A dream came true Today34401A Digital Multimeter, 6½ Digit DMM

[DavidAzulay5000]

A dream came true Today  in perfect condition
HP 34401A Digital Multimeter, 6½ Digit DMM

[Miti]

Are you sure it is 34410 and not 34401? Congrats anyway!

[coromonadalix]

LOL  it is an 34401a   not a 34410a   huge difference  loll

[DavidAzulay5000]

Are you sure it is 34410 and not 34401? Congrats anyway!

Sorry spelling mistake, it's from the excitement
I have been looking for this device for a long time
A friend sold it to me today for less than $200

[coromonadalix]

good deal  if it works ok   

[DavidAzulay5000]

good deal  if it works ok   

work perfect no erorrs
pass all test

[Miti]

Sorry spelling mistake, it's from the excitement
I have been looking for this device for a long time
A friend sold it to me today for less than $200

I totally get it. I bought one from a colleague for 150 CAD and I’m thinking of buying the second one for the same price. I can’t find a reason not to. 

[DavidAzulay5000]

 

Sorry spelling mistake, it's from the excitement
I have been looking for this device for a long time
A friend sold it to me today for less than $200

I totally get it. I bought one from a colleague for 150 CAD and I’m thinking of buying the second one for the same price. I can’t find a reason not to. 

.

[Swake]

These things go 3x that price on this continent.

[J-R]

I don't think the friends-pricing is valid for comparisons!

In my opinion, the 34401A is mostly good for accuracy & stability, but to capitalize on that you need to have it calibrated.  Usability is becoming a bit outdated compared to the new stuff on the market  Even something as simple as Min/Max is a pain in the neck.

[DavidAzulay5000]

I don't think the friends-pricing is valid for comparisons!

In my opinion, the 34401A is mostly good for accuracy & stability, but to capitalize on that you need to have it calibrated.  Usability is becoming a bit outdated compared to the new stuff on the market  Even something as simple as Min/Max is a pain in the neck.

Amazing device
In terms of calibration
I tested it compared to my Quadtech 1659 RLC DigiBridge
He is my standard in terms of accuracy
Indeed all the resistance of the resistors exactly
From 5 milli ohms to 100 mega ohms
The only thing I did to 34401A
This is a short calibration
I was surprised that the milliohm resistance measurement was accurate even with 2 wires

[NoisyBoy]

Then you are assuming the Quadtech is your reference standard, when did you last check its calibration?

The 34401A is capable of better than 0.01% accuracy in resistance measurement, which far exceeds the Quadtech spec of 0.1%.  So while what you do can verify whether it is in the ballpark, it is far from the calibration 3-R suggested.  As the full calibration also check on other functions beyond resistance as well.

However, many 34401A hold its accuracy well, perhaps that’s all you need, and that is perfectly acceptable. But if you need a 6.5 digit meter for high precision and accuracy, then I agree with 3-R that a full calibration is a good investment. 

I think annual calibration may be excessive for most hobbyists except the volt nuts, I personally would send a used meter for calibration, so i know I can trust its reading.  Especially if it has not been calibrated for a few years.

In any event, congratulations on your new meter. I have a couple, I love their silent operation and fast boot time.  But if you need to see MIN-MAX, then I think newer meters definitely have an advantage. 

Enjoy your new meter.  Outside of a calibration,I would also suggest a new VFD if you want the ultimate readability. 

[DavidAzulay5000]

Then you are assuming the Quadtech is your reference standard, when did you last check its calibration?

The 34401A is capable of better than 0.01% accuracy in resistance measurement, which far exceeds the Quadtech spec of 0.1%.  So while what you do can verify whether it is in the ballpark, it is far from the calibration 3-R suggested.  As the full calibration also check on other functions beyond resistance as well.

However, many 34401A hold its accuracy well, perhaps that’s all you need, and that is perfectly acceptable. But if you need a 6.5 digit meter for high precision and accuracy, then I agree with 3-R that a full calibration is a good investment. 

I think annual calibration may be excessive for most hobbyists except the volt nuts, I personally would send a used meter for calibration, so i know I can trust its reading.  Especially if it has not been calibrated for a few years.

In any event, congratulations on your new meter. I have a couple, I love their silent operation and fast boot time.  But if you need to see MIN-MAX, then I think newer meters definitely have an advantage. 

Enjoy your new meter.  Outside of a calibration,I would also suggest a new VFD if you want the ultimate readability.

this is all i need dont use MIN-MAX

[coromonadalix]

i had some of my 3x 34401a  meters checked  and 2 of them ended being calibrated,   but the cal facility  said they where on par /  within the specs 10-15 years later ....

i recapped 2 of them, and 1 of them had an clone vfd installed in it ........


now upped the game with an 34410a,  who got a new cloned vfd tooo

you have some software  here on eevblog  if you want to do some logging  ....

[DavidAzulay5000]

i had some of my 3x 34401a  meters checked  and 2 of them ended being calibrated,   but the cal facility  said they where on par /  within the specs 10-15 years later ....

i recapped 2 of them, and 1 of them had an clone vfd installed in it ........


now upped the game with an 34410a,  who got a new cloned vfd tooo

you have some software  here on eevblog  if you want to do some logging  ....

I know the software
Later I will install it on one of my computers that has a GPIB connection.

I am very pleased with the purchase
Usually all my measuring equipment I bought broken and repaired and calibrated after that.

This is one of the only devices I've purchased that is completely working.

He had another 34401A that I could have purchased much cheaper because it had a problem measuring resistor values less than 2 ohms and I did not purchase it even though it is very easy to fix it in the future I might purchase it as well because I really liked the performance of the 34401A .

I tested the 34401A today
in a 4 wire connection
for measuring resistances
of my VISHAY precision resistor collection
0.01%
And all the measurements were exact
I'm going to use it mostly for measuring short circuits.

That's why the milliohm resistor measurements were most important to me
On a daily basis I use my Quadtech 1659 RLC DigiBridge project
which is an amazing measuring device .

Its only problem is that the measurements are made on the 4-wire Digibridge fixture connector on the device
That means to measure anything you have to connect the component directly to 1659
Do you know how pleased I was that the 34401A
Gave me the same results as the 1659
that the 1659 I calibrated.
It is very easy to calibrate, you only need 4 precision resistors with specific values
24.895 ohms and  15 ppm
374.06 ohm 5ppm
5.9581 kilohms 22ppm
94.986 kilohms 280ppm

[J-R]

Totally understand if you only need certain functions and can also test the 34401A to verify it is accurate in those areas.  I have a DMM I'm debating getting calibrated, but have mostly been just using it for DC 0-10V, so...

The calibration data printout for my 34401A has a couple hundred data points.  An older device that has stabilized combined with at least a somewhat recent calibration + data is very nice to have.  It builds trust!

I recently picked up a new DMM with both the factory calibration and then a 3rd party calibration only a few months later.  The 3rd party didn't do any adjustments, just provided the data printout.  Well, that thing had drifted enough that the last digit is not really even worth looking at.  But still in spec.  And from a daily usability perspective, it's far better than the 34401A.

[DavidAzulay5000]

HP 34401A after zero calibration on all the Ranges

Resistor testing on some of my vishay precision resistor collection
0.05 percent
0.01 percent
2500 ohm
10 Kohm
5 Kohm
125 Kohm
1 ohm
100 milliohm
Etc. etc
Starting with resistors 5 milliohm ceramic resistors
Up to 100 mega ohm 1 percent resistors

[Wade2019]

Congratulations on owning the 34401A, which is the representative of the multimeter，Although I own three 34401A and one 34410, I am still very excited to meet 34401 for the first time

[DavidAzulay5000]

Congratulations on owning the 34401A, which is the representative of the multimeter，Although I own three 34401A and one 34410, I am still very excited to meet 34401 for the first time

i have 4 DMM

Quadtech 1659 RLC DigiBridge

HP 34401A

keithley 197A autoranging microvolt dmm

FLUKE 87

[DavidAzulay5000]

In order to check the accuracy of measuring DC voltages

 I built a precision voltage reference 5 volt

 Based on the linear technology LT6657AHMS8-5

Accuracy of 0.1 percent in regulation

PPM 0.5

The measurement voltage  5.000.73 volts.
Later I will build some more
I have too many V REF
To choose from my collection.
LTZ1000
LM399
LT1021 5V 7V 10V
TL1634 1.25V
LT6657 1.25V 2.5V 3V 5V
LT6658

And lots of other models.
I usually dont like to use them because I like to collect Linear Technology components.
Some people collect stamps
I collect components.
I have about 20 models of their voltage reference

[PartialDischarge]

i had some of my 3x 34401a  meters checked  and 2 of them ended being calibrated,   but the cal facility  said they where on par /  within the specs 10-15 years later ....

Same, I have a 34401 not calibrated in probably 15 years, checked it with a new DMM6500 and they only differ a bit in the last digit

[Fungus]

Same, I have a 34401 not calibrated in probably 15 years, checked it with a new DMM6500 and they only differ a bit in the last digit

It's almost as if they were designed for that... 

[DavidAzulay5000]

Perfect 10 10.000.00V

 Another precision volt reference I built
 Based on the Linar Technology IC

 LT1021bch-10

 Exactly 10.000.00 V
https://www.youtube.com/shorts/Tx1SPPJ5NDI

[MathWizard]

These things go 3x that price on this continent.

Yeah thats a great price, they never go that low on ebay. I think when I got my SDM3065X, all the similar used 34xxx and Keithley's were about the same price, and more. I have no regets the 3065x is great for me, but someday I'd like to see the difference, the top brands make.

[NoisyBoy]

You would not want to compare a modern meter UI and display against a vintage meter like a 34401A, when you do your comparison, you should do it against a 34461A.  It is not fair to compare a 30+ year old design to a modern equipment. 

While I love the quiet operation of the 34401A, quick boot time, and stability, it is no match with modern meters without logging its output to the PC.  So if you are looking at capturing and displaying more than a single point of of measurement, or trying to see trends, or trying to get dual displays such as voltage and frequency, your life would be so much easier with a modern meter. 

[coromonadalix]

you have some software(s) who will give this old veteran life extension   lolll

[jerryk1234]

I just got one of these yesterday.  Normal Ebay price.  What a gorgeous meter!  The sixth digit is very slightly brighter than the rest.  I ordered a new display.  Not so much because it's dim, rather to have a spare 10 years down the road.  Out of the box, it agrees closely with my Fluke 87V.  That's good enough for me; my repair and experimentation activities don't require extreme accuracy.

[DavidAzulay5000]

Testing 4 wire kevin sens cable thet I built
with my HP 34401A
with power resistor 10 milliohm
spot on

[nukie]

The first stop after I fixed all my used 34401A is the cal lab. Even just simple capacitor refresh. You never know what the equipment went through and they could have done repairs to the devices. Soldering can change alot of things especially with these precision equipment.

I have done some repairs to a few 34401A and I find even replacing the tantalum caps near the opamps pins can sometimes throw the calibration off the charts.

If you are certain that your equipment is good and want extra assurance you can always rent another 34401A from a reputable test equipment hire. They usually have yearly calibration done on them. If you are lucky it could be done recently. Then you can compare your equipment with the rented dmm.

[deepfryed]

I recently acquired one of these in good condition, but cost a fair bit more though - closer to A$650 

It does seem to agree with the precision resistor (0.005%, 0.2ppm/c) and reference (max6350 without trimming, 0.02%, 1ppm/c) I have (not calibrated), but as people have said can't be sure until it's calibrated. I'm not sure if it's purely coincidence or both the reference and resistor have the same error as the DMM 

The DMM cal menu says it was last calibrated in 1996, again don't know if people really update it.

I'd like to double check the "standards" I have if possible but don't want to spend another $200 on calibration / adjustment!  Is there a metrology group in Melbourne ?

[deepfryed]

I made myself a usbgpib adapter (https://github.com/xyphro/UsbGpib) and use the python-usbtmc library to read remotely. I can write something quickly to graph in realtime if necessary.

1000 readings/s is more than enough for my hobby needs.

[rhb]

The AR488 will take care of logging.  For hobby cal, join the USA cal club round 3.  I logged both my 34401As for several days in round 2 against the excellent voltage references that @TiN designed and built.

The  most heavily used  unit had been calibrated  about a dozen times.  The new looking unit had never been cal'd.  Extensive checks with limited kit showed them in spec for everything I could test.

Going price for a 34401A in NA is $325-$350.  3478A is $125.  That's both ebay and the test equipment lists on groups.io.  The 34401A may lack some convenience features, but the price-performance of the 34401A and 3478A can't be beat for reliability, accuracy and ease of repair or replacement.

Have Fun!
Reg

[Veteran68]

I have an Agilent 34401A (newer generation of the HP with black+red probe connectors) purchased from a member here on eevBlog for $250 just a few years back. Excellent condition and per my hobbyist references is still well within spec and plenty accurate for me. If I had a local cal lab I'd like to get it calibrated, but calibration will cost more than I paid for meter, especially if I have to ship it somewhere. I consider it probably my greatest bargain find in this hobby. While I do plan to pick up a Siglent SDM3065 to have the newer features, I will keep this one. It's fast, has a nostalgia factor and there's just something sexy about a VFD! Plus you know what they say: two is one, and one is none.

And do I *NEED* 6.5 digits for my hobby use? Not really, but I have a compulsion to get the best I can reasonably afford. I consider a good DMM to be the heart of any electronics bench and it's nice to know I have the extra precision should I ever need it. And I also have over a dozen handhelds ranging from higher end Fluke, Brymen, and Hioki to Uni-T, Aneng/Zotec, and Kaiweets (yes, I have a problem, I can't stop buying meters!). I've cut corners on a cheaper scope (not going to spend thousands for one when I seldom use it) and SigGen/AWG, but not my main DMM.