A tale of two meters

[joeqsmith]

I personally like the 181A.  The things you may want to consider are that the LCD lens is easily scratched. You can't use the meter while it is charging and I am not aware of them offering a spare battery.  They claim 40 hours of run time and the two times I have charged it, it sat overnight.   The charger does not come with any AC plug adapters.  Not certified to meet the EMC standards, or the safety standards for that matter.  While the meter may very well be "safe" it is not very robust and easily damaged (like most UNI-T meters  I have looked at).  If you watched the video how I attempted to harden the UT61E, I had a couple of cuts in the PCB to add a few parts.  Improving the UT181A was not so simple.  It really needs a new rev of the circuit board. 

On the plus side, it basically drives like a Fluke 289.  They actually used some decent parts, at least in the one I have.  It is the most temperature stable meter I have looked at.   I have not owned it long enough to say anything about the long term drift but so far it seems to be well within calibration.   Of the meters in that video, I still would hands down take the Brymen BM869s. 

[3nigm4]

What I don't like about brymen is the limited frequency counter.... only 1 MHz
I also found good for me the Amprobe AM570 in the same price segment, with less features than brumen but 60 MHz and no PC connection
I'll continue my research
Thank you for your videos, i watched about all    very informative 

[3nigm4]

How do you compare the EX540 to U71x series? I see that both share the same controller, the ES51966. Th main difference is the MCU, where di Extech/CEM use the Atmel ATMEGA32 and UT71x the TI MSP430.
I feel like the Extech is best designed but with cheaper components.
If you have to choose between them, witch one you will pick?

[joeqsmith]

I have never looked at any of the UNI-T UT71's so I have no way to compare them beyond what is in the manuals.   Typically I see glass fuses inside only the poorest of the meters and was surprised to see them.   

It's pretty rare I need to measure frequency with a handheld for the reasons I mentioned earlier. You are correct that the manual for the BM869s shows for logic levels, the frequency range is 5Hz to 1MHz.   In the AC line they list a maximum of 200KHz.  And I am sure that they all meet this standard.  However, consider the attached two pictures. 

While I am not a fan of the UT61E, I think it was able to read the highest frequencies of all the meters I have looked at so far.  They are not a lot of money here.   Personally, the lack of a backlight and the fact that I could damage it so easily, I would have no need for one.   They do come with the cable to log data.  Some charge extra for this.   

After watching some of my videos, you know I typically run them to failure using a common test.   The EX540 I have (even thought it's new) has been changed so much it would not be a good indicator of how a stock one would perform against the other meters.   

If I had to choose I would take my older 540.  The quality of the new one really suffered.       

[joeqsmith]

You may have noticed my scribble marks on the amplifier was 400KHz to 14MHz.   

[joeqsmith]

The scope, like the meters is not real good for a counter.  The first picture is with my old HP RF generator which I am using to drive the amplifiers.   The second picture was using my Marconi generator without an amplifier terminated to my old HP counter.  Both RF generators and the counters are referenced to a GPS that runs 24/7.   I was actually surprised that the Brymen was this tight. 

While I did damage this meter during my transient testing, I did not change anything in the design during my repairs.  I would expect another BM869s would behave much the same but we are running it way outside of their specs so you never know. 

[joeqsmith]

And just so you have some sort of accuracy data to go with it.  I have never attempted to adjust the clock reference for any of these meters. 

[3nigm4]

Thank you joeqsmith for all

I did not think were possible to reach such frequencies with that meter. From the cheap seller I can take it for about 240€ shipped without USB cable... I'll take a bit of time to think 

[joeqsmith]

No problem.  Glad to help.

Most of my test equipment I bought used.  This is one of the Fluke 97 scopemeters I found locally. They were a little rough from a garage life but working for the most part.   The meter function reads to about 5MHz on this one and the scope you can see is much worse. 

I would guess you could get a good counter for little money and then focus on some of the more important functions you may want the meter for.   

[3nigm4]

I am also thinking to buy a Brymen and build a prescaler for fast TTL frequency check.

Another question about EX540: I see that it uses an AD636 but from your pictures I'm not able to see if it has also a voltage reference IC somewhere

[joeqsmith]

If you watched that video I made where I attempted to improve the temperature drift of the UR61E, you will notice that the EX540 had the worst drift of the meters I have tested.   I'm sure they use a reference, but I have never had a reason to dig into what they used.  The AD636 is some knockoff part.

[3nigm4]

The AD636 is some knockoff part.

Yes, the True RMS converter.

I'm keeping to thing about it 'cause lately the prices here in EU is raising fast... maybe due to the USD running close to EUR (today 1€ = 1.058$... while a year ago ~1.20$ and 10 years ago ~1.60$).. at the moment:

- Uni Trend UT181A (60MHz, USB adapter included, ES51997+Cortex 32bit+TFT): 270~350€
- Brymen BM869s (1MHz): 219€ (259€ with USB adapter)
- Uni Trend UT71D (400MHz, USB adapter included, ES51966+MSP430): 173€ (130€ non GS/TÜV approved)
- Brymen BM867s (1MHz, no temperature): 159€ (219€ with USB adapter)
- Amprobe AM-550 (60MHz, 6000 count, no PC connection): 158€
- CEM DT 9939 (100MHz, USB adapter included, slow display, ES51966+ATMEGA32): 155€
- Brymen BM829s (1MHz): 150€ (190€ with USB adapter)
- Uni Trend UT71C (400MHz, USB adapter included, ES51966+MSP430): 148€
- Uni Trend UT61E (220MHz, USB adapter included, no temperature, ES51922): 87€
- Uni Trend UT139C (10MHz, no PC connection, DTM0660): 40€

[joeqsmith]

I had swapped out the 636 on mine to see if it was the cause of one of the problems.   It wasn't.  Lost interest in it.  You spend over $100 on a meter, you would think it would work right out of the box and it would be as good or better than the exact same model purchased a few years prior.   There are some odd ball brands of this same meter on Amazon for 1/3 the price of the rebranded Extech.  That would be a fair price but I wonder if they cheapen it up even further. 

[.rpv]

The AD636 is some knockoff part.

Yes, the True RMS converter.

I'm keeping to thing about it 'cause lately the prices here in EU is raising fast... maybe due to the USD running close to EUR (today 1€ = 1.058$... while a year ago ~1.20$ and 10 years ago ~1.60$).. at the moment:

- Uni Trend UT181A (60MHz, USB adapter included, ES51997+Cortex 32bit+TFT): 270~350€
- Brymen BM869s (1MHz): 219€ (259€ with USB adapter)
- Uni Trend UT71D (400MHz, USB adapter included, ES51966+MSP430): 173€ (130€ non GS/TÜV approved)
- Brymen BM867s (1MHz, no temperature): 159€ (219€ with USB adapter)
- Amprobe AM-550 (60MHz, 6000 count, no PC connection): 158€
- CEM DT 9939 (100MHz, USB adapter included, slow display, ES51966+ATMEGA32): 155€
- Brymen BM829s (1MHz): 150€ (190€ with USB adapter)
- Uni Trend UT71C (400MHz, USB adapter included, ES51966+MSP430): 148€
- Uni Trend UT61E (220MHz, USB adapter included, no temperature, ES51922): 87€
- Uni Trend UT139C (10MHz, no PC connection, DTM0660): 40€

the 61e includes a RS232 adapter, not usb, I tried with a RS232 to usb adapter and didn't work.

[3nigm4]

the 61e includes a RS232 adapter, not usb, I tried with a RS232 to usb adapter and didn't work.

Not the EU version sold by some german seller. The whole UT61x series there is sold with USB cable

[.rpv]

the 61e includes a RS232 adapter, not usb, I tried with a RS232 to usb adapter and didn't work.

Not the EU version sold by some german seller. The whole UT61x series there is sold with USB cable

Oh!, I didn't knew, that's a very nice add, RS232 is just 

[3nigm4]

Oh!, I didn't knew, that's a very nice add, RS232 is just 

Yep! That's absurd in 2016.. ops, 2017 that something is sold with a so old connection

[3nigm4]

I ordered on of the dirt cheap CEMs.   I'll do some sort of tear down and compare it with the Extech. It's almost a 1/3 the price so I am expecting they really cut out some corners.  If it looks the same as the Extech and there is nothing major wrong with it, I'll go ahead and run it.

I couldn't wait and ordered one me too 
I'm excited to see your job 

[IanB]

the 61e includes a RS232 adapter, not usb, I tried with a RS232 to usb adapter and didn't work.

Not the EU version sold by some german seller. The whole UT61x series there is sold with USB cable

Oh!, I didn't knew, that's a very nice add, RS232 is just 

Do meters with a USB connection create a virtual serial port on the host computer? For me the advantage of RS232 is that I can directly access the meter comms and write my own logging software. If there is no comm port to access this becomes much more difficult.

[joeqsmith]

Do meters with a USB connection create a virtual serial port on the host computer?

 

All the ones I have looked at do, including this meter.

I ordered on of the dirt cheap CEMs.   I'll do some sort of tear down and compare it with the Extech. It's almost a 1/3 the price so I am expecting they really cut out some corners.  If it looks the same as the Extech and there is nothing major wrong with it, I'll go ahead and run it.

I couldn't wait and ordered one me too 
I'm excited to see your job 

 

I never heard of the place I ordered mine from.   Even their ad shows the meter with two different colors.  One CEM blue, the other Fluke yellow.   They do not say if they use the 400 or 900 MHz radio.   It's a total grab bag!  But it's so cheap, we just have to have a look.  It will be funny if this meter actually turns out good.  They show it meeting the standards so they shouldn't have pulled the HRC fuses and replaced them with glass.    40,000 count, tri-display, AC-DC and an RF link for $100, what could go wrong!?    Post pictures of yours when you get it.  This is a link to the ad of the one I have on order.

http://www.ebay.com/itm/DT-9939-Waterproof-Industrial-Wireless-USB-RMS-Multimeter-Capacitance-Frequency/132045551020?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3Df8991ab2c3064b60bcbce643365f4625%26pid%3D100338%26rk%3D1%26rkt%3D4%26sd%3D181215338698

[ProBang2]

I hope you get the blue one (but I doubt). It is authorized for the european market.
Impressive: It is still rated as Cat IV 600V / Cat III 1000V (different to the downrated UT61E).

And there is the Certificate...

[3nigm4]

...Post pictures of yours when you get it...

Of course I'll post them 

In the meantime, this is mine https://www.reichelt.de/Digital-Multimeters/CEM-DT-9939/3/index.html?ACTION=3&LA=446&ARTICLE=134762&GROUPID=4058&artnr=CEM+DT-9939&SEARCH=dt9939

[3nigm4]

I never heard of the place I ordered mine from.   Even their ad shows the meter with two different colors.  One CEM blue, the other Fluke yellow.   They do not say if they use the 400 or 900 MHz radio.

I prefer the Yellow one, but it seams only sold in USA (the one you bought) or the one rebranded Jaycar QM1575
Your should be the 915 MHz (USA version), that is like the EX540

It's a total grab bag!  But it's so cheap, we just have to have a look.  It will be funny if this meter actually turns out good.  They show it meeting the standards so they shouldn't have pulled the HRC fuses and replaced them with glass.    40,000 count, tri-display, AC-DC and an RF link for $100, what could go wrong!?

I'm confident, we just have to wait

Edit: this is a picture from mjlorton forum http://www.mjlorton.com/forum/index.php?action=dlattach;topic=191.0;attach=3016;image

[joeqsmith]

Looks like it has been shipped and due to arrive this week.  It looks like the blue one you linked costs more than the one I have coming.  It will be interesting to see if yours and mine have the same problems my last EX540 has.  If the new meter works, I may have to take some time and really dig into what is going on with the 540.   

[3nigm4]

It looks like the blue one you linked costs more than the one I have coming.

Yes, and is the lowest price I've found here... even the one you bought, imported here with taxes and duties will cost me about 200€