Most Accurate Modern Handheld DMM? Just Curious

[Vgkid]

LT1236 ACN 8-10

http://www.linear.com/product/LT1236

http://cds.linear.com/docs/en/datasheet/lt1236.pdf

Thanks. Interesting that they are running a 10V reference in there. I'm wondering if those 2 beefy diodes in the pics are for a boost converter. Similar to one that is implemented in the datasheet(except that is for 5v reference running off a 5v supply).

The boost converter is max863, and you are right, the boost converter provide +5V for digital section, +8V for analog,  and there is a -8V come from +8V, don't known how to explain it in English.
attached a photo, that is what I learned when I repaired my 30M meter.

Your English explanation is good, there are no issues with it.
I guess they are using the +/-8v to create a floating 16v for the reference. That is a bit different, but oh well.

[Wytnucls]

Here is a 2003 model for sale in Germany. Has reached a fairly high price already, considering how old it is.

http://www.ebay.de/itm/Metra-Hit30M-Precision-AC-DC-/252754967403?hash=item3ad95ebb6b:g:Hw4AAOSwjDZYlc1M

[TheAmmoniacal]

Too bad neither of the listings offer international shipping! I would probably sacrifice both my U1272A and U1282A to get one of these!

[quarks]

USB TO IR  I used for data-log.....

Very interesting, so far I was not able to datalog my 30M.
Can you share some more details?

As others already stated the 30M is kind of unique and therefore is a great DMM, but there are some drawbacks I do not like.
- Battery runtime is only 15h to 16h!
- AFAIK there are no schematics available and also Gossen was not helpfull, when I contacted them and asked for calibration details. Even a cal lab I later contacted, said they do not get calibration details from Gossen.

It would be great if anyone could share how to calibrate a 30M.

[Assafl]

I can sort of rationalize why Gossen Metrawatt avoids giving out service and calibration guides for their low end products (planned obsolescence) .

But what is the use of making a 6 digit multimeter that cannot even be verified (unless you build your own test procedures)? I would highly expect T&M departments to discourage the acquisition of these (perhaps except for very specific niche mobile uses).

Bummer - The Gossen/Metrawatt/Camille Bauer 29s is my favorite handheld DMM (300,000 count, energy).

[Delta]

Do you mean most precise, or most accurate?

[Pipelie]

USB TO IR  I used for data-log.....

Very interesting, so far I was not able to datalog my 30M.
Can you share some more details?

As others already stated the 30M is kind of unique and therefore is a great DMM, but there are some drawbacks I do not like.
- Battery runtime is only 15h to 16h!
- AFAIK there are no schematics available and also Gossen was not helpfull, when I contacted them and asked for calibration details. Even a cal lab I later contacted, said they do not get calibration details from Gossen.

It would be great if anyone could share how to calibrate a 30M.

check out the link I posted(thanks to 0xdeadbeef who share the link with me), https://sigrok.org/wiki/Gossen_Metrawatt
look into the photos of Metrawatt BD232, you will find out it is just a simple, RAW RS232 ot IR adapter.
something like the "Fluke 189/187   USB-IR Cable adapter" will work on 30M for sure.
the adapter I use is a USB to UART,  part number of the chip is Pl2303, the circuit is quiet simple, you can tell by the photo.
or you can build  a RS-232 to IR adapter, schematic attached below , it will work properly. designed by Jambalaya.

[bck]

Hi,

attached is a lib for reading out the Metrahit 30M in python3

sample usage:

Code: [Select]

from lib.Metrahit30M import Metrahit30M
from time import sleep, time

a = Metrahit30M()
a.set_baudrate(9600)
a.set_device("/dev/ttyUSB0")
a.connect()

a.set_range(a.RANGES['VDC']['10V'])
while True:
    sleep(1)
    tmp = a.get_measurement()
    csv_data = str(time())+", "+tmp[0]+", "+tmp[1]+", "+tmp[2]
    with open("test.txt", "a") as file:
        file.write(csv_data+"\n")
    print(csv_data)


sample output:

Code: [Select]

1486926880.095561, +04.99996, V VDC, 10V VDC
1486926881.1968956, +04.99996, V VDC, 10V VDC
1486926882.2983227, +04.99996, V VDC, 10V VDC
1486926883.3987503, +04.99997, V VDC, 10V VDC
1486926884.5000813, +04.99997, V VDC, 10V VDC
1486926885.601423, +04.99997, V VDC, 10V VDC
1486926886.7028775, +04.99997, V VDC, 10V VDC
1486926887.8032846, +04.99996, V VDC, 10V VDC
1486926888.9046874, +04.99996, V VDC, 10V VDC
1486926890.0051658, +04.99996, V VDC, 10V VDC
1486926891.106339, +04.99996, V VDC, 10V VDC
1486926892.2070792, +04.99996, V VDC, 10V VDC

[bluey]

Presume the Gossen Metrawatt Metrahit 30M has been superceded by something newer. Eg Gossen Metrawatt Metrahit PM Prime +/- BT. Around 800 euros. 310,000 counts:

https://www.gossenmetrawatt.com/english/produkte/metrahit-pm-prime.htm

Maybe one of the Metrahit S series has higher spec?

https://www.gossenmetrawatt.com/english/produkte/metrahitsseries.htm

[EEVblog]

Presume the Gossen Metrawatt Metrahit 30M has been superceded by something newer. Eg Gossen Metrawatt Metrahit PM Prime +/- BT. Around 800 euros. 310,000 counts:
https://www.gossenmetrawatt.com/english/produkte/metrahit-pm-prime.htm

That's a replacement for the Ultra, not the 30M.

[rsjsouza]

This got me confused a bit as well. Earlier in this thread it was said the 30M had 200.000 counts, which put it on par with this modem and in the 5,5 digit multimeter range.

However, the 30M was indeed a 6,5 with its 1.200.000 counts.

[notfaded1]

WIKI with internal pictures:  https://sigrok.org/wiki/Gossen-Metrawatt_METRAHIT_30M

[joeqsmith]

Presume the Gossen Metrawatt Metrahit 30M has been superceded by something newer. Eg Gossen Metrawatt Metrahit PM Prime +/- BT. Around 800 euros. 310,000 counts:

https://www.gossenmetrawatt.com/english/produkte/metrahit-pm-prime.htm

Maybe one of the Metrahit S series has higher spec?

https://www.gossenmetrawatt.com/english/produkte/metrahitsseries.htm

 
So they obsolete the Ultra and replace it with the Prime.  They don't clearly state in their literature what makes the Prime different from the Ultra.   Then the best part, they use the exact same M248B part number for both meters.   

Someone had wrote me a while back that Gossen had told them they had added a shield to the Ultra, actually calling out the Netic material I had used.   Maybe the Prime addresses some of my concerns with the Ultra.   I will write them. 

[joeqsmith]

Sadly but not too surprising, no response.   I used the same email address and history chain and wasn't trying to hide the fact that I had looked at the Ultra.   Rather than to look at it as an opportunity to show off the Prime, it seems they have little to say about it.   

Again, if they addressed the problems with the Ultra, I would be willing to have another look at it.   I can't see buying the Prime just to find out that their marketing group felt giving it a new name was going to solve the problems.       

[rsjsouza]

It is indeed sad. Their silence comes across as very arrogant, especially if the product revision was partially based on your conclusions (this is unconfirmed, right?). Oh well... We can't always win.

[niner_007]

Easy, Gossen Metrahit 30M
World's only 6.5 digit handheld
https://www.gossenmetrawatt.com/english/produkte/metrahit30m.htm

6.5 is the resolution not accuracy, if I'm reading their accuracy spec right, basic DCV is 34ppm, and the time range is not specified, I assume per year

(I edited my post as a I was wrong) this is actually pretty good, but stability and noise figures are not specified

you should look for a bench DMM if you need accuracy and solid specs expected from a 6.5 meter, the Gossen is already in that price range, with worse specs

[joeqsmith]

It is indeed sad. Their silence comes across as very arrogant, especially if the product revision was partially based on your conclusions (this is unconfirmed, right?). Oh well... We can't always win.

I can't personally vouch for them having made any changes outside of the new name.   

You could also try contacting them.  They may be more open to having a dialog with someone besides me.  If you do try, I would be interested in hearing what becomes of it. 

[bluey]

It is indeed sad. Their silence comes across as very arrogant, especially if the product revision was partially based on your conclusions (this is unconfirmed, right?). Oh well... We can't always win.

I had no problem getting Gossen to answer my question about TRMS in the cheap models.

vertrieb@gossenmetrawatt.com