hybridfree/eevblog-posts huggingface dataset:
Replacement Thumbscrews for Leeds & Northrup 40XX series resistance standards - Page 1
Forum section: electronics / general

author: ptech1231
author_rank: Newbie
timestamp: September 10, 2023, 03:49:37 pm
content: Hi all,I recently picked up a set of 5 Leeds & Northrup 40XX series resistance standards (1 ohm to 10k ohm). 2 of them come with missing thumbscrews and I'm thinking of getting some replacements from online. What material thumbscrew should I get? I'm thinking of getting brass ones since that seems to be a popular choice for electrical terminals. If that's not a smart idea to use non original screws I can just share the 3 sets of screws that I have between the 5 standardsthanks in advance

author: alm
author_rank: Super Contributor
timestamp: September 10, 2023, 05:51:06 pm
content: I just share screws between resistors. I would think the original are chrome plated copper. Brass would be bad for thermal EMF. But I haven't checked.

author: donlisms
author_rank: Frequent Contributor
timestamp: September 13, 2023, 05:55:30 pm
content: I've been using plain (steel) 6-32 screws for the time being. The electrical connection is still wire-to-big-terminal, and I don't think having the other material holding things together will cause a problem.At first glance, any resistance in the steel is in parallel with the copper, and thus only makes the total resistance smaller.As to any Seebeck EMF floating through the screw, my theory is that it would be effectively shorted by perhaps micro-ohms of copper, in parallel with the screw.; I think of Seebeck as a fairly high impedance, low current sort of thing, not capable of the current required to see any voltage drop here, but I'm running on intuition, here.Perhaps the safer bet would be to get some of those (nearly) pure copper screws on eBay (not the plated ones, not the brass ones sold as "copper"!), and assume than any of these negligible effects are greatly diminished. And of course... how do you clean the internal thread?Otherwise, just trust the copper wire to massive (clean) (plated) copper post interface.Then, when we get the lathe, make some screws for *all* the resistors!I suspect the plating is silver.
Capacitif Differential Sensor Signal Amplifier - Page 1
Forum section: electronics / general

author: Emrelli
author_rank: Newbie
timestamp: September 13, 2023, 10:25:38 am
content: Hi Friends, i have a Capacitif Differential Sensor with 3 Pins (without any signal conditioner). How can i check the output signal on OScilloscope ? Is there any available amplifier module in market wich can help me connect the sensor to Oscilloscope ?Thanks for your help in advance...

author: MasterT
author_rank: Frequent Contributor
timestamp: September 13, 2023, 01:56:39 pm
content: https://www.ti.com/product/FDC2112?keyMatch=CAPACITANCE%20TO%20DIGITAL%20CONVERTER
Wavetek 4950 replacement cable - Page 1
Forum section: electronics / general

author: volvo_nut_v70
author_rank: Regular Contributor
timestamp: October 05, 2022, 02:59:51 am
content: I came across this company, GLKInst while looking at a cable for the Wavetek 4950. Anyone have any experience with any of their products?https://www.glkinst.com/cables/hp_cables.htm

author: CalMachine
author_rank: Frequent Contributor
timestamp: October 05, 2022, 03:24:35 pm
content: Quote from: volvo_nut_v70 on October 05, 2022, 02:59:51 amI haven't purchased anything from GLKInst, but I did make my own replacement cable. I think I might have an extra unused connector or 2. I had also put spades on the end instead of banana plugs.

author: yu2007
author_rank: Newbie
timestamp: September 02, 2023, 05:34:07 am
content: Hi brother , Could you share this plug ? thank you !

author: ap
author_rank: Frequent Contributor
timestamp: September 02, 2023, 07:53:22 am
content: Yes, would be nice for the records here to know the connector PN. I would think these are Fischer connectors. Also, the bananas are not low EMF as it looks, so spades or low EMF bananas are better..Dont have a 4950, but one never knows...
Z3801A help! - Page 1
Forum section: electronics / general

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: August 16, 2023, 11:01:18 pm
content: I have a Z3801A GPSDO that has been running fine for well over 10 years. It recently lost the lock indication and I can't get it back! I did look at the work around to fix the problem with the outer oven controller getting confused and it did not fix my problem. However it did show that the outer oven was not powering on, even if I supplied the workaround pull up described. With 0v supplied the oven is supposed to be off and with +5V supplied the oven should be on. With the 5V applies the oven voltage is zero. I did notice that the resistors R112 and R113 near P2 on the top board seem odd. R112 looks to be soldered very poorly and R113 is missing completely!Does anyone have an opened up unit or the top board loose so they can let me know what R112 and R113 are supposed to look like? The schematic I have does not show R113. Appreciate it and any advice. When the unit failed it did seem as it was still in lock and on frequency but with no lock indicator.Cheers,Corby

author: dietert1
author_rank: Super Contributor
timestamp: August 31, 2023, 11:30:36 am
content: In order to get the lock indicator the oven needs to run. I would try and repeat the procedure with disconnecting the control signal, installing the pullup and waiting for some time, whether the control signal comes on. Using that procedure the oven should turn on.I would test the GPS receiver first, looking at it's monitoring output. It needs to receive and track some satellites. Everything depends on a GPS lock.One could also check the frequency of the OCXO. The OCXO might require adjustment to bring its tuning range back to 10 MHz +/- some margin required for lock. Aging also affects electrolytic caps, especially those near hot ovens, resistors or semiconductors. This kind of maintainance is justified after 10 years. The unit will be much easier to fix than a rubidium standard.Regards, Dieter

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: September 05, 2023, 04:24:58 pm
content: Well I got it running!After a friend looked at his unit to determine the value of a resistor that was missing (I could tell someone had been working on the unit once I pulled the board!) and does not show in the schematic, replacing the smaller 5V Dc-DC convertor, and doing the pullup trick it's working fine now.The convertor I used was a 1.8Amp versus the 4.0Amp original but it runs just warm after a day of operation.HOORAY!Corby
Diff-amp 1GHz  - Page 1
Forum section: electronics / general

author: luky315
author_rank: Regular Contributor
timestamp: August 30, 2023, 09:52:39 pm
content: I am looking for an Differential Amplifier with the lowest possible noise to amplify a small diff. signal (50R impedance, 1mVpp, 10MHz - 1GHz) at least 5x (10x prefered)I found the LTC6401-20 which looks like a nice fit, but the noise is a bit to high (2.1nV/√Hz)Can someone suggest a low noise part for this job?

author: ycui7
author_rank: Contributor
timestamp: August 30, 2023, 10:28:41 pm
content: how abouthttps://www.ti.com/lit/ds/symlink/lmh5401.pdf

author: luky315
author_rank: Regular Contributor
timestamp: August 31, 2023, 10:35:50 am
content: Thanks! TI has some very interesting parts... LMH6554 looks also nice, it is slower, but with less noise.ISL55210 is also surprisingly good according to the datasheet, I have never used Intersil / Renesas analog parts, maybee it is worth a try

author: David Hess
author_rank: Super Contributor
timestamp: September 01, 2023, 03:36:26 pm
content: With only 1 millivolt peak-to-peak, you can use a two transistor differential amplifier with a pair of NPN RF transistors and no emitter series resistance. Noise is set by the tail current, so get a couple of medium power ones and operate them at higher current. Gain is proportional to tail current and collector load resistance. Noise will be lower and speed will be higher than any integrated solution.
u-blox M8T firmware FW 3.01 TIM 1.10 - Page 1
Forum section: electronics / general

author: wgoeo
author_rank: Contributor
timestamp: July 05, 2019, 10:02:59 am
content: I haven't seen this out there so here you go.MD5 is 9a999e9cf84f0b3a0a7ed0146d20e5cc as indicated in filename in the PDF.Rename .hex to .bin

author: Illusionist
author_rank: Regular Contributor
timestamp: July 05, 2019, 05:59:19 pm
content: Thank you, I've been looking for thisI must admit I was wary of flashing an image from a stranger on the 'net thoughThe MD5 matched the online docs from ublox though, so I gave it a shot on (cue Gollum)my preciousonly Neo-M8T, version 0-00. I can confirm it works.For those who try and wonder where the FIF file is that the updater wants, it's in the ublox u-centre installation. Just browse to there and find the flash xml file.ETA: My GPSDO-to-be also wishes to thank you...

author: charly724
author_rank: Newbie
timestamp: February 09, 2020, 11:42:57 am
content: Many Thanks...works also good for me. Update is very easy with the u-center via USB

author: rplabs
author_rank: Contributor
timestamp: August 23, 2023, 12:35:25 pm
content: I saw it in some u-Blox PDF files that there is a new release for TIM but FW revision stays the same.Flash FW 3.01 TIM 1.11There is also some documentation for M8 where it says FW 3.5x is also available. It is not clear if M8T is also covered by this release...Does anyone have more details about which models have FW 3.5x or what is TIM 1.11 ?
Symmetricom Syncserver S300/S350 firmware files or CF card images - Page 1
Forum section: electronics / general

author: maes
author_rank: Newbie
timestamp: August 11, 2023, 06:39:56 pm
content: I salvaged an OLD S350 that happens to have one of the first firmware versions released (2.03).Would anyone happen to have a newer firmware installation file (say in the 2.80 to 2.82 range) or be willing to share a CF image from a unit with a more recent firmware version?Since the S3xxs have been EOL for ages, firmwares are all behind a paywall / service contract now.EDIT:Found CF card images, thanks to another user here for posting them a few years ago!
Fluke 5200 AC Calibrator, Fan & Notes - Page 1
Forum section: electronics / general

author: tridac
author_rank: Regular Contributor
timestamp: August 07, 2023, 11:14:12 pm
content: Hi,Have been a lurker here for a while, but thought a fan mod for the Fluke 5200 and other notes might be of interest. Maybe tldr. It's an old design now, with schematics dated 1975, but accurate and stable when working. Problem is keeping them working, as there are issues with the power supply and also, the power amp seems a bit fragile, stretching the state of the 1970's art. A complex, but brilliant design for it's time. There are some 2 watt composition resistors on the power amp, which can go open circuit with heat and age. Easily replaced with metal oxide, but when they or transistors fail, can take out the power supply as well. Power amp now rebuilt, twice, helped by the sockets fitted for some of the transistors. Perhaps they expected it to fail.Some of power supply rails don't have current limiting, but instead, use low wattage sacrificial resistors that burn out on power amp fault, which can damage the pcb. Insufficient cooling for the psu area leads to a finger burning temperature on the 5 volt regulator. With age, thermal cycling, discolouring of the pcb causes failure of the copper track to substrate adhesive. Heat damaged pcb makes it difficult to replace parts without the tracks or through hole plating coming adrift. For the low value resistors, wirewrap pins fitted to standoff from the pcb, helps fix that, but some parts still running far too hot for reliability.For the fan, not a great deal of space, but the right psu card support plate looks ok. Used a tank cutter to cut out a hole, to allow air flow from the underside of the pcb, and the fan is spaced off the plate for more air input. Fan is an ex computer server ball bearing item. Power comes from the 5 volt regulator input, around 9.9 volts, so the 12 volt fan is underrun. Result, seems to get the job done, with the 5v regulator case at about 56 C now and the heatsink fins warm to the touch.There's an interesting 5 pole active filter on the reference supply. What looks like a double section version of the one used in the Fluke 335 voltage standard. The key thing is that the filter op amps are not in the reference signal path, so the reference isn't affected by op amp drift or offset. Can't find any reference on the web for this, but looks like a gyrator design of some sort. Just a handful of parts. May be worth digging into to adapt the idea for other reference applications.The 5200 is mostly working, frequency and voltages, with just a few frequency setting numbers in error. Seems more or less good right through the frequency range. At one volt, one KHz, it's just 10's of microvolts in error. Not bad for a fourty+ year old bit of kit. A real saga, too many hours, but just need to fix the remaining faults, then have a go at setting it up...
Rohde & Schwarz HMS-X for EMC testing - Page 1
Forum section: electronics / general

author: OwenH
author_rank: Contributor
timestamp: August 07, 2023, 07:14:28 am
content: Hi,I'm looking at a used Rohde & Schwarz HMS-X but haven't seen much talk on the forums about them. I need to setup a EMC pre compliance test rig and thought this might be a decent used spectrum analyser fort the job. The unit I'm looking at has the software upgrade for the TG, EMI options, 3ghz. Anyone have any insight into these?Thanks,Owen

author: artag
author_rank: Super Contributor
timestamp: August 07, 2023, 09:25:45 am
content: I have one of these. There's also a PC software suite that complements the EMI options on the spectrum analyser.You may also want the close-field probes, LISN, and/or a suitable antenna.Not sure I can offer an opinion of the kit as I don't have anything to compare it with, but it was intended for just this job.

author: OwenH
author_rank: Contributor
timestamp: August 07, 2023, 11:27:47 am
content: Would you say you are generally happy with it? Do you use yours for EMI testing? At the moment I only plan to use it for EMI testing.

author: artag
author_rank: Super Contributor
timestamp: August 07, 2023, 11:59:11 am
content: It has quite a high noise level compared with more fancy equipment and I find it relatively slow in use, but neither of these should be much of a disadvantage for EMI. I haven't used it myself for that yet, thjough I will need to soon - I use it for general jobs as I bought it fairly cheaply and it's handy to have - takes up little space and is acoustically quiet.
Valhalla 2703 Power Up Fault - Page 1
Forum section: electronics / general

author: tridac
author_rank: Regular Contributor
timestamp: August 04, 2023, 02:38:22 pm
content: Hi,Just brought home a 2703, after a 300+ mile round trip to collect it. Pretty clean inside, with just the right hand plastic handle extension broken off. On power up, it first comes up with "Hello" on the voltage display, then "3d" on the frequency display. Then "bad", voltage and "data", frequency. No diags in the manual, but any info as to what this means ?. Can copy the eprom, if anyone needs it, eprom label says: "2703 VD 1-10-89"...Thanks,Chris

author: alm
author_rank: Super Contributor
timestamp: August 04, 2023, 08:56:20 pm
content: There is some trouble shooting information in chapter 6 of themanual, but it indeed does not mention this error (or any errors on the display). Just a random guess, but maybe the NOVRAM (IC24/25 according to the manual) is corrupt?

author: tridac
author_rank: Regular Contributor
timestamp: August 05, 2023, 12:28:06 am
content: Thanks for that. Trouble shooting info is pretty dire, but could email Valhalla, as they must know what the codes mean. Can get new 2212 in ceramic for around 5ukp here, but they may need to be proprogrammed, assuming they don't auto set defaults in power up. 6809 system and probably programmed in asm. There is info on the memory map, so could disassemble it as a last resort..
The 3458a DEFKEY configuration thread - Page 1
Forum section: electronics / general

author: aronake
author_rank: Frequent Contributor
timestamp: August 21, 2023, 03:52:18 pm
content: Hi,To inspire each other on useful DEFKEY settings for 3458a suggest people post their typical standard settings here. Also feel free to share some special use case DEFKEY settings.For me:1 - Temp?2 - Cal?3 - NDIG 8 ; NPLC 1007 - MATH STAT8 - MATH SDEV9 - MATH OFF4 to 6 changes around as needed.

author: manupthehills
author_rank: Contributor
timestamp: August 21, 2023, 05:53:56 pm
content: 7: MATH NULL8: MATH OFF9: MATH STAT4: RMATH LOWER5: RMATH UPPER6: RMATH MEAN1: DISP ON2: RMATH NSAMP3: RMATH SDEV0: CALL disp_OFFSUB disp_OFFDISP OFF, ' 'SUBEND

author: mendip_discovery
author_rank: Super Contributor
timestamp: August 21, 2023, 05:56:46 pm
content: So far I have set keys for TEMP?, MATH NULL and DELAY 0.5I just state the settings needed in the procedure.I still have plenty to learn from this bit of kit.

author: scottbp
author_rank: Newbie
timestamp: August 23, 2023, 02:38:47 pm
content: You know you're a metrologist when you start defining the keys on your 3458A...The Fluke-ified HP3458A HFL had it's keys programmed thusly:0 - SETACV SYNC1 - LFILTER OFF2 - SCALE3 - RMATH LOWER4 - RMATH MEAN5 - RMATH SDEV6 - RMATH UPPER7 - MATH NULL8 - MATH STAT9 - MATH OFFI always defined mine as0 - MATH OFF1 - MATH NULL2 - MATH STAT3 - RMATH MEAN4 - MATH RMS5 - DELAY(And I even affixed small labels to the removable key definition templates that used to be supplied with 3458As).I never used the other functions enough to have to do a DEFKEY assignment...

author: IanJ
author_rank: Unknown
timestamp: August 24, 2023, 09:22:11 am
content: Here's mine:0. TEMP?1. ACAL DCV2. MATH NULL8. NDIG 8I have small labels (dymo) to indicate above the buttons.Ian.
Tinkering with the Tektronix DMM4050 - Page 1
Forum section: electronics / general

author: Daniel Wee
author_rank: Newbie
timestamp: January 04, 2017, 07:21:40 am
content: I'm tinkering with my DMM4050 (Tek re-rebranded Fluke 8846A) bench multimeter and was wondering if anyone has any firmware updates for the DMM4050. I know that Fluke has released some firmware updates for the 884X series but cannot seem to find any such firmwares for the DMM4040/50 series.I would really appreciate it if someone could point me to such a firmware file or even send me one.In the mean time, I had been looking at the Fluke 8846A firmware and made some interesting discoveries that I couldn't test myself. Basically, I looked at the image file for the firmware, mounted the file, extracted the shadow file and got the hash for root. In theory, this should allow someone to log into the Fluke 8846A over LAN - assuming you have that set up - via telnet.Normally you would telnet to port 3490 to get the meter interface but you can also telnet to the usual telnet port and get a Unix login (uClinux and busybox). You will be prompted for the user name and password. If someone would like to try this out - give me a reply here and I'll furnish the password I found.More importantly - anyone with the DMM4050 firmware? Thanks!

author: stevenp
author_rank: Newbie
timestamp: July 26, 2023, 02:15:52 pm
content: Hello there,I have a Fluke 8845A and can't seem to access it on TCP 3490 any more... I don't understand...it's configured to listen on 3490 but the connection fails.It used to work.If I telnet using standard TCP 23, I get a login prompt for user TEST1.Like this:TEST1 login: _I've tried all sorts of username/password combinations, but no go....Any ideas greatly appreciated.-sp
ADR1399 unobtanium ? - Page 1
Forum section: electronics / general

author: deepfryed
author_rank: Unknown
timestamp: July 17, 2023, 05:01:30 am
content: I wanted to build a small voltage transfer standard using ADR1399 (more as a learning exercise) and since the eval board seems affordable I thought I'd buy one but it seems the reference and eval board are both unobtanium. Anyone know if this is still being actively distributed ?

author: ycui@eml.cc
author_rank: Newbie
timestamp: July 17, 2023, 05:54:15 am
content: https://www.mouser.com/ProductDetail/Analog-Devices/ADR1399KEZ?qs=4ASt3YYao0UxLFsgv9r7yQ%3D%3D200+ in stock.

author: dietert1
author_rank: Super Contributor
timestamp: July 17, 2023, 05:58:25 am
content: mouser.com show a stock of 234 ADR1399KEZ SMD references at € 21,22 each. It's not an evaluation board, but in my opinion that board isn't special anyway.Regards, DieterEdit: They show an evaluation board image but it's the SMD part only. Why not use a LTZ1000? Boards/designs are "everywhere".

author: deepfryed
author_rank: Unknown
timestamp: July 17, 2023, 06:46:12 am
content: Thanks missed it, I'll wait a bit for the TO-46 package

author: Kleinstein
author_rank: Super Contributor
timestamp: July 17, 2023, 08:29:55 am
content: The availabilty for the TO46 version was pushed a bit in the past. So I would not bet on the current estimated date.The 2.5 weeks or so may still be worth waiting. To a large part the older LM399 can be used as a drop in replacement for first tests if really needed.

author: deepfryed
author_rank: Unknown
timestamp: July 17, 2023, 08:52:32 am
content: Quote from: Kleinstein on July 17, 2023, 08:29:55 ameeeks, I just ordered the TO-46 eval board. The customer support said they will have 7 in stock inAugustSeptember. Fingers crossed.

author: iMo
author_rank: Super Contributor
timestamp: July 17, 2023, 10:01:00 am
content: I wonder where all those TO-46 versions go.. Could it be somebody is hoarding them as a collectable wine?

author: r6502
author_rank: Regular Contributor
timestamp: July 17, 2023, 11:23:41 am
content: Quote from: iMo on July 17, 2023, 10:01:00 amSame to me, I asked ADI for samples about 2 month ago, but only LCC versions have been available at that time, so I got 5 LCC types ...

author: Kleinstein
author_rank: Super Contributor
timestamp: July 17, 2023, 12:32:49 pm
content: The delivery date pushed out bit by bit does not look like someone buying them all, but more like a small problem with the production. The TO46 case is not that common and may well use old machines.

author: deepfryed
author_rank: Unknown
timestamp: July 17, 2023, 01:54:23 pm
content: Quote from: r6502 on July 17, 2023, 11:23:41 amThe last time I asked ADI for samples, they said nope piss off :'(

author: deepfryed
author_rank: Unknown
timestamp: July 17, 2023, 01:56:53 pm
content: The only reason I'm interested in the TO46 package is to use a socket, so if I stuff up the design I can reuse the reference without destroying it. Also, I've never used a LCC package and wasn't sure if it needed special handling during reflow / soldering.
Passive Hydrogen Maser teardown! - Page 1
Forum section: electronics / general

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: October 19, 2021, 06:18:42 pm
content: Just added "update 5" tohttp://www.leapsecond.com/maser/It gives details on "digging down" to the cavity of the Maser.Lots of PIX!Cheers!Corby

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: November 16, 2021, 02:08:53 am
content: Just added "update 6" tohttp://www.leapsecond.com/maser/It gives details on removing and opening the cavity of the Maser.Lots of PIX!Here is the "eye candy" shot of the storage bulb!Cheers!Corby

author: dietert1
author_rank: Super Contributor
timestamp: November 16, 2021, 09:10:39 pm
content: Your interesting pictures reminded me of my last physics project. That was building an infrared optical frequency standard using a CO2 laser stabilized by a large OsO4 absorption cell, at 30 THz. The project was abandonded without completion after in 1989 the physics nobel prize went for the development of atomic traps.Funds got redirected to trap research. Guess there are results by now.Regards, Dieter

author: ch_scr
author_rank: Frequent Contributor
timestamp: November 17, 2021, 09:42:53 am
content: That video had nice glory shots of the laboratoryFor a more in depth technical presentation, I can recommend this from the same researcher,held at the BIPM conference regarding the redefinition of the SI constants (26th CGPM)

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: February 03, 2023, 11:19:55 pm
content: Find update 7 here:http://www.leapsecond.com/maser/UPDATE7.pdfCheers,Corby

author: notfaded1
author_rank: Frequent Contributor
timestamp: July 21, 2023, 12:33:48 pm
content: Sweet Corby... I missed this! It's been busy at work. Any recent updates?Bill

author: rubidium
author_rank: Regular Contributor
timestamp: July 21, 2023, 06:04:41 pm
content: Rather amazing work! You gotta have real stones to take on an effort like this!

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: July 21, 2023, 06:28:55 pm
content: After some work, including adding an oven to the vacuum chamber, I was able to take some measurements.Unfortunately For some reason I cannot get the cavity to tune properly at vacuum and at the correct temperature. Seems like the loaded cavity arrangement is very sensitive to changes. I did evaluate several new varactors and could get a proper range of tuning but the center frequency could not be obtained!Put the project to the side for a bit to regroup.Cheers,Corby
AT&T RFG-Rb Frequency adjustment - Page 1
Forum section: electronics / general

author: hedgehog
author_rank: Newbie
timestamp: June 18, 2023, 07:29:27 pm
content: I've just gotten an AT&T RFG-Rb unit, and for my purposes, the frequency is off; where "off" means that with the pot (I assume it's a pot) set almost fully CCW the 60 minute phase trend slope as compared to my GPSDO is nowhere near zero. When I put the pot completely against the CCW stop, the slope is just slightly in the other direction. But the adjustment is too touchy to be useful; like it's past the end of the adjustment area. Has anyone made a circuit "adjustment" to get the zero point nearer to halfway so this can be set properly?Bob - AE6RV

author: Raindog
author_rank: Contributor
timestamp: June 25, 2023, 03:20:30 am
content: I have one of these units but the C-Field adjustment is a 10-turn pot that is accessible through a hole in the top of the enclosure. There were several variants of this unit and some were equipped with different rubidium modules and associated control boards. If your unit has the larger Efratom module there should be a access hole in the module to adjust the C-Field, sounds like the pot your trying to adjust is a secondary adjustment with a dead spot.

author: hedgehog
author_rank: Newbie
timestamp: July 16, 2023, 05:48:42 am
content: Hi Raindog,Sorry I took so long to reply. No excuse. I finally took it out of its case to see what was interfering. A quick check on the pot indicated that it wasn't binding. So, I put it all back together and this time used the next smallest size of jewelers screwdriver. And it worked. I was able to get it adjusted very close to my GPSDO using the lissajous method.Bob
Weather sensor Vaisala PWD22 reboot. - Page 1
Forum section: electronics / general

author: zebu
author_rank: Newbie
timestamp: July 13, 2023, 08:43:02 pm
content: Hello ! Please tell me, has anyone repaired the Vaisala PWD22 weather sensor? Reloads randomly. Through different times. It can work for several hours, or it can reboot every minute. Replaced capacitances in the power supply. Tantalum capacitors on the board too. There is no stable ripple power supply. Replaced SDRAM. Still constantly chaotic reboots.
Bizzare issue with Picotest M3500-OPT01 - Page 1
Forum section: electronics / general

author: CosteC
author_rank: Regular Contributor
timestamp: July 05, 2023, 11:07:54 am
content: When Picotest M3500-OPT01( 10 inputs) scanning card inputs are connected to mains isolated 230 VAC 50 Hz, it sometimes does not measure - there is zero (or very low value) instead around 230 VAC. This does not happen at 120 VAC.It seems relays inside are not making contact or are not even driven. In some cases, one relay seem to be left in ON state while next channel is enabled. This leads to contact welding which is understandable.I am aware 230 VAC is beyond card official rating (125 VAC 100 kHz CAT II), yet within relay specs (NEC or NEXEM EA2-5TNJ depending on unit) which is rated for 250 VAC switching voltage, 1000 VDC, 1500 V surge. This is two coils latching type.I would expect contact wear, too high crosstalk, even arc-over but incorrect operation of relay control.While system will use different DMM, I would like to understand what root-cause may be. Any ideas?

author: Mickle T.
author_rank: Frequent Contributor
timestamp: July 05, 2023, 12:44:59 pm
content: What firmware version is in your device?

author: CosteC
author_rank: Regular Contributor
timestamp: July 05, 2023, 12:51:13 pm
content: SYS VER. 03.41-01-04Bit unsure how to relates to firmware version V3.40 available here:https://www.picotest.com/support.html
Modeling/designing a quasi-peak (digital) detector - Page 1
Forum section: electronics / general

author: MPM
author_rank: Newbie
timestamp: July 01, 2023, 08:00:08 pm
content: There is a need and desire to try to simulate a digital quasi-peak detector. In the Internet I found very little information (mostly articles), which, moreover, implies experience and knowledge. Many textbooks contain only the definition of quasi-peak detector and its circuit. Maybe someone can suggest modern literature on this topic? Or maybe there are ready-made models on the Internet (Simulink, although I have not found any:))?
Does anyone recognize this? - Page 1
Forum section: electronics / general

author: rhb
author_rank: Super Contributor
timestamp: June 29, 2023, 10:53:48 pm
content: It's a 1 k Ohm precision resistor ladder. Other than the resistor sizes there are no markings.Reg

author: Martian Tech
author_rank: Regular Contributor
timestamp: June 30, 2023, 02:22:40 am
content: Leeds & Northrup 4254?

author: rhb
author_rank: Super Contributor
timestamp: June 30, 2023, 02:40:43 am
content: Highly unlikely. I've got an L&N version, though rather larger.
Fluke 732A - What measurements/math should I do for the first 24 hours running? - Page 1
Forum section: electronics / general

author: Tony_G
author_rank: Super Contributor
timestamp: June 23, 2023, 04:08:38 pm
content: Hey All,I have my recently acquired and battery-updated 732A running and I'm capturing measurements from the 1V output on my 3458A.What key measurements or math operations should I be taking on the 732A or the CSV from WinGPIB to get an idea on how the unit is settling in?I'm seeing values ranging from 0.99999856 to 0.99999886 over the last 15 minutes or so but really that doesn't mean much to me as I'm officially a 732A NOOB.Any advice is appreciated.Thanks,TonyG

author: Dr. Frank
author_rank: Super Contributor
timestamp: June 23, 2023, 04:31:30 pm
content: Monitor the 10V instead, because that range / value is the most stable on both instrumentsSet 3458A to NPLC 50 .. 100, AZ on. Make an ACAL after 6h warm-up period.Place the whole setup in a stable temperature environment, i.e. +/- 0.2.. 0.5°C at most over 24hUse a monitoring program, which is able to frequently monitor (e.g. each 100 samples) the 3458As internal temperature TEMP?Monitor over 24h, date, time, 732A value and TEMP?That way you can get an idea of the initial stabilization of the 732A, its 24h stability (if that of the 3458A is already known, and its internal T.C.), and the common noise.Plot 732A value and TEMP? over time.See examples on my 24h stability measurements on references in the LTZ1000 Super Duper Thread.Frank

author: alm
author_rank: Super Contributor
timestamp: June 23, 2023, 08:14:06 pm
content: In addition to what Dr. Frank writes, I'd also monitor the 732A's oven temp thermistor's resistance for a while. Doesn't need a super accurate DMM, any good 4.5+ digit dmm should work. No need for a 3458A. The actual value doesn't matter much, but it should be stable over time within probably around 1% (0.25°C).

author: Tony_G
author_rank: Super Contributor
timestamp: June 23, 2023, 09:19:34 pm
content: Thank you, Dr. Frank & ALM,I took a look at the 132-page long LTZ1000 thread but I do have one quick question - Do you have a preferred monitoring program? I can write my own but I thought I might ask before I kick off and do so.Thanks,TonyG

author: alm
author_rank: Super Contributor
timestamp: June 23, 2023, 09:56:54 pm
content: Quote from: Tony_G on June 23, 2023, 09:19:34 pmI'm usingmy own Python scriptswhich are probably not super accessible, but if you use Windows then I thinkWinGPIBis worth looking at.

author: Dr. Frank
author_rank: Super Contributor
timestamp: June 24, 2023, 09:35:36 am
content: I also have my own stone old turbo pascal spaghetti codeFrank
Wavetek 1281 - Page 1
Forum section: electronics / general

author: Kenny Powers
author_rank: Contributor
timestamp: June 21, 2023, 07:03:32 pm
content: Hello,When measuring 1000V DC on my 1281 I find the meter seems to drift alot downward starting for e.g 1000.0056 after 5min 1000.0011 and it keeps going down, how long would you guys generally wait for stability to take a reading?Would anyone have the calibration procedure/ set up handy as it may explain clearer.I took this from the 3458a manual where is says wait 5min before taking a reading at 100mV DCDC voltage function gain testDMM.4 Set the range of the DMM to 100 mV. Wait five minutes for the DMM tothermally stabilize.KP

author: mendip_discovery
author_rank: Super Contributor
timestamp: June 21, 2023, 08:11:14 pm
content: Take a look over at TiN's xdevs.com site as there are a ton of manuals there.I think you are catching on other issues as measuring at 1kV you will be causing stuff to warm up etc. Plus the stability of the source.

author: Testtech
author_rank: Regular Contributor
timestamp: June 23, 2023, 11:23:29 pm
content: I had a 1281 with a drifty 1000 VDC attenuator resistor. The self heating at 1KV caused the 100K ohm resistor to drift quite noticeably.
HX711 scale amplifier where to buy / experience? - Page 1
Forum section: electronics / general

author: r6502
author_rank: Regular Contributor
timestamp: July 24, 2023, 12:20:59 pm
content: Hello all,we have to evaluate 4 load cells at the same time, and found the HX711 chip, that has an internal reference, regulator for the load cell supply and can evaluate 2 load cells. Very interesting chip.Has someone experience with this chip, and where to buy the chip itself - i can only find breakout boards with this chip, not the chip.Any info is welcome.Thanks Guido

author: Kean
author_rank: Unknown
timestamp: July 24, 2023, 01:38:14 pm
content: I've worked with the HX711 in the past, but I found it a bit annoying to work with. If you don't get the read timing just right you can get spurious readings.Apart from breakout PCBs and modules (i.e. Sparkfun, M5Stack - both available on Digikey) you can source the ICs from many random sellers on AliExpress.If you are going to want a commercial relationship, then contact Avia Semiconductor directly.http://en.aviaic.com/detail/730856.htmlThere is a good Arduino library for the HX711 and lots of helpful info athttps://github.com/bogde/HX711/Personally, I switched to the Texas Instruments ADS1232 (back in 2015) and it has been a great solution for my wildlife monitoring systems. I use this mostly for dynamic weighing of penguins, but also some other projects.
The HP10830A used as a DMTD system - Page 1
Forum section: electronics / general

author: 5065AGuru
author_rank: Frequent Contributor
timestamp: June 12, 2023, 09:50:06 pm
content: Hi!The HP 10830A was used in the HP5390A frequency stability analyzer system sold from 1977 to 1984. The HP10830A was never listed separately.I've always wanted to play with them and eventually found a pair!After a quick checkout I installed a small board internal to each unit to convert the low level bipolar TIC output to a 5uS TTL pulse. I also installed a different value capacitor to give me a 2.5Hz BW selection as the original units lowest BW setting way 25Hz. After a quick test against a couple oscillators it looked promising.I then put together a unit that has isolation amps for the LO and RF channels and a 5Mhz LO oscillator to provide a 1Hz offset. Almost all my testing is done at 5MHz but I also installed a doubler to give me a 10MHz LO if required. Also included was the ProTIC TIC counter and FTDI friend USB interface. With the pair of 10830A, the amplifier/LO chassis, and a laptop I have a nice DMTD system!After getting it all together I ran some ADEV plotsFirst one, some Quartz against Quartz.Next A 5065A vs a 5065A.Then a 5065A vs a 5061B.And finally a 5065A vs a passive Maser.All these look quite nice!The last picture thumbnail is wrong but if you click on it you get a PIX of the assembled isolation/LO unit!Cheers,Corby
HP7562A Log voltmeter/converter service manual? - Page 1
Forum section: electronics / general

author: dobsonr741
author_rank: Frequent Contributor
timestamp: June 11, 2023, 04:59:49 pm
content: I just got an HP7562A, needing repair, and wondering if you can point me to a service manual with schematics?

author: factory
author_rank: Super Contributor
timestamp: June 11, 2023, 05:48:31 pm
content: There is an original manual on ePay;https://www.ebay.com/itm/115826337946Or the pdf version on CD from Artek on ePay (don't use their website ATM, it has problems, see quote below);https://www.ebay.com/itm/391789561296No free downloads as far as I know for this one.Quote from: The Doktor on June 03, 2023, 06:12:40 pmDavid
General Dynamics R2670B Programming Manual Anybody have a copy????? - Page 1
Forum section: electronics / general

author: rcard53762
author_rank: Newbie
timestamp: April 29, 2023, 03:08:53 pm
content: General Dynamics R2670B Programming Manual Anybody have a copy??These are the same as the Motorola R2600 Units.They are not made anymore and I cannot find a programmers manual.Thanks

author: IFMATOS
author_rank: Newbie
timestamp: May 01, 2023, 01:49:31 am
content: Hi.I got two of those equipment form a Bit by old Motorola Lab. Onde is working fine and the second shows the noise floor way on the Top of display. Im having alots of problems to find which version it was upgraded. The one that has a sticker shows 2660C and the other has exactly the same screen but has nothing about the version.. B, C,D, etc.. I would love to find a way to update the software to the last possible version.Did you find anything ?Thanks

author: rcard53762
author_rank: Newbie
timestamp: May 10, 2023, 10:04:19 pm
content: NO I got a lot of views but no answers for a programming manual. I thought someone would have one.OH well good luck on yours.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: May 11, 2023, 01:47:59 pm
content: Maybe try this grouphttps://mailman.qth.net/mailman/listinfo/premium-rx

author: rcard53762
author_rank: Newbie
timestamp: May 30, 2023, 08:05:35 pm
content: Found it its on Groups.IO.MotorolaCSA group if anybody else is looking for it.

author: IFMATOS
author_rank: Newbie
timestamp: July 17, 2023, 11:04:47 pm
content: 1.000.000 THANKS..
Symmetricom XLi + HD8736 - Page 1
Forum section: electronics / general

author: comsec22
author_rank: Contributor
timestamp: June 02, 2023, 11:06:36 am
content: After upgrade with new HD8736, reception of SV is astonishing..So not anymore issue due to WNRO.. UNLOCK alarms..But timing is always affect of plus 18 seconds.I use a TTL to USB converter, to monitor data from the HD (TP5) using Trimble Studio.When i select LOCAL time on the Symmetricom, I get same timing of T.S.When time i set to time on UTC (Z) , an offset of + 18 second is add.Using F67 menu to manage Leap Second, no way to avoid it. Actually is set to -18/-37 NONE.In a few words, what I do really need is to have UTC = LOCAL -18 seconds.On the TRAK 9000S leap second is set to NONE, and I have the right time..Right UTC time also on TrueTime XL-Ak : all of them use the same GPS antenna through a GPS NETWORKING Inc.'s splitter.Also a DCF77 clock (Auriol) give the right time :'(
115v to 400hz variac to test Polarity brake coil - Page 1
Forum section: electronics / general

author: angelG
author_rank: Newbie
timestamp: May 30, 2023, 02:33:30 pm
content: HelloWe need to test polarity in a brake coil assembly, need provided a 115v to 400Hz signal.any idea about which Setup & equipment shall we need.

author: HalFoster
author_rank: Frequent Contributor
timestamp: May 30, 2023, 04:35:26 pm
content: Search for "AC Power Source" on epay - many models from Elgar, California Instruments etc. Be prepared to pay a lot for shipping though - there is a lot of iron in them.Hal

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 30, 2023, 05:42:41 pm
content: How much power ?For up to a few hundred watts, an audio amplifier coupled to a transformer may be a good option.

author: angelG
author_rank: Newbie
timestamp: May 30, 2023, 09:04:24 pm
content: low power around 45W

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 30, 2023, 09:14:06 pm
content: Easy enough then, 400hz sinewave into a 100w audio amp, and a reversed mains transformer on the output

author: Psi
author_rank: Super Contributor
timestamp: May 30, 2023, 11:04:10 pm
content: Yep, exactly what Mike said.The mains transformer wont be super happy with 400hz instead of 50hz but should be fine for the short time needed to test your device.Just keep an eye on it's temperature, or pick a larger one than necessary power wise.Transformers can be grossly over-driven if you only need to use them for 20 seconds at a time, or whatever.If building a more long-term system you can just attach a normally connected thermal switch to the top of the transformer metal core and use that to cut the power if it gets too hot from too much use. 55degC or so.
AT&T - Efratom RFG-RB Rubidium Frequency Standard  - Page 1
Forum section: electronics / general

author: Raindog
author_rank: Contributor
timestamp: May 23, 2023, 03:07:15 am
content: Hello all,Anyone out here know where I can get documentation on one of these Rubidium standards? Information is pretty sparse on these units, mostly what I'm looking for is which Efratom rubidium module is likely to be installed in this unit.Thanks.

author: 807
author_rank: Frequent Contributor
timestamp: May 24, 2023, 03:43:07 pm
content: Mine has an Efratom Rb Part no. 102100-003.The front panel appears to be the same as the Lucent badged unit, but the insides are different. Mine has 2 PCB's, the Lucent has only 1.Link to Lucent model...https://www.makarov.ca/rubidium.htmAttachments show my unit.

author: Raindog
author_rank: Contributor
timestamp: May 25, 2023, 01:55:10 am
content: Thanks for the reply. The unit I purchased is identical to the one in the link but says AT&T in place of the Lucent badge. I have been unable to find any users or operation manuals on this unit, the only info I can find just refers to the units ability to ad a slave unit and or a GPS receiver. I asked the seller if they might be able to provide any additional information on the unit but have yet to receive a response. I am currently waiting on shipping and wanted to get as much information as I could.

author: 807
author_rank: Frequent Contributor
timestamp: May 25, 2023, 11:56:27 am
content: That's interesting. I was assuming that all the AT&T were the same, but obviously not. As you have discovered, info on either variant of these units is hard to come by. At least Ivan has provided you with a circuit diagram for your version.I'll have to fire mine up again & check the quality of all of the outputs, as my circuit is different to the one in the article. I dont have the second MMIC in the 15MHz output (just U3, a MAR-3). Also, my 10MHz output goes straight to U1, pin 16 (via W1), with no resistor in the path.Be interesting to probe the RF output of the Rb itself, before being processed by the microcontroller.Bought mine 15 years ago for around $150 from China.

author: Raindog
author_rank: Contributor
timestamp: May 27, 2023, 04:18:38 pm
content: As a point of clarification mine is the two board version, there is a access hole on the top to adjust the C-Field if needed.
Load life stability of enameled copper wire used for TC adjustment? - Page 1
Forum section: electronics / general

author: aronake
author_rank: Frequent Contributor
timestamp: June 05, 2023, 01:16:50 pm
content: I well know method of adjusting TC is to add some copper wire with high TC.Have anyone done experiments, seen any information or have views on what "load life stability" these coper wires may have? the trade off is to reduce TC with 1 ppm / K, but introducing X ppm / year in drift this may not be a good idea, but would depend on application.There have been cases where i have added 1 ohm to a 10K resistor to get it compensated. So even if the copper wire resistance would move 1% total change would be very small, but may add to the load life stability of the base resistor.When I have done these compensators I have covered them in a thin layer of epoxy to reduce future air impact. Does that sound like a good or a bad idea? If they have some load life stability issues, and other ideas how to best treat them?

author: dietert1
author_rank: Super Contributor
timestamp: June 05, 2023, 06:14:33 pm
content: Copper forms oxide layers that become a protector after some time. Remember that copper is/was used on the roof. One could do an accelerated aging test to see how resistance is affected by the formation of oxide. It might depend on wire thickness (total amount of copper used).Using transformer wire coated for isolation should be a good method. Don't know whether epoxy can harm the coating.Regards, DIeter

author: aronake
author_rank: Frequent Contributor
timestamp: June 07, 2023, 01:23:48 pm
content: Quote from: dietert1 on June 05, 2023, 06:14:33 pmThis is very much in line with my thinking. But at the same time, quite decent resistors can have quite some load life drift, which should still be much less than a good old copper wire in air (save for oxidation layer once that is formed and the coating).

author: WattsThat
author_rank: Frequent Contributor
timestamp: June 07, 2023, 01:47:44 pm
content: There is negligible dissipation in the 1 ohm resistor as it is the ratio of the two resistors. If you have 100mW in the 10k, you’ll have 10uW in the 1 ohm. Do you think that will drift due to heating?

author: donlisms
author_rank: Frequent Contributor
timestamp: June 08, 2023, 05:56:36 pm
content: Furthermore, a drift of 1% has an effective drift of .01 / 10k = 1ppm.Just by intuition, it seems unlikely to have a drift of 1%.