Agilent 34450A or HP 34401A ? - Page 1
Forum section: electronics / testgear

author: octal
author_rank: Contributor
timestamp: May 31, 2025, 05:39:18 pm
content: A friend is offering to sell me an Agilent 34450A DMM for €300. Is this a good deal? Anyone here has experience with the 34450A or thoughts on whether I should go for it? or should I go for an HP 34401A (for almost same price) (both units are in very good shape and good conditions - all buttons ok, display is ok on both and connectors also works perfectly)

author: TheSteve
author_rank: Unknown
timestamp: May 31, 2025, 05:44:21 pm
content: 34401A - the VFD isn't as pretty but it is a much better DMM. The OLED display in the 34450A will fail sooner or later.

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: May 31, 2025, 05:45:17 pm
content: both are pretty good metersone is older but 6,5 digitsother is newer but 5,5 digitsIn older ones you often need to replace the display, keypad, etc - good idea to ask owner what was already made - with new VFD display or in good condition it is a dealNewer usually may need that laterOf course I assume that both are functionally and metrologically OK

author: octal
author_rank: Contributor
timestamp: May 31, 2025, 05:53:44 pm
content: Quote from: kmoonwalker on May 31, 2025, 05:45:17 pmBoth are OK, and the 34401A display is in excellent condition (the attached image does not render it justice, it's really bright)But it's the old model, I don't know if it can be easily repaired or not (comparatively to newer models)

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: May 31, 2025, 06:00:12 pm
content: well it has like 30 years or so but there are parts for it on ebay - and for that fraction of new one price well it is not destined to be with you for ever and everthose meters are both not bad quality or something - they are decent made - perhaps except oled that tends to fail faster than VFD but friend of mine has one of those new series meters over 10 years now and uses it every day and screen is OK - two in lab nearby failed after 4 and 6 years but there was some oled screen from ebay, too and working now (still they are younger, Keysight branded).

author: coromonadalix
author_rank: Super Contributor
timestamp: May 31, 2025, 06:05:40 pm
content: the old vs the new 34401a is mostly the vfd drivers / front panel pcb, you can not upgrade the old with new vfd drivers / front panel pcbmaybe just maybe unless you reprogram all mcu FW and display FW ... witch i never heard ofas for analog they are mostly the same, they aged pretty well and are very stable on the reference part. And SV manual / schematics exists, 34450 notworth to check if all the supply lines are noisy or not, maybe just maybe some capacitors changes, aint broke dont touch it, and the vfd is bright100% vouch for the oldie 34401a, unless you grab a good deal on the 34410a or a 34411a, the 34450 nahi know is $ but i would save for slightly more modern like 34410a 34411a they are way faster on acquisition, and have lan and usb ports, sv manuals exists toosome may say k2000 series ....in the end it depends of your real needs, not just some dealmy 2 cents

author: octal
author_rank: Contributor
timestamp: May 31, 2025, 06:45:53 pm
content: Thank you for your detailed and insightful answer, much appreciated.@coromonadalixJust to clarify, it’s not only about getting a good deal. I've been using handheld multimeters for years: I currently own a Brymen BM869S, BM253, UNI-T UT61, and a few others like Aneng and Zoyi models, along with a portable OWON scope/meter combo.But this time, it's not about adding yet another multimeter to the collection. Lately, I’ve been working mostly on IoT devices, and I now need to perform precise, long-duration measurements — not just current consumption (otherwise I'd go for a Joulescope or Otii), but more general measurements, with good resolution down to the µA range, auto-ranging into the mA range, and the ability to log continuously for 3–4 days and export the data to a PC.From what I’ve researched, a proper bench meter seems like the most solid investment for that kind of use case.Regarding the 34401A — I’m still considering it, but I’m not in a rush and could stretch the budget up to around $600 for a more recent model if it’s worth it. I hadn’t really looked into the 34411A before, so I’ll definitely check that out now. As for the K2000 series, I’ve used a 2001 briefly in the past, but not long enough to really get a feel for it.Thanks again for your advice — very helpful!

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: May 31, 2025, 07:04:23 pm
content: if you need a standalone data logging also check what options are installed in newer oneolder one can store only 512 readings or so and for more you need a PC or some other data acquisition system34450 needs option to have 50k mem on boardYou maybe more suited with investing in more modern meter like DMM6500 or higher Keysight model (sadly over mentioned price point but totally different world in terms of what they can do)

author: octal
author_rank: Contributor
timestamp: May 31, 2025, 07:52:36 pm
content: I can use a Raspberry Pi or something similar to read data continuously from the multimeter, it's not a problem for me. With handheld mm I had the problem that they go to sleep (or auto-off), and that the battery cannot last more than 2 days in best cases.So, having huge or small memory is not problematic.PS. I have seen nice ("looking") units on ebay for arround $450 if 34401A new revision (those with round corner buttons). This is not so far from what I want to spend. I may have to add about $100 to $150 for calibration, but it still remains a good deal for such reputable device

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: May 31, 2025, 08:19:39 pm
content: just watch the measurements acquisition and transmission speed whatever you will be consideringI also agree with coromonadalix that it is better to get 6,5 than 5,5 model (myself I would) - better accuracy, etc (still it is not comparable to 465a or dmm6500) but for mentioned price it is a very very decent meter.if you are not in a rush then spend some time saving money and asking around - from time to time folks are changing not very ancient 6,5 to 7,5 digit meters and perhaps you may get an older Keithley or dmm6500 (which is a superb meter for home lab considering extra features it has) or higher accuracy 6,5 digits HP/Agilent or more modern Keysight with better price than on ebay.Regardless of what you will choose from those better meters any should serve you well (but any particular unit mileage and ownership cost may vary).Most of friends purchased one per 15-20 years when they upgraded to something more capable usually.And usual opinion after getting a first decent 6,5 digit one was "why didint I got one sooner"

author: coromonadalix
author_rank: Super Contributor
timestamp: June 01, 2025, 04:39:43 pm
content: you have good software developed and put here to do logging over long periods34410a would be better, and vs the 34411a it is just sampling speed who increase, unless you go to the less friendly no keypad L4411asure some hate vfd's but they where cloned for the 34xxx series, not for 8845 8846 or otherssure if you need graph and other things, that's another talk as written in the dmm6500 and up ... but $ is way highermaybe just maybe, you could use NI Pci cards for cheap prices in some cases .. but now you have a pc instead ?

author: tatel
author_rank: Frequent Contributor
timestamp: June 02, 2025, 04:05:44 pm
content: Quote from: octal on May 31, 2025, 07:52:36 pmAn all-red jacks 34401 with serial number higher than 3146A59641 should have the V2 display hardware and thus can have it replaced. They go usually cheaper... I very recently got one (all-red jacks too) with serial number US36013900 and it came with firmware 07-05-02 which, it seems, means there are also some hidden features that can be enabled. Any newer models probably won't give you more features aside black/red jacks and better looking -and younger VFD-, but take this advice with a grain of salt.The attached screenshot with backdating information is from edition 9 of the manual, August 2014You could have a look at this thread:https://www.eevblog.com/forum/testgear/agilent-34401a-revisions/msg2199660/#msg2199660After what you said, I think a 34401 will fit you quite well