Options for a 5.5 digit bench DMM ?

[kcbrown]

If there is a fan in my 8251 it's either very quiet or not working, I have not opened mine (shame on me).

I might be mistaken.  On a 8251 teardown thread somewhere here on EEVBlog, there was a picture showing a circular opening on the left hand side which I assumed was for a fan.  Perhaps just passive ventilation instead then ?

I've opened mine.  It doesn't have a fan.

[usagi]

gdm-8251a is totally silent. no fan.

it's a fine bench dmm especially at $90.

[mtdoc]

None of my 3 bench DMMs have fans (GDM-8251a, HP3478a, Fluke 8842a).   

Do any bench DMMs have fans? They are low power devices.

[Geoff_S]

The Keysight 34461A that I've rented certainly does...

[EEVblog]

The Keysight 34461A that I've rented certainly does...

Yep, the biggies do.
Anything with a serious ovenised voltage reference will generally need one.

[HighVoltage]

The Keysight 34461A that I've rented certainly does...

Yep, the biggies do.
Anything with a serious ovenised voltage reference will generally need one.

The 34410A and 34411A also have a fan.
But if you reduce the fan speed by 50%, the noise level is so low that you can almost not hear it anymore and a slower fan speed has really no influence on the performance of the DMM.

[EEVblog]

Not 5.5 digit, but a nice price:
http://www.ebay.com.au/itm/Fluke-37-Multimeter-with-New-Battery-/361956632030

[mtdoc]

Yep, the biggies do.
Anything with a serious ovenised voltage reference will generally need one.

Good to know - and another reason why I shouldn't stray farther in the volt-nuttery direction.

Not 5.5 digit, but a nice price:
http://www.ebay.com.au/itm/Fluke-37-Multimeter-with-New-Battery-/361956632030

Whoa!  Good score for someone.

[usagi]

Not 5.5 digit, but a nice price:
http://www.ebay.com.au/itm/Fluke-37-Multimeter-with-New-Battery-/361956632030

i reckon its probably still within spec 

[EEVblog]

Not 5.5 digit, but a nice price:
http://www.ebay.com.au/itm/Fluke-37-Multimeter-with-New-Battery-/361956632030

i reckon its probably still within spec 

Practically guaranteed.
I like the fact that it has 1000hr battery life, but the form factor of a compact bench meter.
Nice meter to just have on the shelf for everyday measurements if you like the bench use scenario.

[EEVblog]

Yep, the biggies do.
Anything with a serious ovenised voltage reference will generally need one.

Good to know - and another reason why I shouldn't stray farther in the volt-nuttery direction.

Fan noise in a lab adds up. Can be bloody annoying.
Volt nuts need to leave stuff on 24/7 too.

[HighVoltage]

If you are looking vintage, there is a great old bench meter from Germany, made by Goertz Metrawatt BBC ABB
The MA5D
+/- 30.000 count
In the mid 80s it was made for research and development, lots of Universities had them in their labs
You can get them cheap sometimes on ebay Germany
The manuals including schematics are online.

[Geoff_S]

A bit confused...

My existing Fluke 87V handheld has a quoted accuracy of 0.05% and max resolution of 10 uV.  I can put it in mV mode (6 mV range), hi-res mode (20,000 count) and if I'm measuring a signal of few millivolts, it reads down to the nearest 0.01 mV.  I checked this against the 34461A and it was pretty spot on. 

But the Instek 8251 has a quoted accuracy of 0.012% and a minimum range of 100mV.  Does this mean it can also only read down to the nearest 0.012 mV (ie actually slightly worse than the 87V) ? 

[H.O]

The 8251A is 120000 count. On the 100mV range its full scale reading is 120mV and it's resolution is therefor 1uV. The specified accuracy on that range is 0.012% (of full scale I believe) + 8 digits. So any reading on that range should be within 0.012% of 120mV + 8uV = 22.4uV of the actual voltage. (Hope I didn't mess that up...)

EDIT: The FLUKE87V specifies its accuracy on the mV range as 0.1% of reading + 1 digit with a resolution of 100uV. Putting it in high res mode doesn't increase it's accuracy, just the resolution which becomes 10uV but now you have to add 10 digits of uncertainty to the 0.1%. So 120mV should be within 0.1%+100uV=220uV and 10mV should be within 110uV.

[tecman]

I have an HP 3457A and love it.  I do not think you will find a newer unit will be as robust as the older HP stuff.

paul

[bitseeker]

Currently I've narrowed things down to either:
- Agilent 34401A: around $350-400
- GW Instek GDM-8251A: around $100

Other than my immediate troubleshooting task, I don't think I'll really be needing the precision of the Agilent very often, and hence the Instek is tempting.  But I find it hard to go past the solid reputation of the Agilents.

Unless you need the dual-display of the Instek, I'd suggest getting the 34401A. Even if you don't usually need the full resolution, it'll be there when you do need it. Dive into the details to see if the other greater performance characteristics of the 34401A are worthwhile. Another thing to consider is that if something one day goes wrong with the HP, there's plenty of information and know-how available to repair it or have it repaired.

I've owned three 34401A meters. I currently have a 34401A and a 34410A. (No fan in the 34401A.)

[daveyk]

The 34401a is a excellent and the GPIB interface for VBA software control and data collection is really nice .


Sent from my iPhone using Tapatalk

[ebclr]

If price is a point to you consider this one

http://www.victor-multimeter.com/products/bench-type-multimeter/victor-8145b-dual-display-multimeter-638.html

[rsjsouza]

Just to stir the mix, I have two more suggestions that I personally have experience. If you are mostly interested in DCV and ohms (2 and 4 wire), the Keithley 191 is an excellent meter that can be had for a bargain (there's something about red LEDs that fascinate me). A bit more complete (full ACV, DCV, ACA, DCA and ohms) is a Racal Dana 5001 - these can be had for a bit more than the 191 but I am pleased with mine.

I just got a pair of 3478As on the cheap but I didn't have yet time to play with them. At first glance the 300000 counts is really a step up from the other two (200000 each) and their operation is very silent.

[usagi]

The 34401a is a excellent and the GPIB interface for VBA software control and data collection is really nice .

new ones will be spendy, used ones on ebay are a gamble. be prepared to fix them, as i had to with a recent ebay 34401a.

the ebay gdm-8251a tick every box for OP's requirement, are cheap, basically brand spanking new, and known to work. it's really a no brainer. lowball the seller and walk off with a $90 5 1/2 digit dmm.

[daveyk]

The 34401a is a excellent and the GPIB interface for VBA software control and data collection is really nice .

new ones will be spendy, used ones on ebay are a gamble. be prepared to fix them, as i had to with a recent ebay 34401a.

the ebay gdm-8251a tick every box for OP's requirement, are cheap, basically brand spanking new, and known to work. it's really a no brainer. lowball the seller and walk off with a $90 5 1/2 digit dmm.

Looks like a nice Agilent clone, but you are stuck with a Chinese meter. I don't know if you could find a lab to NIST certify that brand. If you are using it for work or equipment calibration, I'm sticking with Agilent/Keysite or Fluke.

It is strange to have that USB connector on the back. I don't have and flat USB to flat USB cables.

If I had $100 burning a hole in my pocket, I would order one for shits and grins.

Why would a used Agilent off of EBAY always need repaired if it has a 14 or 30 warranty/return policy?

Is it bad to buy any test equipment off of eBay?

In two weeks I am going to buy a Agilent 33250A, two scope GPIB interfaces, Agilent Attenuators, etc,.  Maybe I should get nothing from ebay?

I was going to have a cal lab cett the equipment as soon as I got it. If there a problem, back it would go. I see some sell it with a NIST cert. I emailed on and for about $100-$175 more, I could get the equipment with a new ISO 17025 accredited cert. If I do that, I would think I am somewhat protected against buying duds.

Now Yaa hot me worried. I wasn't going to buy the cheapest I could find. I was going to look for equipment dealers.

Dave

[HighVoltage]

Why would a used Agilent off of EBAY always need repaired if it has a 14 or 30 warranty/return policy?
Is it bad to buy any test equipment off of eBay?

I have bought lots of Agilent / Keysight and other brand gear of ebay.
Sometimes broken and it needed repair
And sometimes the seller claimed it was broken and in reality it was perfectly working - no repair needed.
And many times I have bought good working gear for unreal little money.

The smallest amount of money I paid for a good working 34401a was 150 Euro
And two 34410A (broken) for almost nothing and both got repaired perfectly.

It is always a risk but at least for me it was more than worthwhile.
I would always prefer an Agilent 34401A over a China clone.

[ebclr]

Chinese meter or Malaysia meter wasn't that difference

[bitseeker]

Chinese meter or Malaysia meter wasn't that difference

It's not the geographic region of manufacture that's the difference, although it often sounds that way. It's the brand and, hence, the likelihood of third-party (and sometimes even first-party) support. If you need to have a bench DMM serviced, which brands are more likely to be supported by a test equipment calibration and/or repair service? HP/Agilent/Keysight, Fluke, Keithley, etc. or Rigol, Siglent, Instek, etc.?

Not everyone necessarily needs that level of service. But, if you do, then that makes a difference.

If you repair your own equipment, availability of service information and parts are other factors. That's something where even brand doesn't necessarily make the difference. Often, it's the age of the equipment that makes or breaks DIY serviceability.

[usagi]

none of these requirements appear to be a concern of the OP.

it sure doesn't sound like OP is going to be running a cal lab. nor are calibration or absolute accuracy requirements of the OP.

just tested some microvolt readings. gw instek gdm-8251a, keithley 2015thd, agilent 34401a. 10uv would be pushing limits of the 8251a. 34401a readings are very unstable at this range. keithley 2015thd was very stable.