Need recommendation:  Keysight u1252b or u1282a or other? - Page 1
Forum section: electronics / testgear

author: 25 CPS
author_rank: Frequent Contributor
timestamp: June 01, 2020, 09:22:58 pm
content: I've been looking over the datasheets for the Keysight u1252b and u1282a multimeters and either I'm completely missing the obvious that's staring me in the face and I just can't see it or there's an omission: The built in square wave generator. What's the amplitude of the output?I'm working on some older PWM systems now and the square wave output would be handy to have as a convenient excitation source but I need TTL levels. I'm open to considering alternate equivalent meters from Fluke, etc. or a ruggedized handheld function generator, too, so recommendations and information about all three possibilities is most welcome. Thanks!

author: petrinch
author_rank: Contributor
timestamp: June 02, 2020, 02:57:45 am
content: U1252B=0-2.8vhttps://www.keysight.com/us/en/assets/7018-01428/data-sheets/5989-5509.pdfU1282A=0.2.2v :https://www.keysight.com/us/en/assets/7018-04867/data-sheets/5992-0847.pdf

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 02, 2020, 12:39:22 pm
content: I just tested my U1252B output (the battery is at about 2/3 charge) and the output was 2.8V pk-pkThat should work for 5V and 3.3V TTL

author: 25 CPS
author_rank: Frequent Contributor
timestamp: June 03, 2020, 05:11:35 pm
content: Quote from: petrinch on June 02, 2020, 02:57:45 amThanks. I had been reviewing the data sheets and missed it completely for the u1252B and the entry for the u1282a confused me with the line that said "Fixed + 2.2 V".Quote from: Gandalf_Sr on June 02, 2020, 12:39:22 pmGreat, that's good to have an actual measured output.I'm beginning to think either the square wave outputs on these meters either aren't in frequent use or the people who do use this function just hook it up and turn it on and accept that it works with whatever they're working on without getting too deeply worried about the specifications of the output or the input device they're driving with it since comprehensive information seems to be hard to come by.I'll probably pick up one of these meters but I may also add a ruggedized function generator if I can find something suitable that way to my portable test kit since it'd be useful to have sawtooth ramp waveforms as well for some applications. Honestly, I thought my basement was getting bad for equipment and now it looks like my truck is heading the same way...

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 03, 2020, 06:13:49 pm
content: Quote from: 25 CPS on June 03, 2020, 05:11:35 pmThe U1252B is a serious meter, mainly in terms of accuracy and maybe overkill if all you wanted to do was generate a square wave with a variable pulse width. I got mine NOS from a guy on eBay so I paid nowhere near the list price. They sometimes come up on eBay but I don't see any cheap ones right now.I have a couple of Aneng 8008s that generate a 3.3V pk-pk square wave but they (annoyingly) center the signal on zero volts so it's kind of useless for driving logic as they are +/- 1.65V. I suspect there are some cheaper meters that do what you want.

author: 25 CPS
author_rank: Frequent Contributor
timestamp: June 03, 2020, 08:27:16 pm
content: Quote from: Gandalf_Sr on June 03, 2020, 06:13:49 pmThere probably are cheaper meters that'll pop out a square wave but it's going into a portable service kit that I use on radio and TV broadcast installations plus electric railway traction systems, so I need a serious meter with serious performance and serious safety specs. To a degree, the u1641a insulation tester I already have fills many of those slots but doesn't have a 10A current range and doesn't have the ability to generate a PWM waveform for use in the latter situation. The reason why I was leaning towards those two Keysight models specifically is because they'd integrate nicely with the u1641 and u1213 which is actually very capable as a DMM in general despite being a clamp meter, and wireless BT adaptors and logging software on my tablet and laptop, along with the workflows built around that.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 03, 2020, 09:19:46 pm
content: I figured that you probably had justification for a great meter. Right now you can buy theU1252B New from the Keysight eBaystore for $437 shipped.

author: 25 CPS
author_rank: Frequent Contributor
timestamp: June 03, 2020, 11:04:59 pm
content: Quote from: Gandalf_Sr on June 03, 2020, 09:19:46 pmThanks for the suggestion. I have bought from Keysight’s eBay store before and been happy so that was one of the first places I looked when I started researching this but there’s a surprise head scratcher lurking there: The listing for the u1252B is a ships only to USA item. I just spent a few minutes browsing around their eBay store and all the items I looked at that are in “New” condition are USA only for shipping but the “Used” refurbished equipment is shipped world-wide.My speculation, and it’s really just a guess, is that Keysight is protecting their international distributors and not undercutting them on new equipment sales via their own eBay store but that concern wouldn’t apply to refurbished units, which is why I was able to buy some older Agilent equipment there without any problems. Unfortunately, that rules out getting either a u1252b or u1282a from there since even using a workaround like shipping to one of my friends in the states and then picking it up whenever we get together next is off the table with the border closed, so I’m going to have to look around and see what other deals there are out there.You’re right about the Keysight DMMs being a great meter. They are fine machines. Most of what I have on my bench at home is older HP and some newer Agilent and Keysight gear with the exception of Tek for scopes. I wasn’t expecting to put together such a comprehensive mobile toolkit though given my bench capability at home and in the shop at work but shifting job requirements, a bit of freelance work, and volunteer work have all added up towards needing to have a decent set of test equipment to take on the road and junk drawer Canadian Tire DMMs only take you so far. They’re good for lending out since it’s no great loss if one gets damaged or doesn’t come back, but once you need to be certain in the results of measurements or that it won’t explode in your hand if a transient rips down the line while you’re working on a large piece of equipment, you really do need top tier equipment for sure.