hybridfree/eevblog-posts huggingface dataset:
Keithley AC amps accuracy specs and noise floor - Page 1
Forum section: electronics / testgear

author: jpb
author_rank: Super Contributor
timestamp: June 13, 2014, 10:07:08 pm
content: There is a long thread on the rms converter noise on a Keithley 2000 or 2015 :https://www.eevblog.com/forum/testgear/keithley-2000-trms-converter-noise/Whilst testing my newly purchase K2015 on AC current I found that there was a noise floor of over a mA on the lowest range even though the specs for error are 0.04% which is 0.4mA.But the manual states that the VAC offset is typically 100 counts or 1mV.The burden voltage on the DC 1A range is 0.3V or less which implies a sense resistor of 0.3 ohms BUT for AC I think the sense resistor is 1 ohm so the AC current noise floor is 1mA >> 0.4mA.As evidence the first picture is ACV with short circuits for my two metersthe rms VAC is 1.499 mV and 1.000 mVthe second picture shows the AAC values with open circuits the rms noise is1.497 mA and 1.070 mA.Perhaps others with these meters can test theirs.EDIT - CorrectionGrumpydoc points out that the shunt resistor is 0.1 ohmsSo it is a bit mysterious - there seems to be a 1 mA to 1 mV correlation between the noise or offsets which should correspond to 1 ohm but it is actually 0.1 ohms.

author: jpb
author_rank: Super Contributor
timestamp: June 13, 2014, 10:43:15 pm
content: I've now directly measured the resistance at 0.2893 ohms which corresponds to the official burden voltage specs of < 0.3V rms on the 1A range.But the actual shunt resistor is 0.1 ohms according to the spec sheet.I guess this means there is 0.189 or approximately 0.2 ohms of resistance in series.It still leaves the mystery as to why the AAC noise is so high.

author: G0HZU
author_rank: Super Contributor
timestamp: June 13, 2014, 11:18:43 pm
content: I don't think you are meant to trust the 2015 DMM below 5% of FSD on ACV and ACI. If you go down as far as 1% of FSD I'd expect the rms detector to lose bandwidth and accuracy.Mine appears to only have a 1A and 3A range for ACI so it's obviously going to be poor at measuring low level ACI if you obey the 5% limit for the rms detector in the specs.

author: jpb
author_rank: Super Contributor
timestamp: June 13, 2014, 11:34:39 pm
content: Quote from: G0HZU on June 13, 2014, 11:18:43 pmYes, I think you're right - the calibration point is at 1A (as that is full scale on the lowest range).Interestingly my calibration certificate states my meter measured 1A ac with an error of just 6 ppm or 6 microAmps even though the offset at zero input is 1.5 mA.I guess this comes down to 1A being 100 mV across the 0.1 ohm shunt and sqrt(100mV^2 + 1.5mV^2) is 100.011 so the effect is diminished though it is still going to correspond to 0.011mV/0.1ohms = 110 microAmps which is much more than 6 microAmps.
eBay Fluke 77/23 Square D multimeter score - Page 1
Forum section: electronics / testgear

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 13, 2014, 03:00:08 pm
content: Never seen one before. The Square D WMM-23 is obviously a re-badged Fluke 23 (same as a 77 inside).But in my opinion looks way cooler than either of the Fluke models.$25.99 freight included.

author: TVman
author_rank: Frequent Contributor
timestamp: June 13, 2014, 03:07:37 pm
content: Wow!That was a really good deal.I NEED to scrap eBay more.Hunor.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 13, 2014, 09:10:49 pm
content: About June 2013, I alerted Excavatoree about one on ebay, but that auction's unit is not in great shape.http://cgi.ebay.com/111090066239

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 13, 2014, 09:33:14 pm
content: Quote from: retiredcaps on June 13, 2014, 09:10:49 pmYeah - this one is in beautiful condition. A couple digit segments were fading so I serviced it for that. It fought me and at first I thought it was a mistake to try, but after several attempts, the display contrast is beautiful; noticeably better than my otherwise good model 77. A week or more later the digits are still perfect so I'm going to assume it will hold up.Also, there was some dirt and - or - grit around and under the function knob area. Felt a bit crunchy when turning the knob. Dis-assembly, cleaning and a bit of plastic gear grease made it like new. Also could not help myself, I adjusted the meter just a bit to more closely agree with my other Flukes - just a milli-volt or two, really.Could not help myself on that auction- I had a pretty high maximum bid, but NO ONE else even bid on it. Score!

author: retiredcaps
author_rank: Super Contributor
timestamp: June 13, 2014, 09:44:48 pm
content: Quote from: mzacharias on June 13, 2014, 09:33:14 pmThe seller correctly listed it with the right auction title and everything, but if he would have known the relationship to Fluke, he would have attracted more bids.Anyway, good score and I'm sure Excavatoree is wondering why I didn't alert him??PS. I love your youtube videos. Any chance you are going to make more soon?

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 13, 2014, 11:00:11 pm
content: It's kinda hard to justify taking time away from business when business is slow - feels like I'm stealing from my own company.Been wanting to do one on modern receiver protection circuits, though. Trouble is, too many unqualified people would try to fix their own.Still might do it though, maybe with a disclaimer...

author: Excavatoree
author_rank: Frequent Contributor
timestamp: June 13, 2014, 11:22:28 pm
content: Quote from: retiredcaps on June 13, 2014, 09:44:48 pmI've got a new, in box example, along with the poor condition one you told me about. That's enough. The OP did get a great deal.Square D even made their own holster with no "Fluke" molded into it anywhere, and they reprinted the manual with no mention of Fluke at all. The only "Fluke" on these is on the circuit board.
ESI RS925A Decade Resistance Standard - Mini Teardown - Page 1
Forum section: electronics / testgear

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 15, 2014, 01:45:09 am
content: Hi,On my trip to Dayton this year I picked up an ESI RS925A Resistance Standard. This is a very precise metrology grade decade resistance. It is an alternative to the General Radio 1433 series that Dave did a teardown in video 461.The ESI decade box dates back to the mid 1960s. The current version RS925D is still available from IET Labs for a mere $16,000. The D version has some trimmers to facilitate calibration.SchematicA little different. The lowest decade is a potentiometer.SpecificationsReally outstanding specifications.ConstructionOutside views:The ESI resistance standard using conventional switches, but four switch decks are wired in parallel.The resistors are wound on Mica formers.Several Decades:This is the variable 10m Ohm decade:So how good is it?All the measurements were made with a Datron 1281 in the 4W ohms mode:10K Ohm (10 ppm error)100K (42 ppm error)1M (33 ppm error)20K (20 ppm error)Regards,Jay_Diddy_B

author: Vgkid
author_rank: Super Contributor
timestamp: June 15, 2014, 03:28:04 am
content: Wow impressive score. That unit is really stable considering that its accuracy is 50ppm max for longer than one year. It was also used in the ESI 242 resistance bridge.

author: quarks
author_rank: Frequent Contributor
timestamp: June 15, 2014, 05:12:48 am
content: very nicewhen I looked into precise resistance measurement solutionshttps://www.eevblog.com/forum/chat/help-wanted-low-and-high-ohm-measuremet/msg169139/#msg169139I found the esi rs925 series as part of the esi 242 resistance measuring system is one of the very best ever made piece of gear of this kindBTW 10k is only 1ppm off in your picture
Buying RIGOL DSO - from Hongkong / Support ? - Page 1
Forum section: electronics / testgear

author: TinkeringSteve
author_rank: Frequent Contributor
timestamp: June 12, 2014, 08:32:59 pm
content: Hey there.I see there on ebay, a seller with good reputation called "lotusdechine2006" who's known to sell all those china scopes from Hongkong.I actually bought my Hantek there years ago.But since the thing didn't have any defects so far, I never had to deal with support, either from that seller, or with a chinese oscilloscope maker of moderate to good reputation, product wise.Now I've been annoyed multiple times by only having 2 channels and low memory depth, so I've decided to upgrade, or more precisely, to get one of the lower (but not lowest) new style Rigol scopes, with ultravision blah and 4 channels.The mentioned ebay seller sells those for a good price. Buying from usual electronic sellers in Germany, it would cost ~ 27% or almost 150 EUR more than with the honkong guy.(Note, as stated by the guy, there will be no extra cost like customs, since they are sending it from Honkong to London, then further into europe - apparently there are special rules. I didn't pay customs back then for the other scope either.)So now I'm hesitating, this is some more dough than for my hantek back then.Does anyone here have experience with support from the seller or/and Rigol ?Does Rigol have a support base in Europe, or would I have to send defective gear to China? Which would be quite expensive I imagine.- regards

author: TomThomas
author_rank: Contributor
timestamp: June 12, 2014, 09:45:10 pm
content: Quote from: TinkeringSteve on June 12, 2014, 08:32:59 pmHi,Rigol has a branch Office in Europe / Germany, where they can do the support. But this is only valid for Rigol Instrumentation which was sold within Europe.So in the worst case... if you have an issue, it could be possible that they refuse and you have to send it to Hongkong.I personally would go and buy at an official Rigol reseller from Europe. I did it that way..BRTom

author: rob77
author_rank: Super Contributor
timestamp: June 12, 2014, 09:53:49 pm
content: and exactly those concerns were the reason why i did buy my Hantek here in a brick-and-mortar shop (100-150Euro more expensive than china/ebay/whatever shops).i got 2 years of warranty and i don't have to worry about anything.. if it breaks down, i'll just return it to the shop - and they WILL HAVE TO take care (and arrange the repair/replacement within 30 days) .. so it's worth of the extra cost - i'm happy
Hantek MSO5102D (Voltcraft MSO-5102B) crashes - Page 1
Forum section: electronics / testgear

author: mr.burns
author_rank: Newbie
timestamp: April 20, 2014, 11:03:33 am
content: Dear all,In Germany I bought a Voltcraft MSO-5102B (with 16 Ch. logic analyzer) from a German supplier Conrad Electronics.This is the same DSO as your MSO-5102D. I am very happy with this devicde but it contains a bug:I press the 'Display' button and then 'F6' to get into the page 2/2 of the display menu.There I can change the style of the grid from dot to line. If I press 'F1' to change ths style from dot (default) to line the divece freezes completely. The display turns black. After aroound 20 seconds the decvice boots up again with the Voltcraft logo.This bug is repeatable, so it's really a bug. The problem occurs also if I use the 'Virtual panel' or 'setup-->Device-->Grid type' out of the Windows software which comes with the device. Is this a known bug? If you own a MSO-5102D can you check if the problem occurs also on your device please?I contacted the German company Conrad Electronics but they neither can tell me what is the latest firmware for this device nor they provide any firmware. So I must live with this bug or give back the device which I don't want. I like the device!Since my device is same as the Hantek MSO-5102D my question if I can download the firmware from Hantek's website and install it to my device?If I go to the system menu and bring upd the firmware information it says:SW-Version: 3.2.35(130506.0)HW-Version: 1010x55558340Thanks for any help!

author: Mark_O
author_rank: Frequent Contributor
timestamp: April 21, 2014, 05:59:03 am
content: Quote from: mr.burns on April 20, 2014, 11:03:33 amThat doesn't bode well for the future.

author: mr.burns
author_rank: Newbie
timestamp: April 21, 2014, 11:19:49 am
content: Hi,Quoteseems soTherefore I am looking for an alternative, can someone please tell me if I can use the firmware from Hantek MSO-5102D?Still need help...

author: Carrington
author_rank: Super Contributor
timestamp: April 21, 2014, 11:54:13 am
content: Sorry, but I can't say anything good about Conrad. They tried to cheat me, even deleted my user account.@mr.burns: Contact with "tinhead", maybe he can help you.

author: Fig
author_rank: Newbie
timestamp: June 12, 2014, 01:31:20 am
content: Hi,I also recently purchased the MSO5102D mixed signal oscilloscope. Connected to my PC the virtual panel crashes. It disconnects and asks if I want to reconnect. I hear the scope click a few times and the disconnects or tries to reconnect.I emailed Hantek with the same question you had about the firmware.sw 3.2.35(140312.0)is the latest.I also emailed them today about the virtual panel crash. I ask Hantek if I was running the latest version of MSOscope. Everything else seems to work correctly. I haven't tried the logic analyzer portion yet.
TDS5/6/7xx PSU behavior in standby? - Page 1
Forum section: electronics / testgear

author: siggi
author_rank: Regular Contributor
timestamp: June 11, 2014, 03:36:00 pm
content: Hi y'all,I'm trying to repair a TDS684A, which came to me with a broken standby power supply. I've fixed that, but when I power the scope, it hiccups, e.g. the front panel lights and fan turn on and off. I've tried disconnecting the CRT and acq boards, but this doesn't change anything, so I'm looking at the PSU again in more detail.One thing I noticed is that my PFC regulates fairly high at 417V when I feed it 60V DC for input. When I feed it mains, it runs from 424V to 437V where it bumps into the over voltage lockout, at a frequency of about 1Hz. This is one of the older PSUs that has a PFC riser board full of discretes, btw. I've checked the 2.5V reference, which is spot on, and everything in the PFC otherwise looks as described in the TDS520 SM.I wonder if this is behaving as expected, as I can then strike it off my list of things to further look into.Anyone?Also, the 684A SM has a table with expected output voltages from an unloaded supply. Mine's reading low on the 24V rail in particular (it's ramping from 8-9V with a period of ~180ms).Since these PSUs were outsourced and frequently revised, I wonder how much stock I can put in these troubleshooting guidelines in the SM?Siggi

author: nctnico
author_rank: Super Contributor
timestamp: June 11, 2014, 10:15:16 pm
content: In standby these PSUs are in hick-up mode. If you listen closely to the scope in standby you'll hear it ticking in a 1 HZ ritme.

author: siggi
author_rank: Regular Contributor
timestamp: June 12, 2014, 01:24:42 pm
content: Quote from: nctnico on June 11, 2014, 10:15:16 pmThanks - this is indeed what I observed. I've bolted the PSU back in the scope, essentially just with a fixed standby supply and a new bulk cap.It was now able to power the processor and CRT without trouble, but when I added the acquisition board it went into hiccups. After a while it "cleared up", guess the PSU burned through shorted bypass caps.In any case, I have suspicious-looking residue around some of the SMT caps on the acquisition board, so likely I suffer from capacitor plague.At least that's something I believe I can fix.
Service manual Wandel & Goltermann PJM-4 Jitter Meter - Page 1
Forum section: electronics / testgear

author: davorin
author_rank: Unknown
timestamp: June 11, 2014, 10:48:43 pm
content: I saw some reference when searching with Google to the documents named:Service Manual PJM-4 jitter meters BN 2019But nowhere a version which could be downloaded...I acquired this model which just displays upon power up several hardware errors, beeps like mad and doesn't stop switching relays (o;
Cheap spectrum analyser - Page 1
Forum section: electronics / testgear

author: LukeW
author_rank: Frequent Contributor
timestamp: June 10, 2014, 06:46:23 am
content: Anyone have any recommendations for a spectrum analyser that is not a rubbish toy but is also low-cost and good value?In terms of specific budget, let's say a couple of k, or $5k at the most.I've been looking at the Rigol DSA1030 at the moment... anyone with experience with that unit, or recommendations for anything else that is similarly priced?It would be really desirable to have something that runs up to 3 GHz, for RF work with 2.4 GHz devices.

author: VK5RC
author_rank: Unknown
timestamp: June 10, 2014, 10:47:02 am
content: What frequency do you have to get to, good second hand ok? A trusted HP SA?

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 10:55:06 am
content: Which country are you in? Good second hand equipment is a lot more readily available in some countries than others.

author: Psi
author_rank: Super Contributor
timestamp: June 10, 2014, 11:54:19 am
content: Does it need to be a all-in-one unit with a LCD?Some of the PC based analyzers are quite good.Also do you need a tracking gen

author: nctnico
author_rank: Super Contributor
timestamp: June 11, 2014, 11:14:37 am
content: Quote from: LukeW on June 10, 2014, 06:46:23 amDoes it need to be new? Advantest has several models with an LCD screen which certainly can be bought from Ebay with that budget.

author: dannyf
author_rank: Super Contributor
timestamp: June 11, 2014, 11:16:31 am
content: QuoteDepending on your requirement, those SDR sticks can be used as a spectrum analyzer.Usually around $10 - 20 each.

author: w2aew
author_rank: Super Contributor
timestamp: June 11, 2014, 03:47:51 pm
content: Quote from: LukeW on June 10, 2014, 06:46:23 amWith the current promotion that Tek is running on the MDO3000 series of mixed domain oscilloscopes, you get the 3GHz spectrum analyzer upgrade for free. In your case, you can think of this as a basic 3GHz spectrum analyzer with a free scope attached.
Agilent U8002A PS schematic - Page 1
Forum section: electronics / testgear

author: thooker
author_rank: Newbie
timestamp: November 19, 2013, 04:36:27 am
content: I purchased a broken Agilent U8002A power supply on EBAY a few weeks ago, and would like to repair it. Agilent does not have a schematic on their web site. Does anyone have a schematic of the U8001A / U8002A supplies?Thanks,Tracy

author: thooker
author_rank: Newbie
timestamp: November 20, 2013, 06:37:19 am
content: I contacted an Agilent rep and he is also looking. They dont offer a real service manual. The Agilent rep contacted the factory and they said that by the time you sent it in for repair, it would be better just to buy another.So, I am still looking for a schematic!

author: max-bit
author_rank: Frequent Contributor
timestamp: November 20, 2013, 07:04:22 am
content: I doubt that someone shared schemaif not on the website agilent it will be big trouble

author: Nermash
author_rank: Frequent Contributor
timestamp: November 20, 2013, 07:38:50 am
content: AFAIK Agilent does not release publicly any schematics for products designed after the HP era.I doubt that even their service centers have it, most repairs are done on the module level.Post initial symptoms here, some of your findings, measurements and thoughts about the issue and maybe someone will help you.

author: thooker
author_rank: Newbie
timestamp: December 04, 2013, 10:02:35 pm
content: The patient is the Agilent U8002 power supply. Attempting to adjust the voltage or current above 0, and turning the output ON causes the V to flash. Looking at the output of the power supply shows no voltage change: the output is always <50mV DC.I took it apart, and the obviously dead parts are Q5, a IRFP150N, and D5, part unidentified. They are all in the vicinity between the large heatsink and the large capacitors: obviously the voltage regulation circuit. It looks like the IRFP150 got hot enough to spew, and spilled stuff out in the area. I cleaned it up, and it looks pretty good now.R10 and R58 (both next to D5) looks a little worse for wear, and I will replace them: R10 looks like a 47K, but I cant read what R58 is. D5 looks to be a zener, but I have no identifying information for it.I have some IRFP4468 units, which looks like the same family but heavier duty parts, so that should work for Q5. I need help identifying D5 and R58.After I replace these parts, I will post more information.Thanks,TH

author: reagle
author_rank: Unknown
timestamp: June 10, 2014, 01:05:33 am
content: How is your repair going? I just grabbed a non-booting one off ebay myself

author: sorin
author_rank: Frequent Contributor
timestamp: June 11, 2014, 10:40:07 am
content: SCHEMATIChttp://www.amobbs.com/forum.php?mod=viewthread&action=printable&tid=4722574http://www.amobbs.com/thread-4755363-1-1.html
Advantest R6161 - 6 1/2 digit voltage & current source - Page 1
Forum section: electronics / testgear

author: theatrus
author_rank: Frequent Contributor
timestamp: June 10, 2014, 05:59:36 am
content: Its true, once you start going volt-nutting, its hard to stop. Introducing my latest eBay find (not the 3458a):The Advantest/ADCMT R6161 6 1/2 digit voltage and current source, at an order of magnitude less money than the current reseller prices.The big brother to Dave's R6142:https://www.eevblog.com/forum/blog/eevblog-576-advantest-r6142-current-voltage-generator/This unit has a 10nV step size at the lowest range, and can output up to +/- 1200V, with a 10nA-120mA current range.Full specs:http://ds.theatr.us/test-equipment/Advantest/Advantest_R6161.PDFManual (this took me awhile to find):http://ds.theatr.us/test-equipment/Advantest/R6161_FOE-8311242C02.pdfTranslatinghttp://www.adcmt.com/techinfo/product/end_of_sale/R6161/i_6161.htmlgives this tidbit: "Josephson voltage standard system ensures high accuracy"I'll do a teardown soon to see what kinds of unobtanium make up this unit.

author: EEVblog
author_rank: Unknown
timestamp: June 10, 2014, 12:07:50 pm
content: Nice!One just went for $680 on ebay.

author: Vgkid
author_rank: Super Contributor
timestamp: June 11, 2014, 12:40:15 am
content: Wow, that is impressively accurate when compared to specs.

author: quarks
author_rank: Frequent Contributor
timestamp: June 11, 2014, 03:52:14 am
content: very nice, looking forward to see your teardownbyequarks
Luminance Meters - Page 1
Forum section: electronics / testgear

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 09, 2014, 08:02:47 pm
content: Anyone have any experience with luminance meters for looking at brightness of LCD panels? We are looking for something to verify backlight brightness vs current to evaluate some backlight options on mid side LCD displays.I'm not sure what level I need to go to for decently accurate readings. Most of what I see are for indirect brightness, as you would measure to set a camera exposure, rather than radiated brightness. Not sure if that matter though.

author: DJ
author_rank: Unknown
timestamp: June 10, 2014, 12:54:00 am
content: Maybe this unit?http://spyder.datacolor.com/portfolio-view/spyder4elite/If not, might be looking for one of the Minolta LS-1xx units (pricey though)

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 11, 2014, 03:00:55 am
content: Those are more for color calibration. We are looking for just brightness measurement. The Minolta looks like the high end of those we found.We decided to get a ~$150 Extech meter, that has the opaque white typical light meter. We will get relative numbers, rather than trusted absolute, but that is OK for now. Not sure what equipment is required to verify something like 300 nits for a smart phone screen, but it is probably fairly pricey.
Calibration : Fluke 52 II Series thermometer - Page 1
Forum section: electronics / testgear

author: TiN
author_rank: Super Contributor
timestamp: June 10, 2014, 02:27:25 pm
content: I'm back home, and what we have here for today?Guesses?

author: TiN
author_rank: Super Contributor
timestamp: June 10, 2014, 02:28:05 pm
content: Fluke service manual with calibration procedure.Fluke recommends 5700A calibrator, but we will use poor-man DC standard, EDC MV106.Initial inspection, "before calibration" state.On right side - ADC calibration fixture (two-copper terminal jack made from two thermocouple T jacks).Cal sticker is tampered.-82°C with tested K-type thermocouple hanging in +25C room temp ain't right.Closeup for connector used for voltage source (EDC MV106 DC standard calibrated to Keithley 2001 with Tek cal 5.FEB.2014) connection to Fluke 52-2 inputs.I used copper wire from UTP LAN cable.0.0000v set - meter shows 20-30C...Calibration A-D convertor by providing 80.0000mV and -8.00000mV to inputs.-8.00000mV read as -7996.9 uV, which is in range for calibration requirements of –7995.0 to –8005.0.Calibration reference point:REF point offset is 3.8C.After corrected offset:"After calibration" Performance test values (K-Type Thermocouple) with icebath.Channel 1 on left, channel 2 on right:1. 0.0000 mVDC / 0.0 °C2. 0.9193 mVDC / 23.0 °C3. -5.7297 mVDC / -190.0 °C4. 40.8853 mVDC / 990.0 °C5. 48.8382 mVDC / 1200 °CSame K-type probe reads correct +25.6°C now.Thanks for watchingP.S.Used gear:Calibrated Keithley 2001 Multimeter (5.FEB.2014)Keithley 2002 Multimeter (10.APR.2007)Calibrated EDC MV106 DC Voltage standard +-30ppm/°C (8.FEB.2014)Calibrated Keithley 2400 Sourcemeter (14.JAN.2014)
I need to know what Heathkit VTVM uses a 12BH7A,6AL5 tubes. - Page 1
Forum section: electronics / testgear

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 05, 2014, 04:59:25 am
content: Hi.Anybody knows what model of old heathkit VTVM uses a 12BH7A and a 6Al5 tubes?I bought a clone,with bad resistors on the attenuator(Switch range),I can not see what's written on them,think its really a heathkit clone,the display is the same as heathkit V6.

author: staxquad
author_rank: Frequent Contributor
timestamp: June 05, 2014, 05:45:32 am
content: They probably substituted a 12bh7a for a 12au7Lots of Heathkit VTVM models use 12au7 and 6al5 tubes

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 05, 2014, 06:56:37 am
content: staxquad maybe you are right,I see that 12au7 is the same tube!

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 05, 2014, 07:03:09 am
content: This diagram is the heathkit V6,I looked carefully and saw that is equal to my.VTVM are great devices.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 05, 2014, 07:08:42 am
content: Quote from: SAUL BRITTO on June 05, 2014, 07:03:09 amhttp://www.mzentertainment.com/technical_archive/heathkit_vtvm_v6_schematics.gif

author: kc9qvl
author_rank: Regular Contributor
timestamp: June 06, 2014, 03:18:23 am
content: My Knight vtvm uses the basic same parts and schematic.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 06, 2014, 03:04:12 pm
content: Wow!!I have a knight, but it fell off the bench and broke the switch range,was lucky(Not so much),my tubes are good and needle.I will try to fix this, but, know is not so easy.

author: Computeruser
author_rank: Regular Contributor
timestamp: June 06, 2014, 11:21:54 pm
content: I have an assembly manual for a Heath kit IM-11 VTVM from the mid 60's that uses 12AU7a and 6AL5 tubes.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 07, 2014, 04:56:39 am
content: Quote from: Computeruser on June 06, 2014, 11:21:54 pmCan you send me a copy? I will be very thankful!

author: Computeruser
author_rank: Regular Contributor
timestamp: June 09, 2014, 01:01:12 am
content: Best thing to do is google Heathkit IM 11. Here is a link I found with the schematic.http://www.heathkit.nu/heathkit_nu_IM-11.htmlMy manual is the original manual which I wish to keep.

author: SAUL BRITTO
author_rank: Frequent Contributor
timestamp: June 10, 2014, 02:30:09 am
content: Quote from: Computeruser on June 09, 2014, 01:01:12 amThank you!!!
Soft case for Flir E4 / E series - Page 1
Forum section: electronics / testgear

author: stefandz
author_rank: Contributor
timestamp: June 09, 2014, 11:55:55 am
content: Hi everyoneI'm guessing plenty of people on the forum now have their very own Flir E4 upgraded to E8I use mine extensively and it's growing popular with mates, which frequently means throwing it in a rucksack and taking it out and about.Since there's no way I'm walking down the street with the big Flir lunchbox that came with it, and no way I'm paying big bucks for an official soft case, I was wondering if anyone had found a reasonable soft case source for their cam? I tried Google, AliExpress and eBay - best I could find so far wasthis, but it seems clumsy and overkill.Anybody found something that fits the bill?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 09, 2014, 01:03:57 pm
content: Problem is it's a bit of a weird shape to find anything similar - how about a large, thick sock?

author: stefandz
author_rank: Contributor
timestamp: June 09, 2014, 01:07:44 pm
content: Strangely, it wouldn't be the first time - I used to use a ladies pop-sock to cover my first MP3 player... The E4 is pretty well protected itself so maybe that would be enough. I really just want something to cover the lens in the unlikely case that the shutter opens or I leave it open when I throw it in the bag.Wasn't expecting you to be the first to answer Mike, I could have bothered you outside of the forum!
Tektronix 2465B vs 2247A - Page 1
Forum section: electronics / testgear

author: Electro Fan
author_rank: Super Contributor
timestamp: June 03, 2014, 02:52:47 am
content: I've been reading the manual but maybe I've missed some setups for the 2465B. Is there a way to get the voltage to display (other than using manual cursors) through the measurement button so that when the voltage displays it doesn't change the time base setting? Also, when selecting the cursors is there a way to make the cursors automatically track changes in voltage? (On the 2247A the time base doesn't change when invoking the voltage measurement and it's possible to make the cursors automatically track changes in voltage.) Thanks

author: Electro Fan
author_rank: Super Contributor
timestamp: June 04, 2014, 03:54:15 am
content: Must be someone with a 2400 series scope out there that knows something about these features/functions...?Thx

author: w2aew
author_rank: Super Contributor
timestamp: June 04, 2014, 03:40:32 pm
content: Quote from: Electro Fan on June 03, 2014, 02:52:47 amYou're not missing anything. You have to remember, these were not digitizing scopes. The automatic measurements in the 246xB series were analog measurements - the scope had to change the timescale to show a few cycles only, and the vertical scale so that the internal analog measurement system could make its measurements. Pretty high-end stuff for 1989 analog scopes.The 2247A included a feature called Smart Cursors, where the cursors would "show you"where the automated measurements were made, and to track the voltage (and trigger level, etc.). To my knowledge, this smart cursor feature was never added to the manual cursors on the 2400B series.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 04, 2014, 03:54:32 pm
content: QuoteThat's true although the 2252 has a hardcopy facility which means it must have a digitiser - apart from this the 2252 is identical to the 2246. I haven't looked to see if the 2246 also had an ADC used for the measurement system.

author: Electro Fan
author_rank: Super Contributor
timestamp: June 04, 2014, 11:53:06 pm
content: Quote from: w2aew on June 04, 2014, 03:40:32 pmThanks - just wanted to confirm I wasn't overlooking those features/capabilities if they were buried deeper somewhere in the menus. The 2467B is a very cool scope with excellent performance (400MHz, MCP display, the way the A and B sweeps work, and more) but the 2247A offered some seriously nice/useful features if you could live with 100MHz. The Tektronix product teams really did great work with both the 2400 and the 2200 series and these two models are definitely very cool.

author: ctm2matman
author_rank: Newbie
timestamp: June 09, 2014, 06:27:31 am
content: Tektronix made the 4662 plotter that allowed a screen copy from terminals/instruments such as the 4051 and 4052 graphics computers which utilized bi-stable storage CRTs. Digitization was not necessary. These were fully analog displays.
Fluke 87V LEAD alert - Page 1
Forum section: electronics / testgear

author: MITTS
author_rank: Contributor
timestamp: May 31, 2014, 11:51:10 pm
content: Sorry if this was covered before but couldn't find a match on the problem.On my 87V I get a very intermittent alert about the lead on the screen. I seems the measurement on various selections works fine but the display flashes the lead alert and the buzzer sounds. I use Fluke leads and seem ok. Could this be a simple maintenance issue with the sockets? TIA

author: Excavatoree
author_rank: Frequent Contributor
timestamp: May 31, 2014, 11:57:12 pm
content: I'm sure one of the Fluke repair experts will reply, but I do believe that dirty sockets can cause this problem. I know the "canned gas" dusters can help clean the jacks, but I'm sure the experts will have some good advise.

author: Rory
author_rank: Frequent Contributor
timestamp: May 31, 2014, 11:59:14 pm
content: If you have a plug in the mA or A jack and place the knob in any V measurement mode the meter will give you the LEAD alarm until you either remove the plug or change the mode to an A measurement setting. Is it intermittent in the V ranges or just appears when you switch the meter through the V and diode settings on the way to the A settings?

author: MITTS
author_rank: Contributor
timestamp: June 01, 2014, 03:46:14 am
content: yes it is a intermittent fault when the leads are in the correct sockets for the measurement selection and i rarely take mA or A measurement through my leads in those sockets. I use a i200s for current. It has only ever happened to me when the leads are plugged into the com and v sockets and seems to starts as soon as the meter is turned on.

author: Rory
author_rank: Frequent Contributor
timestamp: June 01, 2014, 04:15:04 am
content: Not the first time this question has been asked on the forum.The answer from below: blast out the dirt with compressed air.Hope this helps.https://www.eevblog.com/forum/chat/fluke-87v-displaying-%27lead%27-and-sounding-beeper-when-nothing-is-plugged-in/

author: VK5RC
author_rank: Unknown
timestamp: June 01, 2014, 07:37:32 am
content: Interestingly my 87v came with dust covers for the non used holes, must be a relatively common issue. No problems yet. :-)

author: Rory
author_rank: Frequent Contributor
timestamp: June 01, 2014, 06:32:04 pm
content: Quote from: VK5RC on June 01, 2014, 07:37:32 amSo did mine. But they don't seem to fit very well.

author: MITTS
author_rank: Contributor
timestamp: June 02, 2014, 01:06:41 am
content: great Thanks GuysIll try cleaning the jacks with the cue tip and alcohol since Ive tried blowing them out before.

author: MITTS
author_rank: Contributor
timestamp: June 09, 2014, 05:18:16 am
content: For future if someone else is searchinghttp://youtu.be/rCXPiN09tkg
ATTEN ATF20b mainboard full failure - Page 1
Forum section: electronics / testgear

author: mbdemello
author_rank: Newbie
timestamp: June 01, 2014, 04:17:34 am
content: Hi fellows!! I have an ATF20b since 10/2012 and yesterday it was running well when the (both, A and B) output dead. The control panel is working well but there is no output, neither a little rf noise or some DC level, nothing!! I checked the mainboard's DC supply (5V, +/- 15 and others) and it seems ok. I checked the mainboard outputs (A and B) and they are completely dead too!The only information about the conditions during the failure is that it happened when I was using the "A" output , in open circuit (no load) at 10.0 MHz.Someone already heard about this kind of failure?We don't have Atten service here in Brazil, do you know if is possible to find a ATF20B's circuit diagram or any kind of information?Thanks and regards!=====Some (bad) News!Today, after several tests, I realized there was no clock in the AD9708AR, then the FPGA was not sending the clock signal. Next I turned off the generator, freezed the FPGA (using a freezing spray), turned it on, the FPGA put the 100.0 MHZ clock in the D/A Converter, the generator works fine for three or four minutes and fail again. I repeated this procedure three times and then I think there is no doubt the failure is in the FPGA Cyclone I! And now? What is you opinion? Do I need to replace the entire mainboard?Thanks again!

author: (In)Sanity
author_rank: Regular Contributor
timestamp: June 09, 2014, 12:45:39 am
content: Sorry to hear your ATF20b died. Might I suggest an easy remedy to your pain and suffering ? It would involve finding the nearest round receptacle of a proper size removing it's lib and forcefully tossing the AT20b inside. Follow this process with proper closure of the lid and set down on the curb for collection. After that process is complete I would suggest finding a better suited alternative.I'm thinking I may need to do do some ESD testing on the one I have to see how well it conforms to industry standardsI at least manged to get an accurate clock out of it by replacing the 20 mhz clock can with an adjustable TCXO.Jeff

author: Fraser
author_rank: Super Contributor
timestamp: June 09, 2014, 02:06:22 am
content: I would consider dry solder joints as a possibility before scrapping the unit. Some decent liquid flux and the application of a hot air station output may rectify the situation for you. I am meeting dry points in FPGA and especially BGA formats a lot at the moment. Most have failed as the IC temperature rises, and rectify themselves when freezer spray is applied.Worth a try before giving up on it.Aurora

author: (In)Sanity
author_rank: Regular Contributor
timestamp: June 09, 2014, 04:28:19 am
content: It's a shame really, the hardware isn't really all that bad. The non upgradable firmware just cripples an otherwise usable device. It could be a decent device if it wasn't for the terrible coding behind it. Ohh well.In any event, might as well look for solder joint problems, certainly wouldn't be the first time a product had that problem.Jeff
How does your lab look like? - Page 1
Forum section: electronics / testgear

author: davorin
author_rank: Unknown
timestamp: June 08, 2014, 10:00:57 pm
content: Long time ago a learned electronic design, switched then over to internet and network technology and finally come back to my roots....Also a reason for this is that currently internet/network and electronics are merging nowadays...So I'm asking out of curiosity what your electronic lab looks like by means of equipment......and what I am currently missing (o;So far my electronic lab contains:2 * HP6632B power supplied (2 more to come ;o)1 * LeCroy 9354AL1 * Philips PM35851 * HP3456A (1 more to come)1 * HP8904A (currently in repair)1 * Fluke 6060A1 * Selfmade USB to GPIB adapter, based on Microchip PIC18F2550, total cost around US$ 15.Anything I'm missing? (o;

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: June 08, 2014, 10:16:13 pm
content: You started this threadafterreplying to the other thread that's exactly the same?

author: davorin
author_rank: Unknown
timestamp: June 08, 2014, 10:19:57 pm
content: Aah, I see the problem now...I wrote a new post....and suddenly it disappeared...but apparently it was moved to another one (o;
Agilent 6632B - CAL DISABLED - Page 1
Forum section: electronics / testgear

author: Bazillus
author_rank: Newbie
timestamp: June 08, 2014, 09:02:16 am
content: Hi,I just started calibrating my 6632B units on my own and it worked perfectly fine for voltage and protection voltage calibration.However, when continuing with the current calibration (page 61 in the user's guide), I get the message "CAL DISABLED" when trying to enter the "CAL CURR" menu.The hardware calibration switch is enabled - otherwise I would not have been able to enter the successfully completed voltage calibration.Did anybody encounther this error message or does anybody know how to enter current calibration? Unfortunately, the user's guide does not give any hint ...Just for completion the push-button sequence with which I tried to enter the current calibration:- Output --> *RST --> Enter- Output On/Off to enable the output- Shift Cal --> CAL ON --> Enter- Shift Cal --> CAL CURR --> Enter- Message: "CAL DISABLED"ThanksMichael
Is it possible to get a display for the 33120a? - Page 1
Forum section: electronics / testgear

author: reportingsjr
author_rank: Contributor
timestamp: April 24, 2014, 08:52:19 pm
content: Hi,I tried searching for quite some time and short of calling agilent I haven't been able to find a replacement display for the 33120a.I found the specific part number is 33120-66502, but on parts.agilent.com it is just listed as obsolete.Obtainable, or unobtanium?Thanks!

author: vaualbus
author_rank: Frequent Contributor
timestamp: June 04, 2014, 10:16:41 pm
content: I'm also search for the display.

author: mimmus78
author_rank: Unknown
timestamp: June 06, 2014, 10:48:49 pm
content: I have a Keithley 2000 VFD spare but not this one ...

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: June 06, 2014, 11:02:49 pm
content: I saw some 34401a displays on an auction the other day. I had wondered if it was possible to use one of those even if the annunciators don't match.I didn't bother to check if pinouts or the physical sizes matched. Maybe possible as a last ditch choice?
How to combine channel signals Rigol DS1000E? SOLVED - Page 1
Forum section: electronics / testgear

author: RobRob
author_rank: Newbie
timestamp: June 06, 2014, 03:37:55 pm
content: [SOLVED: See posts below]I've searched the manual and the web but cannot find how to combine the oscilloscope's two channels into one waveform. Is it possible with the Rigol DS1000E? If so how do I do it?I'm trying to sample two stages of a guitar amplifier, invert one signal then combine them so I can see distortion more clearly.Thanks in advance,Rob

author: Creep
author_rank: Regular Contributor
timestamp: June 06, 2014, 03:47:18 pm
content: Now i don't own a DS1052E, but I'm pretty sure there should be a math addition function on the scope. I think that's exactly what your looking for.

author: Wytnucls
author_rank: Super Contributor
timestamp: June 06, 2014, 03:53:30 pm
content: The Math function will do it for you:

author: RobRob
author_rank: Newbie
timestamp: June 06, 2014, 04:34:08 pm
content: It does have a math 'add' function but that just gives a number of the instantaneous Channel 1 + 2 value. I would like to see the combined waveform on the scope.

author: Wytnucls
author_rank: Super Contributor
timestamp: June 06, 2014, 05:16:41 pm
content: Watch Alan's video here, with waveforms on his Tek scope. The same can be done on the Rigol.

author: RobRob
author_rank: Newbie
timestamp: June 07, 2014, 12:35:48 am
content: Thanks guys for the quick help. I was confusing the 'Measure' feature with 'Math' and the Math A - B function did exactly what I needed.Thanks again,Rob
Rigol DP832 Power supply back in stock - Page 1
Forum section: electronics / testgear

author: tequipment
author_rank: Regular Contributor
timestamp: June 06, 2014, 04:23:17 pm
content: After 6 months we just got a bunch of the DP832's in. All are sold expect for 18.This is not a shameless plug because they will sell out in the next few days but I thought I would let the EEVblog members get 1st crack at the stock we have.http://www.tequipment.net/RigolDP832.htmlI have 18 left as of this moment.All back orders are filled or are shipping yesterday/Today/Monday.ThanksEvan CirelliTEquipment.NET

author: miguelvp
author_rank: Super Contributor
timestamp: June 07, 2014, 07:47:38 am
content: just for clarification because I'm not looking into getting one, but are those 18 DP832 clear of this problem?https://www.eevblog.com/forum/blog/eevblog-512-rigol-dp832-bad-design-investigation/

author: Rigby
author_rank: Super Contributor
timestamp: June 07, 2014, 07:51:44 am
content: Yes. I ordered mine from there 6 months ago, and received it a week later. It does not have the regulator issue.

author: tequipment
author_rank: Regular Contributor
timestamp: June 07, 2014, 04:27:59 pm
content: Yeah that are the fixed design. . We had a lot of back orders. These were just what was left. 12 left as of today.ThanksEvanTEquipment.NET
Any info on an Siemens PCM P2014 System Analyzer? - Page 1
Forum section: electronics / testgear

author: theelectronicegg.com
author_rank: Newbie
timestamp: May 30, 2014, 06:22:05 pm
content: Hi,there is an "Siemens PCM P2014 System Analyzer" curretly on ebay germany. It looks interesting and at least worth a teardown... but i can't find ANY info about it... don't know any specs or what it's usefull for...It did not sell for 30€ (twice)... the new auction starts at 25€...Has anyone got a clue for me?Thanks

author: david77
author_rank: Frequent Contributor
timestamp: May 30, 2014, 06:51:37 pm
content: All that Siemens stuff that turns up on ebay Germany is probably old stock either from Deutsche Bahn (German Rail) signaling department, from Deutsche Telekom (phone network) or from the German army. They are probably selling off all the old gear that was used for analog phone lines. Siemens was the usual supplier for telephony gear and related T&M in the good old days of state run phone networks here.I don't know either what that PCM2014 thing was used for, but I'd guess it had something to do with frequency multiplexed phone lines or, more likely, a later digital variant thereof.

author: 128er
author_rank: Regular Contributor
timestamp: May 30, 2014, 07:32:48 pm
content: David77 is probably quite right. PCM is written all over this instrument. I guess it stands for Pulse Coded Modulation. And it has something to do with digitizing analog phone lines. With this thing you can probably generate bit patterns, or measure the jitter of your signal. I have a similar device from Wandel & Goltermann, name is "SF-60, PDH/SDH transmission and jitter analyzer". But the SF-60 is only for digital networks.For 25€ it is worth to take a look inside. But i don't think that you have great benefit from using it.

author: 128er
author_rank: Regular Contributor
timestamp: June 06, 2014, 06:34:34 pm
content: The auction is over. Did you buy it?
Fluke 713 Pressure Calibrator Teardown - Page 1
Forum section: electronics / testgear

author: Chipguy
author_rank: Unknown
timestamp: June 05, 2014, 10:02:19 pm
content: Hi,welcome to teardown ThursdayUnfortunately I still don't call a decent HD camera my own but I want to share my teardown of a Fluke 713 pressure calibrator.Here you can find the datasheet of the pressure sensor, at least a compatible one.http://www.ge-mcs.com/download/pressure-mems/920-303B_LR.pdfThe circuit in the Fluke is basically the one in the datasheet plus a differential amplifier so the entre circuit becomes a instrumentation amlifier like this:http://upload.wikimedia.org/wikipedia/commons/thumb/e/ed/Op-Amp_Instrumentation_Amplifier.svg/400px-Op-Amp_Instrumentation_Amplifier.svg.png.It is a pretty straight forward design from 1997. I bet today's Fluke 713 will look different inside since the 20 bis ADC is not available anymore.Here I have marked some parts of the circuit. Here the Current loop amplifier, pressure sensor and multiplexer.Here the Instrumentation amplifier and the excitation circuit.Below is the picture gallery I have shot. Enjoy.Again, sorry for not having done a video on this. I should get a camera for that, I know.

author: EEVblog
author_rank: Unknown
timestamp: June 06, 2014, 12:14:50 am
content: Awesome work & photos

author: TimNJ
author_rank: Super Contributor
timestamp: June 06, 2014, 04:00:45 am
content: Yes, I agree with Dave. Awesome pictures!

author: Chipguy
author_rank: Unknown
timestamp: June 06, 2014, 05:47:30 am
content: Thanks