 23, 2019, 08:52:22 pm
content: I've been wondering about GPS self-survey. This subject is difficult to google as all it will bring up is differential GPS and Geo-spatal survey subject. That's not what I am wondering.For example, Thunderbolt has a command to start a self-survey. Acquire 3 satellite and self-survey starts automatically. Or, one can initiate manually. In case of True Position, there is a $SURVEY command that takes length as an argument. My understanding is, minimum of one satellite is required for timing information. 2 is required for 2 dimensional fix. 3 is required for 3 dimensional fix. At this point, location of the receiver antenna is known. More satellite is locked in, accuracy improves.Then, why does it need to spend 8 hours (default for True Position) surveying? What is it doing exactly? Is longer the better? Why is it even necessary? Seems having locked to satellite is enough to do 3 dimensional triangulation and time.If someone can explain this to me, I'd appreciate. Or, if you can point me to a resource, that will be helpful too. Thanks.

author: edpalmer42
author_rank: Super Contributor
timestamp: May 23, 2019, 09:05:26 pm
content: The biggest reason for a self-survey is our old friend, noise. LH has a command that will continuously plot the position. According to that plot, your GPS antenna (and maybe your house) is dancing around your lot!A nice long survey will average out the noise and determine what your actual position is.Why do you care what your position is? We're interested in timing, not location, aren't we?Well, yes and no. If there's an error in your position, it will cause timing glitches - particularly when a satellite enters or leaves the group of satellites that the receiver is using to determine the timing of its outputs. If the receiver has a good idea what its location is, it can reject bogus info or timing from a satellite and minimize those glitches.Ed

author: tkamiya
author_rank: Super Contributor
timestamp: May 23, 2019, 09:08:08 pm
content: THANK YOU! That's very clear and concise, even for me.
MEMS based voltage references - Page 1
Forum section: electronics / general

author: branadic
author_rank: Super Contributor
timestamp: April 10, 2019, 07:38:38 pm
content: Hi,I read about "MEMS based voltage references" (you can google that)MEMS based voltage referencesMEMS-based AC voltage referenceI wonder if anyone have heard of that before and has experience with it? For DC they still seem to be of none interest for volt nuts, but for AC they seem to perform not that bad...-branadic-

author: Kleinstein
author_rank: Super Contributor
timestamp: April 10, 2019, 08:36:39 pm
content: It is an odd idea and I don't see it really working that well. I did some work with bulk MEMS structures my self, but never god the idea of using it as a voltage reference - more like as an VCO with a little more pull range than a VCXO.A point that worries me in this application is the surface oxide layer. If very thin or no oxide one would have to expect some more growth of the oxide which would via surface stress cause large shifts. If there is a significant oxide already, the oxide can react to humidity, even tiny amounts, like a fraction of a surface layer. To this level even the TO8 can may not be sealed enough. At least from my experience with a possibly different oxide layer, the time to equilibrate with humidity is more like in the months to years at room temperature - so just the wrong time scale.
Is this scope probe worth 100 bucks 300Mhz - Page 1
Forum section: electronics / general

author: ebclr
author_rank: Super Contributor
timestamp: April 06, 2019, 05:32:57 pm
content: Is this scope probe worth 100 buckshttps://www.amazon.com/Probe-Master-4906-1K-Passive-Voltage/dp/B01D13IH48/ref=sr_1_95?qid=1554571734&s=gateway&sr=8-95&srs=8469375011

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: April 06, 2019, 05:40:46 pm
content: Hard to say. It has a nice collection of attachments and the bandwidth is good, but I like to have several matched pairs, so wouldn't be willing to spend that much for home.

author: Grandchuck
author_rank: Super Contributor
timestamp: April 06, 2019, 07:04:31 pm
content: Less money ($82) on the Probemaster site?

author: Johnny10
author_rank: Frequent Contributor
timestamp: April 07, 2019, 11:28:10 am
content: A NOS Tektronix 6139A or B probe with extras would be a better deal at around 100+ dollars.

author: ebclr
author_rank: Super Contributor
timestamp: April 07, 2019, 09:49:31 pm
content: Apparently P6139A is obsoletehttps://www.mouser.com/ProductDetail/Tektronix/P6139A?qs=HJSulGd0C6yYRC6QzSv1mg%3D%3D

author: Johnny10
author_rank: Frequent Contributor
timestamp: April 07, 2019, 11:50:26 pm
content: https://www.ebay.com/itm/Tektronix-P6139B-500-MHz-10X-Passive-Probe-Brand-NEW-Package-of-2-Probes/401741175574?epid=17018079579&hash=item5d89a3db16:g:4FcAAOSwbBpclo21Similar to Sold onehttps://www.ebay.com/itm/Tektronix-P6139B-500MHz-Oscilloscope-Passive-Probe-/173850904158?epid=6016220626&hash=item287a52465e%3Ag%3AqZ4AAOSwTHlcmXKn&nma=true&si=I0bOTGPF8Zdx9Kj5t3%252B51b%252FUuFI%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557
Yokogawa 2554 Portable DC Voltage/Current Standard - Page 1
Forum section: electronics / general

author: mlopes
author_rank: Newbie
timestamp: December 29, 2018, 02:23:51 pm
content: Hello all,I have scored a Yokogawa 2554 Portable DC Voltage/Current Standard, which is "almost" in good condition. Does anyone have a service manual for this equipment?Thanks in advance.

author: factory
author_rank: Super Contributor
timestamp: December 29, 2018, 10:29:31 pm
content: Service manuals (or any manuals) seem very hard to find for Yokogawa stuff, but at least the instruction manual (with calibration procedure) is available on ebay;https://www.ebay.com/itm/123569097576David

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 29, 2018, 11:02:47 pm
content: I got one of these waiting for its time on the healing bench.Here's all I could get from Yokogawa Japan.Let me know if you find an English version.

author: mlopes
author_rank: Newbie
timestamp: December 30, 2018, 05:42:33 am
content: Thank you very much for your help!

author: mlopes
author_rank: Newbie
timestamp: December 30, 2018, 05:44:29 am
content: Thanks David,I will check if the seller can send it to Brazil. At least in the item description seem this is not possible.Regards,Marcelo.

author: TERRA Operative
author_rank: Super Contributor
timestamp: January 02, 2019, 08:43:20 am
content: Mlopes, do you have a scanner?If you find an English manual, do you mind scanning it to a .pdf and posting a link here?

author: mlopes
author_rank: Newbie
timestamp: January 05, 2019, 02:49:45 pm
content: Yes, I do. As soon as I get it, I will let you know. The only problem is that the "soon" depends on the Brazilian customs, which are completely unpredictable. I have bought the manual from a German seller on ebay and I think it will take at least one month to arrive at me (from Germany to Brazil should take less than one week, but here will take plenty of time until it arrives).

author: ebclr
author_rank: Super Contributor
timestamp: January 05, 2019, 04:03:59 pm
content: This may helps ( isto Talvez ajude )http://bugworkshop.blogspot.com/2013/03/yokogawa-2554_21.html

author: JZEPaet
author_rank: Newbie
timestamp: March 31, 2019, 09:15:48 am
content: Little late to the party but I managed to pick one up off eBay, owner included a manual with it so I scanned and linked it for those who need it. (or stumble on this thread in the future)https://www.mediafire.com/file/vfc9wbulykmh8i1/Yokogawa+2554+DC+Calibrator+ENGLISH.pdf

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 31, 2019, 12:14:37 pm
content: Nice, thanks for that!

author: alm
author_rank: Super Contributor
timestamp: March 31, 2019, 09:09:32 pm
content: Quote from: JZEPaet on March 31, 2019, 09:15:48 amThanks for sharing this! Would you mind if I upload this to the common sites for test equipment manuals like KO4BB and xdevs.com?

author: JZEPaet
author_rank: Newbie
timestamp: March 31, 2019, 09:14:26 pm
content: Quote from: alm on March 31, 2019, 09:09:32 pmGo for it
Geller Labs site finally gone, contents capture - Page 1
Forum section: electronics / general

author: Gyro
author_rank: Super Contributor
timestamp: March 21, 2019, 06:13:26 pm
content: It looks as if Joe Geller's lab site has finally been taken down, not surprising as it had been lingering (minus some files and images) for a least a couple of years longer than he indicated.I thought it might be a good idea to start a thread to try to capture as much archived stuff from the site as possible. Contributions welcome.I have a reasonable amount of stuff relating to the SVR / SVR-T and a few other bits but I never downloaded his LM399+AD587 reference (I only have the patent file), Micro-gust anemometer, Resistor Noise measurement, Magnetometer (?), Investigation into small value AC measurements on HP DMMs etc.I've attached what I have anyway (all ZIPs, include HTML files(Firefox) and jpgs:- SVR SVR-T Winding Down - Construction information, including temperature compensation text from Lars, and thought about winding down the lab.- SVR Temperature Coefficient Setup - The test rig he used for characterising SVRs and SVR-Ts, including pictures.- 10 1 Reference Divider 752 Junior - His experimental Hamon divider. Missing bottom view and XLS file.- 6 1_2 Digit DMM Temperature Coefficients - His 61/2 digit temperature coefficient measurement page (missing all attachments).- Misc PDFs (self explanatory)As always, use your own cautions when opening files!Other contributions welcome.

author: edpalmer42
author_rank: Super Contributor
timestamp: March 21, 2019, 06:20:38 pm
content: The Internet Archive seems to have all the content. Is it worthwhile to duplicate that here?https://web.archive.org/web/20130607180940/http://gellerlabs.com/Ed

author: Gyro
author_rank: Super Contributor
timestamp: March 21, 2019, 06:36:40 pm
content: Ah, good thought, Thank you. It hadn't even occurred to me that it might still be available there!EDIT: Although it seems to be missing some of the same JPGs as I am.

author: edpalmer42
author_rank: Super Contributor
timestamp: March 21, 2019, 06:56:42 pm
content: Ialwayscheck the Internet Archive when I come across a broken web page or a link to a shutdown site ........ unless I forget .....Ed
Help ID-ing Elektor sig gen - Page 1
Forum section: electronics / general

author: alex.caciu
author_rank: Newbie
timestamp: March 19, 2019, 12:12:51 am
content: Hi all,Can anyone point me to the proper name and/or schematic for this piece of kit (maybe the issue of elektor magazine in which I can find out more about it, if anyone remembers it that specifically)?A friend bought it for me off ebay and will send it my way in a couple of days, but when he tried testing it, he ran into what appears to be a coupling issue, and I'd like to find out more before I go digging around in its innards. So far, all I have is this picture, and another few with the case off. No markings anywhere on it. Will post more in repairs once I receive the package, if anybody's interestedThanks !

author: Andy Watson
author_rank: Super Contributor
timestamp: March 19, 2019, 12:29:07 am
content: Looks like another XR2206 variation. Try this:https://archive.org/download/ElektorMagazine/Elektor%5Bnonlinear.ir%5D%201985-01.pdfShould resolve to January 1985 edition of Elektor.

author: alex.caciu
author_rank: Newbie
timestamp: March 19, 2019, 06:09:40 am
content: Spot on! Thank you very much !
Comparing standard deviations - Page 1
Forum section: electronics / general

author: Grandchuck
author_rank: Super Contributor
timestamp: February 16, 2019, 07:22:23 pm
content: Here are two graphs comparing two meters. The data were collected on separate one-hour runs, but other conditions were the same or reasonably constant: temp, rel hum, and NPLC (100). The meters were on for 8 hours before the data were collected.The reference has been running continuously for months and has proven to be stable. It is based on an LTZ1000 and an AD5791. However, some of the variance is due to the reference.

author: Moon Winx
author_rank: Regular Contributor
timestamp: February 16, 2019, 07:51:50 pm
content: Do you have a question? Or what is the context for this?

author: unitedatoms
author_rank: Frequent Contributor
timestamp: February 16, 2019, 11:22:40 pm
content: Great data. I guess the questions could be- how to estimate noise of reference Nref, when there are two independent instruments with their own noise N1 and N2 ?- if estimate is possible, then are two instruments giving a confidence about Nref when they provide agreeable values? i.e. if Nref1==Nref2 then Confidence==true ?- how to measure own N1 and N2?- how to explain that N1<<N2 ?edit: I will try to answer, more by intuition than by knowlege or experience.- measure fixture with unpowered DUT with instrument 1. Consider it to be N1. Repeat with same fixture and unpowered DUT for intrument 2 and get N2.- Nref1=Sqrt(N1^2-Nref1measured^2) where Nref1measured is from original post for powered DUT.- Nref2=Sqrt(N2^2-Nref2measured^2) where Nref2measured is from original post for powered DUT.- Compare Nref1 to Nref2 and if they match, you have confidence.

author: bgugi
author_rank: Contributor
timestamp: February 27, 2019, 01:12:14 pm
content: the math seems appropriate, but it rests on a few assumptions: the one that sticks out most is: "does the reference noise change with the measurand?" aka, can you expect your noise to be the same with both powered and unpowered dut?also of note is that your data doesn't seem very "clean:" one has a "jump," and the other appears to follow a linear trend. I would put effort into either identifying and removing, or at very least characterizing these trends (at the risk o fhttps://xkcd.com/2101/overfitting your data.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 27, 2019, 07:14:31 pm
content: Another issue is that statistics tend to assume uncorrelated processes... with reference, both may be exposed to the same temperature and humidity changes, which at least partially invalidates this assumption?