Unboxing + Quick Test of a New Old Stock Agilent 34401A - Page 1
Forum section: electronics / testgear

author: Traceless
author_rank: Frequent Contributor
timestamp: February 09, 2025, 07:59:20 pm
content: thanks to@bdunham7who recently found an auction of new old stock meters on ebay andmentioned the auction the the Buy/Sell/Wanted sectionI had the opportunity to grab a nice new old Stock 34401A. It indeed arrived mint in box.Today I finally found some time to set up the meter on my bench and do some quick tests. After a 10 min warmup I hooked the meter up to my bench supply set to 5V and a 0.001% 10kOhm resistor. I was really curious if after 10+ years in storage the meter would still be accurate - I have to say I'm impressed see for yourselves.Thanks again to bdunham7 for letting us know about the auction.

author: bdunham7
author_rank: Super Contributor
timestamp: February 12, 2025, 01:32:51 am
content: I'm still waiting for my commission check from that seller. I'm beginning to think it's not coming!Seriously, great to see some EEVBloggers get that meter of their dreams. A couple of tips for those of you that are new to them.1. You have to learn the menus. Read the manual and figure out how to change the resolution, NPLC, input impedance, etc.2. A pretty standard serial-to-USB cable will get you connected to a PC pretty easily and give you another digit to boot. It's a bit noisy, but with some averaging it works.3. The default configuration on power up is 5.5-digit 10M input. For accurate measurements you want 6.5-digit 100NPLC (slow) and high input impedance.4. If you get the serial cable and get it set up, there's a list of enhancements you can make to the meter. There is a power-up configuration setting that will become available as well as a bunch of others. I have short text file with instructions but it is best if you find the EEVBlog thread on this subject and read it. Great care is required as I don't know the consequences of mistake. There is a temp option as well, but it is pretty worthless with a thermocouple because there's no cold-junction compensation. A platinum RTD should work though.5. Two members have written software that works with these meters. One is byHKJand is called TestController, it's what I use. The other I can't find right now, it was HP-specific. Look for these.

author: Hydron
author_rank: Super Contributor
timestamp: February 12, 2025, 02:01:21 pm
content: I do find the temperature option quite useful for RTDs. More info on the hidden features is in the thread:https://www.eevblog.com/forum/testgear/hp-agilent-34401a-hidden-menu/?allIf you activate the option for the settings recall thing then you can start up in fast 6-digit mode every time (at the cost of about 1 second longer boot time) and not worry about burning in 5 digits more than the 6th.

author: SHF
author_rank: Regular Contributor
timestamp: February 12, 2025, 06:54:53 pm
content: I also have a device from this dealer and can confirm that the calibration is still top notch

author: Traceless
author_rank: Frequent Contributor
timestamp: February 12, 2025, 07:11:53 pm
content: Quote from: bdunham7 on February 12, 2025, 01:32:51 amToo bad you have definitely earned a commission IMO =).Thank you for pointing out all those hidden options/upgrade possibilities I'll take a closer look at those during the coming weekends. The limited use of the temperature option is not a big deal - I still have the 34465A, a Brymen BM869s, and two of the cheap Harbor-Freight-Style meters which can all measure temperature.Also thanks@Hydronfor linking the related thread.Out of curiosity - is there any age related issue/series defect known on the 34401A meters that I need to check for? I remember vaguely that some of the older Keithley 2000 series DMMs from the 1990s/2000s had bad capacitors which are almost guaranteed to spill their guts over the PCB. IIRC it was even worse because some of those where crucial for the input voltage regulation and cause most of the ICs to blow up if not replaced in time. The Agilent unit I have here seems to have been built in 2013 or 2014 (The factory calibration sheet is dated 2014).Quote from: SHF on February 12, 2025, 06:54:53 pmNice thanks for reporting and congratulations to your new meter.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2025, 09:12:09 pm
content: https://www.eevblog.com/forum/testgear/hp-34401a-standalone-software/