Fluke 33X_A/B/D Owners Chime In - Page 1
Forum section: electronics / general

author: Vgkid
author_rank: Super Contributor
timestamp: January 20, 2017, 06:10:33 pm
content: I'm looking at possibly getting a Fluke 33X series calibrator. I know the D specced units are top of the line, but pricey .Internally what are the differences between them, and the lower specced B versions. I know the A versions tended to use mechanical choppers, and an externally ovenized zener.

author: VintageNut
author_rank: Frequent Contributor
timestamp: January 20, 2017, 06:22:15 pm
content: I have a 332A. It works well. It is quite a chore to calibrate. It was an early purchase in my volt-nut adventure.Since I have acquired two units of KVD and a lead compensator and two of the Fluke 731B, I feel that that 332A is redundant.I think that a better use of your rack space and money would be spent on a fluke 544X if you want a big bulky calibrator.One thing that the big bulky Fluke calibrators can do well is output a stable accurate high voltage, like 987.6543 volts. That is not easy to do with a most KVDs nor would I want to energize either of my KVDs with 1000 volts.Quote from: Vgkid on January 20, 2017, 06:10:33 pm

author: Dr. Frank
author_rank: Super Contributor
timestamp: January 20, 2017, 06:56:38 pm
content: Quote from: Vgkid on January 20, 2017, 06:10:33 pmD versions have the the most recent electronics - These preferable items are: MOSFET chopper amplifier, T.I. RefAmp oven (not the simple ovenized zener), 3 tunable decades, 4-4-2-1 scheme.Anyhow, also a 332B/AF may have these (w/o the differential voltmeter).Avoid the mechanical chopper type!I also recommend a Fluke 5440B/5442A over the 332/335, as it's 10 times better in any aspect, and has an auto-calibration feature.To calibrate a 332/335 , you need so much additional equipment, that the bill is smaller for the newer solution.Frank

author: Vgkid
author_rank: Super Contributor
timestamp: January 20, 2017, 11:35:51 pm
content: As much as I would like a 5540/2 that is way to much for me price wise. I don't think I could get one for under 300.Back to the 33x.Aside from the upgraded chopper/ more stable vrefs. Any other differences.Problems with these?

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 21, 2017, 02:49:35 am
content: I think I had a 332B. Boat anchor for very large boats and only a so-so unit. As said, it shines if you need the high voltage capability, but other than that I think a small KVD and voltage reference would be more useful, or at least get used more. I gave mine away and had to do a really good sales talk just to get somebody to carry it out of the basement.

author: VintageNut
author_rank: Frequent Contributor
timestamp: January 21, 2017, 03:29:34 am
content: Quote from: Vgkid on January 20, 2017, 11:35:51 pmAs Dr. Frank mentioned, what you need to calibrate a 33X costs more than a 544X.What exactly will you use the 33X for?

author: e61_phil
author_rank: Frequent Contributor
timestamp: January 21, 2017, 02:20:17 pm
content: I had a Fluke 343A and a KVD in the past. I never tried to calibrate the 343A (cause it is a pain). I used it as a very stable tuneable supply only and the accuracy was achieved in combination with a reference an the KVD.Now, I have a Fluke 5440B and I'm very happy with it. It is a pleasure to use the 5440B, it is more stable, much easier to calibrate (only 10V and 1V is needed) and you can controll it via GPIB. Therefore, you can automate a lot of measurements.Another problem I had with my 343A was drift after changing the setting. This happend every time I changed the output voltage. This was very anoying for fine tuning some voltages.

author: dacman
author_rank: Frequent Contributor
timestamp: January 29, 2017, 02:25:05 am
content: Common problems with the 33X series that I've experienced are with Electrolytic Capacitors, Switches, and Trim Pots. What I've used to calibrate one: Fluke 752A, Fluke 732B, Keysight 3458A, Variac, Clarostat 240C (for load and line regulation checks), and sometimes a Fluke 720A. The same equipment would actually be needed to verify the output of the 5440 series. (In other words, it takes less equipment to adjust the 5440 series, but to actually check the output for accuracy would require the same equipment.)NIST (USA) built an automated AC measurement standard circa 1980 using a Fluke 5440 series calibrator as the dcV source (and Holt Thermal Converters). It was used to calibrate the Fluke 792A when it came out. Someone I talked to at NIST considers the 5440 series more stable than the 5700A (and they are much more stable than the 33X series).

author: e61_phil
author_rank: Frequent Contributor
timestamp: January 29, 2017, 06:53:29 am
content: Quote from: dacman on January 29, 2017, 02:25:05 amOf course, a verfication on this kind of gear isn't done with a handheld DMM. But I think for private use it should be enough to do this whole verification only from time to time to be sure everything is working fine. Furthermore, I think for most people it should be good enough to verify the 5440B with a 3458A (depends on your calibration "targets").Quote from: dacman on January 29, 2017, 02:25:05 amI heard something simillar.

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2017, 02:03:43 pm
content: Quote from: Dr. Frank on January 20, 2017, 06:56:38 pmWow do they really make circuits with mechanical choppers in this level.Why one should avoid such? Limited lifespan?

author: dacman
author_rank: Frequent Contributor
timestamp: January 29, 2017, 02:15:03 pm
content: I'm not (much of) a hobbyist, but I sometimes want to chime in and point out the difference between what a hobbyist and industry does.

author: Dr. Frank
author_rank: Super Contributor
timestamp: January 29, 2017, 04:50:48 pm
content: Quote from: Vtile on January 29, 2017, 02:03:43 pmYep,chopper relays were often found in FLUKE 1960ties devices, alike in the differential VM, like 801/803.Later, in the 70ties, they had the optical choppers, with neon bulbs. These can be found in the 845A, and also inside the 335s differential amplifier.The relays, and the neons both have limited life span, and are unobtainium to-day.Therefore my recommendation to avoid these.Another problem with old 332/335 is the deterioration of transistors, i.e. their beta decreases.Several circuits fail fatally, due to this, especially the HV pre-regulator.Therefore, it is recommended to measure the beta of the transistors, and replace these by modern ones.Frank

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2017, 07:59:17 pm
content: Thank you wery interesting subjects. Now when I think it more I quickly scimmed early in this week a one chapter of old "electronics measurement and control" style book from 1972 where author actually mentions that mechanical modulator/demodulator is (at that time atleast) better than silicon since true turn off. Hmm.. Need to reread the chapter.Oh, the transistor deterioration, interesting stuff my first ballpark quess of "free radicals" (what were the movie.. can't get the line to my head) moving with current were partially right. I weren't aware of electromigration phenomenom (and the subject were on level of "might happen"), but it makes sense. I wonder if it is partially behind the tin whiskers.New interesting reading for a few nights.Sorry of my offtopic ramble.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 30, 2017, 08:54:30 pm
content: Never Say Never Again? Purge those free radicals?Seriously, how much do Si transistors degrade over the years? I measure a lot of devices in audio equipment and most seem to survive fine after 40+ years. There are a few well known exceptions that get noisy or leaky like the 2SC458, but AFAIK the US made stuff didn't seem to suffer from that.

author: Vtile
author_rank: Super Contributor
timestamp: February 02, 2017, 02:46:15 am
content: Quote from: Conrad Hoffman on January 30, 2017, 08:54:30 pmHaha, that it were.https://youtu.be/qOQc3NAsPcI?t=2m48sThe one IEEE document I quicly scimmed through on the subject did spoke something like that it is more rising problem with recent technology and ICs and processors than those 40+ year old transistors.. Now I suggest you take my words as a really poor abstract. Here is the IEEE article:http://spectrum.ieee.org/semiconductors/processors/transistor-aging

author: Dr. Frank
author_rank: Super Contributor
timestamp: February 02, 2017, 11:25:52 am
content: Quote from: Conrad Hoffman on January 30, 2017, 08:54:30 pmI stated a degradation of beta inside the 33x, not in general, and not U.S. semiconductors related..In my 332B/AF, I simply found several transistors, same designator with varying beta of > 100, and < 30 in another place, especially on high power PCBs.I conclude, that this degradation arises from higher heating / power in these places.Anyhow, this kind of mechanism is well known, I assume.In my unit, I think that too low beta blew the HV regulator on the long run.On my unit the current monitor was not sensitive any more, and I also found too low beta transistors there.So my recommendation, to check for possibly bad transistors.Frank

author: Henrik_V
author_rank: Regular Contributor
timestamp: February 06, 2017, 09:31:18 am
content: Just want to drop a note here, that I currently got my hands on two defect Fluke 335A for spare parts. No servo boards and incomplete housings. Dr. Frank gave me a hint what he thought it is worth, I got for a fraction. To good stuff for the scrap press. So known voltnuts can expect shipping costs and a little compensation.As a metrologist I like the voltnuts dicussions, but since I'm into acceleration, I don't really hunt for (sub) ppms, I leave that for my peers

author: guido
author_rank: Regular Contributor
timestamp: February 06, 2017, 05:00:33 pm
content: Hello Henrik,Any Null Detector boards available (A6A1 Null Detector power supply / A6A2 Null Detector Amp)?On my 335D the Null detector part is not working. Getting some spare parts might help here.ThanksGuido