hybridfree/eevblog-posts huggingface dataset:
HP 4328A MilliOhmmeter - an easy restore back into service - Page 1
Forum section: electronics / testgear

author: precaud
author_rank: Frequent Contributor
timestamp: February 16, 2018, 08:20:58 pm
content: Some of you may remember in 2002-03 in the runup to the Iraq war, there was a huge dumping of test equipment after the Pentagon gave the big DOD contractors the green light to upgrade their equipment cost-no-object in preparation for it. This unit was one of numerous pieces I bought at that time for next to nothing, found it needed a special cable, and set aside. And forgot about... until last week.First step was to make a cable so I can test it. There are already a couple good articles on the 4328A, this one was particularly helpful with details on making the cable:http://www.qsl.net/n9zia/hp4328a/index.htmlDigikey still stocks the Hirose connector. There are cautions in the manual about the maximum resistance AND length of the cable if you want to use the meter on the 1mOhm range. The cable's resistance range is given as 2mOhm to 20mOhm per lead. I interpreted "length" as referring to a maximum inductance, though they never gave figures for it. The qsl article didn't address this aspect and used 22ga wire for their cable, which would easily exceed the maximum R limit on an 18-inch cable. I decided to make a cable using multiple conductors in parallel per lead to lower the inductance. I found an old video cable that has 9 pairs with fine-gauge wire and braided shield. It was nice and slinky too. Giving each pin 4 wires, the R for the 18" run was 21mOhm, just above 20mOhm limit. I didn't measure the inductance.First test showed the unit worked but readings were all over the place, the range switch was badly intermittent. I doused the three switch decks with DeOxIt and worked the switch for a minute or so, and then sprayed it down with contact cleaner and air-dried it. Voila. That's all it took. Cal looked at tad high on all ranges so I went through the cal procedures which are very simple.Comparing various resistors from 3mOhm to 100 Ohms, against a Valhalla 4716 and my HP 4276A used in Z/phase mode, the little Kelvin clips are a bit fiddly to use but once good contact is made, the 4328A gave identical readings as other the two meters. Not bad for a 40-year-old design.Of great interest to me was to see if or how well it performed on the 1 milliOhm range with these low-inductance cables. I compared readings using three of the shorting "bars" that I use to short various fixtures or probes (see the 3rd pic). The next three pics shows the 4328A measuring them, easily showing the difference between them. Taking care to put the Kelvin clips in the same location for each, the measurements agree really well with the Valhalla.I don't care for these little Kelvin clips. I like the size (about 2" long) but the jaws are barely textured and don't grab onto the DUT very well. Any suggestions on better small Kelvin clips?This meter is a really welcome addition to the test bench.
Missing bit values in GW Instek GDS-1054B - Page 1
Forum section: electronics / testgear

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: February 15, 2018, 01:24:37 am
content: I just purchased a new Instek GDS-1054B and could immediately see that ADC is missing some bit values. Here are screen shots with a triangular input wave, one can see gaps in the data lines. But its not just a graphical problem. If I save the data and then do a histogram of the bit values, one can clearly see that certain values are missing. The period is roughly every 4th bin if acquiring from one channel and every 8th bin if acquiring from 2 channels. It does not depend on the sample rate or which channel is being used. When acquiring from all 4 channels, the gaps are less obvious, but still seem to appear under certain conditions.I have contacted GW Instek support but have not heard from them yet. Unless its a peculiar hardware defect in my scope (which is hard to imagine since the output of the ADC is serial), it seems to be a pretty glaring flaw in their firmware.

author: rf-loop
author_rank: Super Contributor
timestamp: February 15, 2018, 05:56:29 am
content: Quote from: maxwell3e10 on February 15, 2018, 01:24:37 amReally(?), what is this 1GSa/s ADC what have serial mode output? This interface must be fun..Back to ground surfaceAs far as I know there is just one ADC chip and it is Hittite Had1511.

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: February 15, 2018, 04:55:51 pm
content: Quote from: rf-loop on February 15, 2018, 05:56:29 amDuh! That's what I get for reading in the datasheet "Serial LVDS/RSDS Output" and not thinking any further.Anyway, I think I figured out the problem with the firmware. They must be doing some data scaling using 8-bit numbers. Here is a histogram if one takes an integer, multiplies it by 1.3 and makes it integer again. Looks exactly the same as the scope data.I haven't seen this problem in other scopes I checked. They must apply an overall vertical calibration correction without forcing the result to be an 8-bit number.
MHS-5200A DDS Generator Frequency Calibration - Page 1
Forum section: electronics / testgear

author: tardsat
author_rank: Newbie
timestamp: February 06, 2018, 04:32:56 pm
content: I have replaced the reference oscillator in my MHS-5200A with a stable 16.000000 MHz TCXO. Got it dialed in to find what someone else has discovered...there must be a factory calibration value stored in memory somewhere.Ref Osc. = 16.000000 MHzChannel 2 Setting to achieve 0 beat with 10MHz WWV = 10.001131 KHzFrequency Counter readout (Ch 2 loop) = 10.001207 MHzI tried dropping the frequency of the TCXO down to see if I could correct it but of course it doesn't have that much range.Has anyone discovered a USB/serial command, front panel key combination, or internal jumper that allows you to adjust the "factory" calibration?I e-mailed the factory (in English) the week before Chinese New Year and asked them how to do it. I will be holding my breath until they reply...I will post a picture of the mod later, involved removing the XTAL and 2 associated caps, and tapping 3.3V off another cap to feed the TCXO I purchased.

author: tardsat
author_rank: Newbie
timestamp: February 15, 2018, 09:16:06 pm
content: OK, I figured it out.Below is a picture of the connections I made to connect the 16.000000MHz TCXO.But here is the BIG news...with the power off, press and hold the SET button while powering on the MHS-5200A. WALA! A calibration menu appears. I haven't had time to write up the details, but for me a 5000 frequency number gives the best result, although I don't think the ratio is able to directly work with 16.0000000MHz, so you may want to bend your reference a little to get exactly on. Of course, I am into measuring frequency within .1Hz at 20MHz, so you may not need to be that exact. Maybe someone else can play around and help me out. There is also voltage level settings in the calibration menu.Bad news for the frequency counter...displays 10.000074 on the self test when fed with the 10.0000000, regardless of cal setting, but that's still really useful. I think that's in the coding, and it is consistent (1.000007MHz for 1.000000MHz in).If you hold the top left button (CH1/2) while powering on I think it factory resets.Just get a 3.3V 16.000000MHz TCXO and connect the 3 leads as show below. I don't have a picture of the "after" with me here at work. Once I was able to "un-calibrate" the factory error correction I have a dandy little agile generator, and it has great resolution and accuracy in the area below 1 MHz! It stays within 1 Hz at 10MHz through a range of room temperatures. I use it to verify my GPSDO and other references aren't wobbling, and also to drive other radios reference crystals.
HP/Agilent E4403B option board - Page 1
Forum section: electronics / testgear

author: wayne p
author_rank: Newbie
timestamp: February 15, 2018, 08:17:25 pm
content: HiI am trying to find a tracking generator option assembly (opt 1DN) and also a IF/Sweep port option assembly (opt A4J) for a HP/Agilent 4403B Spectrum Analyzer....Assistance locating these parts would be greatly appreciated.Wayne
Reliable clamp meter with good sampling rate.  - Page 1
Forum section: electronics / testgear

author: anishkgt
author_rank: Frequent Contributor
timestamp: February 14, 2018, 06:04:01 pm
content: Hi all,Am looking for a clamp meter to measure ac/dc current with inrush current feature but I can’t find anything that can measure less than 1ms.None seem to have these mentioned in the manual or the box itself. Would anyone know any ?Www.Georgehobby.wordpress.comEquipments: DSO104z, Hakko FX888D, Brymen BM869s
Re a function generator for audio, - Page 1
Forum section: electronics / testgear

author: Hextejas
author_rank: Frequent Contributor
timestamp: February 14, 2018, 03:34:46 pm
content: Are square waves and triangle waves important in the generator if I am going to use it to help tune my audio system ?The reason that I ask is that I am looking around for a function generator kit so I can build one.One kit that I saw said that it could produce a sine wave and a square wave.So, is it important to have a triangle wave ?And as an aside, in my noob ness, I thought that only sine waves would be useful.Thanks.

author: porker1972
author_rank: Contributor
timestamp: February 14, 2018, 04:20:38 pm
content: Bose demonstrated that nobody can hear the difference between a 10kHz sine, square and triangle wave back in the 1950s as the harmonics are beyond human audio perception.There really is no need to put a complex waveform in an audio circuit to test it. Standard R&D and production test is a 1kHz sine wave, nice and clean. You can hear and see on your scope if anything is wrong with that. You may want to sweep the frequency from 10Hz to 20kHz (makes a Star Trek-like zap gun sound) to go over the normal audio range, but 10kHz will be fine - the old analogue sig gens are just as useful as anything expensive like a DDS generator.You can build your own from a voltage to frequency converter IC, using a simple pot divider to vary Vin which changes Fout. There are loads of example circuits for this. So long as you have a scope, you can measure the frequency output so don't need to add a frequency counter - display (original signal sources were actually these two instruments combined!)

author: David Hess
author_rank: Super Contributor
timestamp: February 14, 2018, 04:43:58 pm
content: The different waves all have their uses depending on the test.Square waves are used for impulse response testing which essentially shows gain and phase response all in one shot. This is used to adjust the transient response of the amplifier.Sine waves are used for distortion testing although most function generators have more distortion than a good audio amplifier so this is of limited use.Triangle waves are useful for revealing crossover distortion and limiting or clipping. They may also be used to sweep the operating point of a circuit.

author: Lightages
author_rank: Unknown
timestamp: February 14, 2018, 05:45:51 pm
content: If all you want to do is inject a signal to test if there is an output or to adjust levels then making a simple op amp oscillator is all you need to do. If you want to analyze frequency response, phase shift, distortion, etc, then you have some really expensive options or some very inexpensive options.The least expensive is to use your computer as the sound source and the measurement device. There are some things to be cautious about so as to not damage your computer. Have a look at:http://www.sillanumsoft.org/orhttp://audio.rightmark.org/index_new.shtmlThere are many others too. There is also the option of buying hardware but the free software is more than adequate.
Why does my HP 5334B frequency counter display all 9's? - Page 1
Forum section: electronics / testgear

author: aa7ae
author_rank: Contributor
timestamp: February 14, 2018, 06:51:56 am
content: I have an interesting phenomena here that I don't understand. I've got an HP 5334B frequency counter and a couple of signal generators; an HP 8657B and an HP 8648C. They're all tied to the same 10 Mhz frequency standard, which is a GPSDO made by James Miller, G3RUH. Whenever I plug my signal generators into the frequency counter, the counter always seems to want to display 9's in the least significant digits. If I enter 15 Mhz, I get 14.999999 in the display. If I change frequency to something like 10.123456, the counter will display 10.1234559. Is my frequency counter out of adjustment or something?

author: Tony_G
author_rank: Super Contributor
timestamp: February 14, 2018, 07:42:54 am
content: It's fairly typical to have a counter flicker by +/- 1 count as each gate period could contain 1 more or 1 less signal edge. Try setting it up using the 100 gate average and see what happens.

author: aa7ae
author_rank: Contributor
timestamp: February 14, 2018, 04:07:44 pm
content: Setting up a 100 gate average severely slows down my update rate, but I still have all 9's in the digits past the decimal point. I also increased my gate time to improve the update on the average. The counter really isn't flickering that much. Being that it's only off by say .1 Hz or 1 Hz isn't really an issue either since I don't necessarily need that level of precision. But when you're expecting to see 15.000000 on the dot and instead get 14.999999, it's like staring at a picture hanging on the wall that's slightly tilted. You become OCD and want to fix it!

author: tggzzz
author_rank: Super Contributor
timestamp: February 14, 2018, 05:17:23 pm
content: Quote from: aa7ae on February 14, 2018, 06:51:56 amFind your instrument's specification, and take careful note of the tolerances. Then add the tolerance to the measured value, and compare with (ehat you believe to be) the input.Do the same with whatever is producing the input.
Question: Dual tone from a fy3200s - Page 1
Forum section: electronics / testgear

author: innkeeper
author_rank: Unknown
timestamp: February 14, 2018, 05:15:48 pm
content: So i want to generate a dual tone from a fy3200SI think I can just use the two channels and use either a star or delta resistive splitter/combiner to achieve it.i'm not so sure what the harmonics would look like though.what id rather do is create an arbitrary waveform with the two tones, but have no idea how to accomplish that.not that i don't know how to use the tool, but i don't know how to generate the right data to plug in.any thoughts on either method or anything i have thought of?
Wavetek Meterman HD110B very slow to read voltage - Page 1
Forum section: electronics / testgear

author: N0NB
author_rank: Contributor
timestamp: February 13, 2018, 04:58:38 pm
content: I have a Wavetek Meterman HD110B DMM that I won at a hamfest in late 2003 that for some time has been very slow to read DC or AC voltage. I replaced the 9V battery with a fresh one and found no difference. If it has sat for a time (on or off) and I try to read 13.8VDC it will take a minute to a minute and a half before it gets to the reading and sort of stabilizes. Looking at a wall socket it takes about 15 seconds to reach 120VAC and then the reading is never stable. It acts like it is measuring a large capacitor charging.Since I have no money in the thing, I'm not inclined to spend a pile of cash fixing it. Any quick tips of what I might look for are appreciated, though.

author: N0NB
author_rank: Contributor
timestamp: February 13, 2018, 10:22:36 pm
content: Got some new batteries and it seems to be working as it should now. The "fresh" one I put in this morning measures around 8.19V and the original one I took out this morning measures 9.24V. Another out of the new pack measures 9.76V.The lesson is that when it gets wonky, change the battery.

author: soundtec
author_rank: Regular Contributor
timestamp: February 14, 2018, 01:59:31 am
content: I have a wavetek Dmm nearly 20 years at this stage ,still as good as new , only thing Ive had to do to it over the years is a gentle polish and re-tensioning of the springs and contacts of the rotary switch . The buzzer does sound continiously if theres any dampness or condensation gets in ,but I think thats a feature rather than a fault . My brand new Uni-T 171b just arrived today ,so just getting around to exploring all the new functions that has , the test leads that came with it are dissapointing though ,plasticy wire insulation with memory, not supple silicon rubber like it should be . I wont be getting rid of the wavetek though ,been through good times and bad with it and its never let me down , I wonder how the Uni-T will be in 20 years from now.
Problem with Siglent SDM3055 Multimeter - Page 1
Forum section: electronics / testgear

author: mrt6644
author_rank: Contributor
timestamp: February 11, 2018, 10:01:47 pm
content: I have a Siglent 5 digit bench meter and haven't used it for a while.Today when I tried to start it up, the splash screen comes on but stays there.It never moves past the splash screen and doesn't function.Anyone have this issue?Are there are any key combos for starting up to get in diagnostic mode?Its pretty darn new so not sure why its not working.

author: tautech
author_rank: Super Contributor
timestamp: February 11, 2018, 10:59:54 pm
content: Quote from: mrt6644 on February 11, 2018, 10:01:47 pmDo you know if it has the latest firmware V1.01.01.19 installed ? Came out Sept 17.In it Siglent added a USB recovery function.https://www.eevblog.com/forum/testgear/siglent-new-bench-dmm-sdm3055/msg1291940/#msg1291940Just how to get hold of the files right at the moment I'm not sure as the factory has gone on hols until 23 Feb.Maybe by chance a member has the files and spots your thread.Maybe the Ohio branch has it.https://www.siglentamerica.com/contact-us/I can't remember if there's a button sequence to get past the boot freeze but if there is it should be mentioned in this thread:https://www.eevblog.com/forum/testgear/siglent-new-bench-dmm-sdm3055/

author: mrt6644
author_rank: Contributor
timestamp: February 11, 2018, 11:30:34 pm
content: Thank you for your reply and info.I scanned that thread and didn't see any boot key function.I sent an email to the site you listed.Not sure what could have happened.I never tried to update the FW so I couldn't have corrupted that.Thank you

author: mrt6644
author_rank: Contributor
timestamp: February 13, 2018, 09:46:58 pm
content: I contacted Siglent support and they sent me an RMA.If my unit had the latest firmware, I could have done a recovery procedure, but mine doesIt.So I’ll send it in.

author: tautech
author_rank: Super Contributor
timestamp: February 13, 2018, 09:49:58 pm
content: Quote from: mrt6644 on February 13, 2018, 09:46:58 pmGreat.Sorry you have to be without it for a bit.
Books/videos/whitepapers and test equipment for EMC/EMI pre-compliance - Page 1
Forum section: electronics / testgear

author: jeremy
author_rank: Super Contributor
timestamp: February 13, 2018, 08:39:44 am
content: Hi all,I was wondering if you’d be kind enough to share with me your EMC/EMI pre-compliance resources (photos or descriptions of your setup, videos, books, anything!). I’m hoping there is a big reference book (like CLRS for algorithms) that everybody looks at that I don’t know aboutI’m potentially in the market for some test gear as well, but I’m not sure exactly how much to spend to get a solid setup (I’m aware it will be many 1000s though). My current equipment is a set of tekbox near field probes and an old anritsu spectrum analyser.The Aaronia kit looks neat for far field measurements:http://www.aaronia.com/products/spectrum-analyzers/EMC-Bundle-2/but I’m not sure if the results I get would be useful enough to warrant the cost. Also, I’ve never used an arronia SA and I don’t know anyone that has. I am certainly not against second hand/refurb.Basically, I’m looking for knowledge and equipment to reduce the chance that a device gets kicked back from the lab as a failure.

author: Kean
author_rank: Unknown
timestamp: February 13, 2018, 09:16:31 am
content: Some good free info published athttps://emcfastpass.com/blog/- but the best stuff is subscription only (I'm guessing).The Aaronia antennas are pretty good, I have the HyperLog 6080 and the BicoLog 30100. I also have the Spectran HF-6080 and don't think much of it - it came buncled with the HyperLog - but the PC software that goes with it isn't too bad, I just prefer to use my other specs. I also have the TekBox DC LISN, probes & amps, some FCC current probes, plus a crappy AC LISN from China. And a couple of other spectrum analysers (Rigol, SignalHound, RF Explorer).To be honest, I hardly use any of this gear. I prefer to send my projects off to a local pre-compliance guy here is Sydney who does this stuff every day. Saves a lot of time and expense over buying your own gear, keeping it in cal, and of course failures at the test lab. If "my guy" says I'm probably over the limit by so many dB in a specific frequency range, then I can pull out this gear (primarily the near field probes or current probes) and try a few things on the bench. But otherwise I can't use it to really make accurate assessments of a pass/fail in-house. I've found the expensive antennas to be the least useful.
BK 2553 boot issue (Siglent 1074CFL) - Page 1
Forum section: electronics / testgear

author: jsantoro
author_rank: Regular Contributor
timestamp: February 13, 2018, 04:47:36 am
content: Hi,I have a BK Precision 2553 70Mhz scope. This is the same scope as the Siglent SDS1074CFL. It has developed a problem when trying to turn it on. I press the power button and the lights blink like normal, but it doesn't boot up. It takes 3-4 times to get it to boot. This just started last week. For now I just leave it on and its fine, wakes up from timeout just fine. Has anyone seen this before in these scopes to point me in the right direction?(Sorry for the cross post to Vintage Computing).Thanks,Jim

author: tautech
author_rank: Super Contributor
timestamp: February 13, 2018, 04:54:50 am
content: Quote from: jsantoro on February 13, 2018, 04:47:36 amHit Math button at boot repeatedly and quickly.Once recovered install any newer firmware from BK.

author: jsantoro
author_rank: Regular Contributor
timestamp: February 13, 2018, 06:14:26 pm
content: Thanks, I'll give that a try. Need to get the firmware from BK, not on their support site.Do you know if Siglent firmware would work? Or am I looking at bricking it?

author: tautech
author_rank: Super Contributor
timestamp: February 13, 2018, 09:08:25 pm
content: Quote from: jsantoro on February 13, 2018, 06:14:26 pmIf you use a Siglent FW be sure to check the version #'s, all but the last few should match.You'll need to install a .cfg (configure) file first before it will accept the Siglent firmware.Have a hunt in the CFL firmware's for a cfg file and last but not least: DO AT YOUR OWN RISK.
Fluke 287 : Unable to solder replacement supercap leads !? - Page 1
Forum section: electronics / testgear

author: sorenkir
author_rank: Regular Contributor
timestamp: February 13, 2018, 02:15:36 pm
content: Hi,As I was planning to replace the leaky supercap of my Fluke 287, I have ordered a Panasonic EECS0HD224H (0.22F 5.5V, horizontal mount version).The size seemed OK, but when bent, the pins are too long, so I have cut the terminal part of each pin.I don't know what kind of metal these leads are made of, but only the very end of each lead (that I have cut) can be soldered.The remaining part is litteraly impossible to solder, the solder does no adhere to the metal, whatever the temperature.Does anyone have an idea ?Michel.

author: Damianos
author_rank: Frequent Contributor
timestamp: February 13, 2018, 06:08:06 pm
content: The capacitors and generally the components are not made to be abused!HereGold Capacitorsmaybe there are some interesting things.
Open Source Instrument Firmware Project - Page 1
Forum section: electronics / testgear

author: rhb
author_rank: Super Contributor
timestamp: February 13, 2018, 03:47:04 pm
content: I am starting work on implementing FOSS test instrument firmware based on the Zynq. The choice of the Zynq is the result of its use in a number of low end scopes, the low cost of competent Zynq dev boards and the good fortune to pick up a Zynq 7010 based Instek GDS-2072E from Amazon for less than the cost of my Zybo Z7-20 dev board.Hopefully at some point analog interfaces to the Zynq will be designed to allow creating a completely open source instrument, but to start the target is COTS scopes based on the Zynq. Alternative FW for existing products.The initial motivation is my annoyance with the existing FW on all the scopes. They all seem to get something seriously wrong. However, this is more ambitious than just reimplementing the existing FW. I am also interested in implementing compressive sensing. Compressive sensing originated in work by David Donoho of Stanford in 2004. A doctoral dissertation on compressive sensing in the context of a DSO was completed a few years ago, but so far as I know, there are no implementations on COTS instruments. The ARM/NEON cores in the Zynq make it especially suitable as a platform for compressive sensing.This thread will continue under the FPGA and Microcontroller section under the same title.
LeCroy Mercury T2 USB Protocol Analyzer - Page 1
Forum section: electronics / testgear

author: bson
author_rank: Unknown
timestamp: February 08, 2018, 03:25:48 am
content: Anyone have experience with the LeCroy Mercury T2?Mainly looking to get a view on signalling issues, tracking what the host does vs what the device sees (e.g. device misinterpreting a suspend as a reset or vice versa), STALL and NAKs, and aid in performance optimization. 2.0 is all I need, and I don't need the 3.0 power negotiation stuff.Is it reliable and usable? It's certainly attractively priced...

author: bson
author_rank: Unknown
timestamp: February 08, 2018, 03:47:06 am
content: Yeah, that's exactly what I want it for. Once enumeration is working I can use other means to debug the higher level device class stuff. Even printfs work for that...And 256MB doesn't seem that small when working with Full Speed.

author: tmbinc
author_rank: Frequent Contributor
timestamp: February 08, 2018, 05:30:44 pm
content: I've worked with the Lecroy Voyager M3i and with the original CATC Advisor (USB2). I liked them - and their proprietary Windows software - a lot, especially compared to alternatives (which aren't bad to begin withif you ignore OpenVizsla). I debugged and hacked a lot of things with them.

author: bson
author_rank: Unknown
timestamp: February 13, 2018, 09:01:22 am
content: Got the Mercury T2 today but spent most of the day doing other things. After a few hours with it learning how to use the UI I must say it's pretty great. In fact, I can't see how NOT to have something like this for USB device work. But it takes a but of time to figure it out; on the first run just using a plain old USB keyboard to get some trace data to play with I was confronted with over 600000 transactions. But it can filter out all the NAKed and STALLed transactions and only show complete transfers. Then group and decode these, with more detailed views. Mousing over a data field brings a decoded popup. It's a sniffer so gets all the various PHY level stuff as well - SOFs, SE0s, RESETs, etc.It has a "spool" mode where it records to disk and it will buffer in PC RAM, so with 32GB RAM it claims to buffer upwards of 10GB of trace data (without disk spooling). Obviously for 2.0 HS since the device itself is only 2.0 HS there needs to be some bandwidth headroom.It has a port for itself to talk to the PC, with separate monitoring ports for host and device (I used a NUC running Linux - CentOS 7 - as the host since it also produces useful dmesg traces).It's scriptable for custom purposes (e.g. application level testing) and can perform 2.0 spec compliance tests although I didn't try these feature yet.The USB Analyzer software has a few minor font and rendering issues on a scaled 4K display.On the whole a pretty nifty little box and the software is very capable!
Replacement Thermocouple for EEV BM235 - Page 1
Forum section: electronics / testgear

author: CarnivalBen
author_rank: Contributor
timestamp: February 15, 2018, 09:22:28 pm
content: I bought an EEV blog Brymen BM235 multimeter, but stupidly damaged the thermocouple.I bought a replacement from eBay but it’s not as good as the original, doesn’t seem to be as acurate, and the banana plugs are not that good.Does anyone know where I can buy a replacement k type thermocouple that is identical to the one you get with the multimeter?

author: Electro Detective
author_rank: Super Contributor
timestamp: February 15, 2018, 09:53:34 pm
content: Perhaps the + and - on the replacement thermocouple are reversed or miss-labelled?I find for average use there isn't a lot of difference between the thermocouple thingies supplied with multimeters and the cheap generics sold at electronics storesFWIW, I had a few on the bench a while back, Fluke, Brymen, Mastech and others compared with a few cheapies from Jaycar Electronics,all immersed in the same container of boiled hot water, and the readings checked as the water cooledI swapped them about at random amongst the meters, and the worst case difference may have been 1 or 2 degrees Celsius,which may have been meter differences too rather than just the thermocouplesAt various points they were all pretty much in agreement, give or take .05so I stopped there and packed the lot away to get the kitchen table back to normal dutiesAnyway it was just a rough go / no go / curiosity test to decide if any are 'better' or more accurate etc and take a note for future referenceand not blow unnecessary dollarsagainYou may have scored a dud thermocouple with a break somewhere from the tip to the banana connectors, it happens
Krohn hite 3343 - Page 1
Forum section: electronics / testgear

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: November 25, 2017, 12:21:10 am
content: Hi guys!Today I have scored an Krohn Hite 3343 dual channel variable filter, I have taked it for only 56 bucks, it is selled as non working (the seller told me that he didn't tested it because he didn't have the knowledge to do it) I consider that a bargain for the price, I will test it when it will arrive.But meanwhile can I have some opinion from you? I haven't finded nothing about it in the blog (probably I don't know how to search properlly), if it have some serious damage I hope that someone can help me!Have a great day

author: duak
author_rank: Super Contributor
timestamp: November 25, 2017, 02:40:33 am
content: I have a K-H 3342R which appears to be similar to the 3343. The only problem I have is that some of the rotary switches are intermittant. These switches are multideck with many contacts and probably just need a good cleaning. The circuit is quite simple and should be easy to set right if there isn't major damage. Hopefully a previous user did not do something like apply mains voltage to the signal ports.I believe xdevs has a downloadable operating and maintenance manual.Best o' Luck,

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: November 25, 2017, 05:18:22 am
content: Thank youI am hoping the same..the rotary seems to be in pretty good conditions, but I have to verify that, is saw some internal photo..and appear to be pretty simple.One thing that I didn't mentioned, the item comes fron a lab, so, I hope for the best

author: scopeman
author_rank: Frequent Contributor
timestamp: February 18, 2018, 02:16:35 am
content: I have the manual for that unit. You may download it at the link below:https://drive.google.com/open?id=1qvcENQyLXE2vhx6oqpJQtOUw6Q0nDXBYI would just do the usual checking of all the power supplies for level and ripple and then clean the switches using Caig DeOxit (use as little as possible).Good luck!SamW3OHM
Which network analyzer? HP 8753 or PicoVNA or ? - Page 1
Forum section: electronics / testgear

author: rfspezi
author_rank: Regular Contributor
timestamp: February 12, 2018, 08:08:02 pm
content: What are the experienced VNA users think when it comes to 6 GHz VNAs?Better buy an old HP 8753 or a PicoVNA for HAM usage?

author: hendorog
author_rank: Super Contributor
timestamp: February 12, 2018, 09:23:48 pm
content: Quote from: rfspezi on February 12, 2018, 08:08:02 pmI think those are both decent choices and you can decide based on price. Haven't used or seen a PicoVNA, but the specs look good, although it has a price to match.There are many 8753's out there and spare parts and knowledge are easy enough to find. The main issue with the 6GHz A/B/C models is that the test sets are hard to find and expensive. Expect to pay over $1000 for a 6GHz test set and between $500 and $1K for the 8753 itself depending on condition. Then you will need a cal kit and adapters for the APC-7 connectors.Personally I don't have a test set, instead I use a dual directional coupler from an 8752 from eBay. I built an RF doubler which I use for the 6GHz range.
Sencore SC61 - Page 1
Forum section: electronics / testgear

author: ohmedarick
author_rank: Newbie
timestamp: May 28, 2017, 06:31:56 pm
content: I hope someone can help me... I have a old Sencore Oscilloscope its around 20 years old and has not been turned on since... I'm afraid to turn it on because of a faulty capacitor due to age . What is your recommendation. Should I open the unit first and check some the components before turning on the scope. Please help me. Thanks?

author: BOB-LEWIS
author_rank: Newbie
timestamp: February 12, 2018, 06:25:08 pm
content: Hi, Ohmedarik,I have one of these, also. It hasn't been powered up since it was given to me. What I'm planning is to plug it in to a Variac Transformer and bring it up[ to 120 VAC over a period of a few hours. It will probably be a while before I tackle that job, since we're recovering from a Basement "rehab". I see this has been posted for several months.I hope you have had success with the instrument.
Leader LBO-3B Oscilloscope circuit diagram? - Page 1
Forum section: electronics / testgear

author: Fifbua
author_rank: Newbie
timestamp: February 10, 2018, 01:06:55 pm
content: Hi everybody,have been searching this forum and the web for quite a while now for a circuit diagram of aLeader (Japan) LBO-3B oscilloscope- without success. The unit I have has strange jacks/jumpers and a switch in the rear of the instrument behind a cover. I wanted to grasp what these are for and was hoping to be enlightened by a circuit diagram, if one still exists somewhere.I was planning to restore my unit to use it for low frequency xy-tracing.Any help with this is much appreciated.Many thanks,Alex

author: Fifbua
author_rank: Newbie
timestamp: February 12, 2018, 12:45:18 pm
content: Gentlemen,by the way: my LBO-3B unit is made in 1938 according to the quailty-check card inside the instrument. I have the impression that I was the very first person to open the unit after 80 years.
Fluke 8840A or 8842A?  how to tell when display window is missing? - Page 1
Forum section: electronics / testgear

author: spok
author_rank: Newbie
timestamp: February 11, 2018, 10:25:15 pm
content: I apologize if this post is in the wrong place, or has been asked before. I did search the blog without any luck.I acquired a Fluke 8840A (according to the eBay seller) which works perfectly but is missing its display window.How can I find out if it is an 8840A or actually an 8842A? From what I can see they look identical except for the logo on the display window?I do hope someone can help me as I'm trying to acquire a display window for this amazing meter.

author: MadTux
author_rank: Frequent Contributor
timestamp: February 11, 2018, 10:57:01 pm
content: Quote from: spok on February 11, 2018, 10:25:15 pmNo, they don't. It's actually not even hard to spot the difference:https://www.mikrocontroller.net/attachment/246613/f-5.JPGhttps://accusrc.com/uploads/images/img3519.jpg

author: ArthurDent
author_rank: Super Contributor
timestamp: February 12, 2018, 12:25:51 am
content: Compare the two photos MadTux linked to and check the location of the AUTO button on the front panel.I got a 8840 that was missing the window and the seller said the A.C. function gave an error so I paid $16 for it. The A.C. was an uninstalled option. I cut a window out of thin colored Lexan and held it in place with double sided tape.
GW-Instek GPE-2323 / RS Pro RPE-2323 power supply review - Page 1
Forum section: electronics / testgear

author: Deckert
author_rank: Regular Contributor
timestamp: July 12, 2017, 11:01:14 pm
content: Hi guys,I've seen a few questions about it on the forum, so I did a quick-ish review of the GPE-2323 power supply at the link down below. I have the RS Pro unit, since shipping by other means to my country is a nightmare in terms of consistency. I'll hopefully complete part 2 (a teardown / look inside) over the coming weekend, so let me know if there are other questions or things you want to see inside.--deckert

author: Daruosha
author_rank: Regular Contributor
timestamp: July 14, 2017, 04:10:17 pm
content: Thanks for your nice review. Is there a teardown video as well? I'm struggling to buy the 4 channel version of this power supply, but I am not sure about the build quality (transformer, caps, ...).I'd appreciate if you could bother with taking it apart and show us the inside.

author: Deckert
author_rank: Regular Contributor
timestamp: July 14, 2017, 11:17:43 pm
content: Yes, teardown video coming soon! Need to see what's inside it myself :-)--deckert

author: Deckert
author_rank: Regular Contributor
timestamp: July 19, 2017, 07:31:35 am
content: As promised, a teardown of this power supply:--deckert

author: Coceth
author_rank: Contributor
timestamp: October 03, 2017, 10:32:24 am
content: Very nice review + teardown. The GPE-2323 has a lot going for it (inexpensive, output on/off switch, 1mA resolution). Do you wish you had a third and forth output, or are the two outputs adequate?

author: auclairD
author_rank: Newbie
timestamp: November 05, 2017, 03:04:12 pm
content: Thank you Deckert! This thourough review convinced me to make the move on this unit. I was looking for a solid supply capable of 48v - 54v and this one looks like a quality build, more than just good appearance.

author: Deckert
author_rank: Regular Contributor
timestamp: February 11, 2018, 09:13:25 pm
content: Hi - one last update on this supply.I made a very short (2 minute) video on how to reduce the fan noise by adding a series resistor to the fan. It reduced the fan noise significantly without incurring too much penalty in terms of temperature rise (measured a max of 60 degrees C on the main heat-sink at full load on both channels).--deckert
Unusual LCD failure TDS3054 - Page 1
Forum section: electronics / testgear

author: Jwalling
author_rank: Unknown
timestamp: February 11, 2018, 03:27:34 pm
content: I don't think I've ever seen an LCD that fails with a vertical or horizontal line that didn't extend completely from side to side (or top to bottom)Something new everyday...

author: nctnico
author_rank: Super Contributor
timestamp: February 11, 2018, 03:44:25 pm
content: This could be a problem in the internal circuitry of the oscilloscope and not the display because it seems to occur in the signal trace overlay area. I'd try a different LCD first!

author: Jwalling
author_rank: Unknown
timestamp: February 11, 2018, 03:55:39 pm
content: Quote from: nctnico on February 11, 2018, 03:44:25 pmOh, I did! The replacement is fine.

author: nctnico
author_rank: Super Contributor
timestamp: February 11, 2018, 04:00:52 pm
content: Quote from: Jwalling on February 11, 2018, 03:55:39 pmWell then it certainly is an odd failure! Perhaps one of the traces on the glass itself got interrupted. I have seen localised defects in LCD screen though.

author: Jwalling
author_rank: Unknown
timestamp: February 11, 2018, 04:16:09 pm
content: Quote from: nctnico on February 11, 2018, 04:00:52 pmThat would make perfect sense if the driver chip was on the bottom! Good call. I'd dissect it if I weren't going to use it as a test display...I wonder how it could happen though; there's a protective anti-glare glass that covers the LCD.

author: voltsandjolts
author_rank: Unknown
timestamp: February 11, 2018, 04:34:32 pm
content: Where did you get the replacement LCD, from Tek?

author: Jwalling
author_rank: Unknown
timestamp: February 11, 2018, 04:37:17 pm
content: Quote from: voltsandjolts on February 11, 2018, 04:34:32 pmIf I had, my wallet would probably be $500 lighter, assuming that they're not obsolete.I bought a couple of spares off eBay a year or two ago.

author: voltsandjolts
author_rank: Unknown
timestamp: February 11, 2018, 04:39:41 pm
content: Hah, nice, wise move!
HP Power Supplies - 6002 vs 6024 vs 6038 - Page 1
Forum section: electronics / testgear

author: davefr
author_rank: Contributor
timestamp: February 13, 2018, 12:02:19 am
content: Hi,I'm looking for a linear DC power supply that can provide voltages up to around 50 VDC. It seems like HP/Agilent has three older models that are affordable on Ebay. (6002A, 6024A and 6038A).I don't need GPIB or any fancy features and prefer a reliable model given that these things are pretty old. (don't need digital readouts unless the 6038A is a significantly better model)Out of these three, is there a "sweet spot"?TIA

author: wn1fju
author_rank: Frequent Contributor
timestamp: February 13, 2018, 01:07:24 am
content: You did not say what kind of current you need. Or whether you want single or dual output. With all the "older" models, you have to beprepared to do your own maintenance (i.e., fix it). Not sure why you are restricting yourself to HP models. Check out some of the otherofferings, for instance, Power Designs models.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 13, 2018, 04:07:39 am
content: The old HP and Harrison power supplies are built like a tank and are almost as heavy. Shipping could easily cost more than the PS so I look for ones for sale locally (yes, on E-bay) and that I can pick up in person and save on the shipping. But you need to contact the seller first and see if they allow local pickup or if they charge a fee.As far as which PS is "best" it just depends on your needs as far as voltage and current range, features, % of regulation, allowable ripple, weight and size, etc etc. But the thing that I do like about the older HP PSs is that they're designed and built to last forever and there are service manuals available and most of older ones uses standard, readily available, discrete parts.I have a closet half full of HP power supplies. My newest one is a 20 year old HP 66312A that I just picked up and I know that several of the others date back the early 1960s. I would say that at LEAST 80% of the HP supplies that I have were working fine when I got them and probably half of them literally came out of someone's scrap pile.PS on most of the old HP PSs, the analog meters are dammed accurate! I can state for a fact that they're more accurate than the digital displays on the newish Chinese PSs that I've tested.

author: edpalmer42
author_rank: Super Contributor
timestamp: February 13, 2018, 04:16:49 am
content: I have a 6002A supply that I picked up recently. It was dead so I got it cheap. When I pulled the bottom off it, I wondered "Should this cable be hanging like that or should it be plugged into the matching connector that's right there?".One thing I've found is that the fan is LOUD. It doesn't seem to be bearings, it just moves a lot of air. It's also not so easy to quiet it down because it's powered by 110AC. There's no convenient place to pick off 12V to power a newer fan. I think I'm going to use a capacitor to drop the voltage without dissipating power like a resistor. Looks like something in the 2 or 3 uf range should be about right.Ed
Vintage Todd Products Variable Power Supply Teardown - Page 1
Forum section: electronics / testgear

author: Technobabble_
author_rank: Regular Contributor
timestamp: February 10, 2018, 03:08:56 am
content: Happy FridayFound this little guy at the local surplus center. Interestingly, it has what appears to be a 3M inventory number (3M is a local company). Multimeter test shows that output voltage is almost spot on.

author: Technobabble_
author_rank: Regular Contributor
timestamp: February 10, 2018, 03:09:48 am
content: Additonal shots:
HP 3314A Front feet - Page 1
Forum section: electronics / testgear

author: kr5j
author_rank: Contributor
timestamp: February 10, 2018, 04:50:54 pm
content: Just acquired a working HP3314A Function Generator and would like to find front feet for it. I have to prop it up on the bench to see the front panel. Some feet that pop open to raise the front panel so I can see it would be helpful.

author: Kean
author_rank: Unknown
timestamp: February 10, 2018, 06:12:23 pm
content: Not sure if the 3314A uses the same style feet as later HP/Agilent models, but I bought a bunch of these for my 3478A's and 5384/5385.https://www.ebay.com/itm/Set-of-2-Instrument-Feet-w-wire-bails-HP-AT-Light-Grey/380632426855He sells them in pairs (that listing), as well as lots of 4, 8, and 16 - for front & back feet. Quite useful if you expect to buy a bunch of old HP/Agilent gear.
DSOX2012A hackable ? - Page 1
Forum section: electronics / testgear

author: maxpayne
author_rank: Regular Contributor
timestamp: February 10, 2018, 07:19:35 am
content: I am planning to buy the scope Keysight DSOX2012A 100MHzhttps://www.keysight.com/en/pdx-x201831-pn-DSOX2012A/oscilloscope-100-mhz-2-analog-channels?cc=US&lc=engI know Dave has video of hacking DSOX1000 series for higher bandwidth. I also searched in the forum if anyone has done the same for 2000 series. But I was unable to find any.I mainly need to hack it for the following option -Memory upgradehttps://www.keysight.com/en/pdx-x201978-pn-DSOX2000-010/infiniivision-2000-x-series-oscilloscopes-memory-upgrade?nid=-32542.1150548&cc=MY&lc=engSegmented memoryhttps://www.keysight.com/en/pd-1952332-pn-DSOX2000-SGM/segmented-memory-acquisition-for-infiniivision-2000-x-series-oscilloscopes?nid=-32976.970773&cc=MY&lc=engBandwidth upgradehttps://www.keysight.com/en/pdx-2698187-pn-DSOX2BW22/bandwidth-upgrade-from-100-mhz-to-200-mhz-on-2-channel-models?nid=-32542.1179859&cc=MY&lc=engIs there any hacking guide to upgrade the following feature ?

author: gamalot
author_rank: Super Contributor
timestamp: February 10, 2018, 07:38:43 am
content: https://www.eevblog.com/forum/testgear/dsox2000-and-3000-series-licence-have-anyone-tried-to-hack-that-scope/

author: Hydrawerk
author_rank: Super Contributor
timestamp: February 10, 2018, 04:24:26 pm
content: Agilent / Keysight DSOX2000 series was introduced in 2011.It is seven years old now.Wait till March 2018 or so. They might be releasing a new scope...

author: Pinkus
author_rank: Frequent Contributor
timestamp: February 10, 2018, 05:30:04 pm
content: Quote from: Hydrawerk on February 10, 2018, 04:24:26 pmYeah - but hacking will probably not possible ......Anyway, as I already wrote in the other thread:I would advice not to purchase one: The DSOX2000 series does not allow serial protocol analysis on the digital channels (only analogue channels) and with only two analogue channels you will be stucked quickly (e.g. with a simple SPI protocol).Better get a 2-channel 3000-series scope (they allow protocol analysis on digital channels) or go for the 4-channel version of a DSOX2000 series scope.
Elmeasco Model 710B Microohm Meter - Retro Teardown - Page 1
Forum section: electronics / testgear

author: sean0118
author_rank: Frequent Contributor
timestamp: February 10, 2018, 02:32:30 am
content: Hey everyone, I found an Elmeasco Model 710B Microohm Meter recently, there's almost no information about it online so I thought I would share some teardown pics on the forum.Elmeasco was an Australian company and it looks like the date code on one of the ICs places it to ~1972,Enjoy!

author: Vgkid
author_rank: Super Contributor
timestamp: February 10, 2018, 06:42:45 am
content: Thanks for tearing it down , pretty neat piece of gear.

author: beanflying
author_rank: Super Contributor
timestamp: February 10, 2018, 07:00:55 am
content: Love it Ceramic IC in a wooden case not quite sure if we are old school or 'new' school