Looking for a bench multimeter

[unimorpheus]

I was originally considering the Rigol DM3000 series but the price for the 6.5 digit does not appear to be that competitive. I have been looking at Agilent, Keithley and Fluke and have been leaning toward Fluke only because I have/had 6 or so Fluke handhelds over the years. What I don't understand is the myriad of Agilent models both new and old. Can anyone provide some assistance on working out Agilent and Fluke bench DMM model numbering. I have been looking on eBay for some good used gear but I am not familiar enough with this gear to know good from bad. Not really sure if I really need 6.5 digits when 5.5 may be fine. Also what is the real dig against the Rigol meters? I currently have the DS2072a, DG4062 and DP832 that needs calibration hence the bench DMM. I don't think my Fluke 179 or twenty year old Fluke 87 series 1 is up to the task. Any advice would be welcome.

[nidlaX]

Here are some common Agilent / Fluke / Keithley multimeters to look for off the top of my head:

6.5 digit bench form factor:
Agilent 34401A
Agilent 34411A
Fluke / Tektronix DMM4040 / 4050
Keithley 196 (Vintage)
Keithley 2000 / 2015 / 2700

6.5 digit rack form factor:
HP 3455A (Vintage)
HP 3456A (Vintage)
HP 3457A (Vintage)
Keithley 193 (Vintage)
Keithley 2700 in a rack enclosure

5.5 digit bench form factor:
Agilent 34450A
Fluke / Tektronix DMM4020
Fluke 8800A / 8810A (Vintage)
Fluke 8860A (Vintage)
HP 3468A (Vintage)
Keithley 199 (Vintage)

If you get a meter that's described as used / untested, I would recommend searching the repair forum for potential issues that may be present.

[TheSteve]

You can also add the following Keysight  (Agilent) 6.5 digit meters:

34460A
34461A - more or less the sweet spot in the new line of meters that offers the most bang for the buck.
34465A


btw, I am not sure about a "dig" against Rigol meters but at the end of the day do you want a meter made by a chinese company that offers less support and has no history of top of the line commercial test equipment or do you want something made by Fluke/Keithley/Agilent/Keysight that have decades of proven performance?

[billfernandez]

You can also add the following Keysight  (Agilent) 6.5 digit meters:

34461A - more or less the sweet spot in the new line of meters that offers the most bang for the buck.

I recently bought this one.  I wanted a (to me) high precision, flexible, general-purpose bench meter.  I wanted to have confidence (yes confidence is an opinion, not an objective fact) that it would be reliable, long-lived, well-characterized (for when I really needed to get particular about measurement).  I wanted it to be a "modern" design with the implication that it would have modern features.  This one has Ethernet connectivity, built-in web server, BenchVue software for remote programming, compatibility with SCPI programming, and the ability to do things my old meters could never dream of, such as data-logging and graphical display of histograms, etc.

It's not the only meter on the market with these kinds of characteristics, but as TheSteve said, it's kind of a sweet spot in the contemporary bench meter market.

[nctnico]

I looked at Tektronix (Keithley) DMMs but I'm leaning towards the Keysight 34461A as well. The Tektronix DMM4040 looks just as accurate but it's input impedance is 1M Ohm where the 34461A has an input impedance of 10M Ohm with an optional >10G Ohm setting. I have run into several situations where a 10M Ohm input resistance is already too low. And let's not forget the color TFT display versus low resolutuion VFD.

But looking at the OP's requirement I doubt a 6.5 digit meter is required. Calibrating a scope, frequency generator and PSU should be perfectly doable with a 4.5 (5.5 at most) digit multimeter.

[KJDS]

I've got a pile of Solartron 7159plus 6.5 digit meters available. To be honest, they are more of a good 5.5 digit meter that displays and extra random number when asked than a true 6.5 digit meter, but they do make excellent bench meters when you do't need that last bit of resolution.

[HKJ]

The Tektronix DMM4040 looks just as accurate but it's input impedance is 1M Ohm

Where have you got that idea from? It has 10Mohm and >10Gohm settings.
I have two 8846A (The Fluke version) and they are very stable and precise, they basically matched my new Keithley DMM7510.

[nctnico]

The Tektronix DMM4040 looks just as accurate but it's input impedance is 1M Ohm

Where have you got that idea from? It has 10Mohm and >10Gohm settings.

You are right. I now see that was the AC specification table.

[Muxr]

It's a personal preference, but I actually like the VFD better. It just looks better than TFT with its backlight leak. Although TFT is superior in the amount of information it can display and longevity.

[generic_username]

I have a somewhat silly  question as I looked for a 6.5 Digit Meter myself in the past days.

If I buy a 6.5 Digit thing used it is certainly out of calibration and there's no way I'd have the equipment to cal such a meter myself(service manual of a Agilent 34411A states a Fluke 5720A )

So why should someone for hobbiest purpose getting a 6.5 digit meter ( although the used ones are fairly cheap)

[nctnico]

You can always choose to send a DMM in for calibration. No idea about the costs though but it must be less than a new DMM to make sense. Calibration costs will also depend on how difficult it is to calibrate the instrument.

[Muxr]

I have a somewhat silly  question as I looked for a 6.5 Digit Meter myself in the past days.

If I buy a 6.5 Digit thing used it is certainly out of calibration and there's no way I'd have the equipment to cal such a meter myself(service manual of a Agilent 34411A states a Fluke 5720A )

So why should someone for hobbiest purpose getting a 6.5 digit meter ( although the used ones are fairly cheap)

It's a risk you take when you buy second hand. I have a few voltage standards I use to check all my meters, like the DMM check plus, they aren't anything fancy, but it's good enough just to see if you're close enough, also ok for calibrating old 4.5 meters or oscilloscopes.

You also use your other meters to compare. Some folks may use a calibrated 6.5 (or higher res) meter they own and trust to be in spec to calibrate their other meters. There are also profesional voltage transfer standards you can calibrate and use to calibrate your other gear.

DMM check is useful as It basically just gives me a warm and fuzzy that the instrument is not horribly out of spec. I don't have a need for a 6.5 digit meter really, 5.5 is overkill for most stuff I do. The one I own I got it for the THD measurements (keithley 2015) the 6.5 resolution came as a bonus. My Fluke 87 Vs is what I measure voltages with most of the time, and it's good enough.

A meter may not be calibrated, but it can still provide good enough drift measurements if you're trying to measure drift in a circuit over a period of time with a higher degree of accuracy because 6.5 digit meters will have an oven controlled reference with little drift.

[HighVoltage]

I would vote for the 34401A if you want to save some money on a used meter.
There are plenty around and many times cheap.

Usually the 34401A stays very stable even years after the last calibration.
And if you don't need the last digit, most likely a used one will fulfill your need for accuracy.
In normal setting, when you turn on the 34401A it is in the 5 1/2 digit mode anyways, not even showing the last digit. I have bought many 34401 meters used on ebay and when they are not broken, they are usually within the Agilent 1 year specifications. Even more interesting, when I bought broken units and repaired them, many of them were afterwards within specifications as well.
 

[Fungus]

So why should someone for hobbiest purpose getting a 6.5 digit meter ( although the used ones are fairly cheap)

Bragging rights?

[TiN]

Bench DMMs are fun. Even if it's not calibrated but working properly, you still can benefit from 6.5 digits, using ratio measurements and comparing signals. Calibration is required only if you need to know absolute reading accuracy.

[Fungus]

Those things are designed not to drift.

Even if it hasn't been calibrated for ten years it's probably still OK for hobby use.

Calibration certificates are mostly for people who need to cover their asses in legal-liability situations.

Realistically, how often will you need make an absolute measurement to six digits? Not very often (maybe only for calibrating other instruments...)

If you want to watch changes in measurements then it doesn't have to be perfectly calibrated. I'd say this usage is more common for 6.5 digit meters than absolute measurements (eg. measuring ppm temperature coefficients, watching a battery draining...)

[saelig]

We have the Siglent 5 1/2 digit DMM SDM3055 on sale if that helps ....  We have two in stock now.  http://www.saelig.com/product/M00110009.htm

Alan Lowne
CEO Saeli Co. Inc.

[trevwhite]

I did get it cheap from Toploser but my Keithley 2110 performs really well. People noted the display was a bit flaky but it is actually only when first powered up that it's contrast appears a bit faded. After a few minutes the screen 'warms up' and is nice and clear. But even when first powered on the screen is fine. I used it just today with dual readings to monitor a battery being charged. I was able to monitor the voltage and current and log the readings together via the USB with the Keithley software. The software is not great but it has worked. I have a CSV file with all the data.

I think Keithley rebadged this meter from another company. Array? What I noticed was that Array sell it as a 6.5 digit meter whereas Keithley have chosen to sell it as a 5.5 digit. This makes me think Keithley did their homework on this meter and tested it properly before selling it on as if they just rebadged it they would have sold it as a 6.5 digit version? But I cant be sure of any of that.

Anyway, it has been a really good meter. One thing that I do struggle with and this might be because I am a bit deaf is I find the continuity beep quiet. I literally have to turn my ear towards the meter to know if its beeping or not. But I do struggle with high frequency so I can not tell if its the meter or me. Probably a bit of both.

I do not know what other data logging software is like but I would imagine Keysight would be hard to beat. My next bench meter will be a Keysight one but I am more than happy with the Keithley for now.

[ECEdesign]

I am also looking for an HP 34401A.  Local calibration lab will calibrate for 90 US dollar. Hopefully there will be a nice meter for a good price in May when I can purchase.  If not I guess ill go with the U1282A handheld by Keysight but for bench work I think I would prefer a benchtop meter.  The handheld is much more likely to get 'borrowed'

[ez24]

I would vote for the 34401A if you want to save some money on a used meter.
There are plenty around and many times cheap.

Looking at these on ebay, most if not all show a low DC voltage with no leads.  Such as 0.0xx mv

Using these, is there a way to zero this out, or do you need to subtract out this number?

This one shows  .052 mv

http://www.ebay.com/itm/Agilent-34401A-6-1-2-Digit-Multimeter-/172082055969?hash=item2810e3cb21:g:OpUAAOSwZG9WjH~H

[TheSteve]

The voltage displayed with no input is completely normal, it occurs because the meters have such a high input impedance. If you short the input they will likely read zero or very close to it.

[deadlylover]

Yep even with the 34401A in its default 10M input impedance mode, the display can show a few hundred counts with open inputs. They do have a math null function. 

The 34401A is fantastic value used, I know that one of my units has not been adjusted from factory since 1996 or so and it is still mostly within 1 year spec, it seems that the 10VDC range drifts 15-22ppm then slows drastically over the years.

[TheSteve]

If buying used the 34401A does seem like an excellent option, if buying new I'd aim for the 34461A. I know I quite like mine.

[ez24]

The voltage displayed with no input is completely normal, it occurs because the meters have such a high input impedance. If you short the input they will likely read zero or very close to it.

thanks

[HighVoltage]

http://www.ebay.com/itm/Agilent-34401A-6-1-2-Digit-Multimeter-/172082055969?hash=item2810e3cb21:g:OpUAAOSwZG9WjH~H

This meter looks in excellent condition.
Clean contacts in the front and rear terminals
Clean and no corrosion on the rear BNC
The display seems to be nice and bright
It is a newer model, Agilent branded and red / black terminals as to all red terminals in older HP models
It comes with handbooks
If you can get this for $ 350 or little above, it seems to be a real good deal

I would ask the seller if it passes the self-test procedure
Also, it does not come with the bumpers or handle, but those you can easily buy used or new on ebay.