A tale of two meters

[joeqsmith]

Well, you hopefully won't get the glass fuses like you saw with your last crap meter.  Then these should actually pass the EMC standards, which while I never tested the UNI-T you had, I would bet it would fail on that grill starter test.  Having it certified is a big deal.  For $100, my expectations are pretty low. 

What would the Extech branded one cost?  Where I bought mine from, it was $300. 

http://www.testequipmentdepot.com/extech/multimeters/industrial-true-rms-digital-multimeters/true-rms-industrial-multimeter-datalogger-1000v-20a-wireless-pc-interface-ex540.htm

[3nigm4]

What would the Extech branded one cost?

The rebranded EX542, cost 302€... twice the CEM price
http://www.tme.eu/it/details/ex542/multimetri-digitali-portatili/extech/

[joeqsmith]

Mine made it in.  Branded CEM, blue TUV and GS cert.  I thought it may not be use 915MHz but it appears the software is the same between the two meters.   Both meters work with both adapters.    I never tried it until now but the software handle two meters logging to it at the same time.   

A $300 meter for $100.  At a glance, it looks legit.  So what gives? 

I was going to run an analog meter next but I am really curious about this thing.   Let me know what you end up with. 

[3nigm4]

Mine is currently waiting at the local courier depot 'cause yesterday was an holyday... I don't think to wait until monday... if this morning they are open I'll go picking it 

Edit: I abandoned the idea... it's an odyssey tring to contact DHL (toll number) to know if the local office is open

[joeqsmith]

No problem.  I spent the day working on a review for it.   I keep thinking this meter cost less than the Hioki DT4252, the Fluke 115 and the EEVBLOG rebranded Brymen BM235 with much higher performance and it was independently certified.  Of course, it may fail the grill starter test like so many UNI-Ts....   

I still need to run the continuity test, pull the thing apart and run the HV test on it before starting the destructive tests.   I may hold  off the destructive tests until you receive yours.  If you end up with a problem, at least we could compare results.   

[evava]

Joe, would you be so kind and try overloading this meter with AC volts on DC range, and with DC volts on AC range, like in this thread?
https://www.eevblog.com/forum/testgear/brymen-multimeters-fault/75/

And please, continuity is? (very slow, slow, fast, very fast ?)

Thank you.

[3nigm4]

...it may fail the grill starter test like so many UNI-Ts....   

I hope for a better result... but the grill starter... is the grill starter

I still need to run the continuity test, pull the thing apart and run the HV test on it before starting the destructive tests.   I may hold  off the destructive tests until you receive yours.  If you end up with a problem, at least we could compare results.

Tomorrow I'll get it and give it a try... in the meantime, don't be too harsh with it, poor baby

[joeqsmith]

Joe, would you be so kind and try overloading this meter with AC volts on DC range, and with DC volts on AC range, like in this thread?
https://www.eevblog.com/forum/testgear/brymen-multimeters-fault/75/

And please, continuity is? (very slow, slow, fast, very fast ?)

Thank you.

Good idea.  No problem, I'll add it to that thread.   

I have ran my normal continuity test and have updated the spreadsheet with that data.   

https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat

[joeqsmith]

...it may fail the grill starter test like so many UNI-Ts....   

I hope for a better result... but the grill starter... is the grill starter

I still need to run the continuity test, pull the thing apart and run the HV test on it before starting the destructive tests.   I may hold  off the destructive tests until you receive yours.  If you end up with a problem, at least we could compare results.

Tomorrow I'll get it and give it a try... in the meantime, don't be too harsh with it, poor baby

I finished up the HV tests last night.  I just need to pull it apart and see what's inside.   I'll run the transient tests no matter what I find.

Rather than a 2 part where I show the transients separate, I may just wait and put it all in one video.  So depending how your meter works out, I may not post the video for another week.  Personally, I am really curious how this thing stacks up.  At $120 it could end up being a great deal (until I find the glass fuses inside  )!   

[3nigm4]

Tested various functions, seems to be ok, even the PC connection... let's go with the grill starter 

[joeqsmith]

    Looks like you have the same meter.  Post the first 4 or 5 digits of the SN#.  Did you check your RF link too?

[3nigm4]

A few pictures 

The serial number starts with 141200...

Mine has also the floating/raising value while repeatedly turning light on/off; but is not a backlight issue: in my case it's related to buzzer... if I turn off the beep in settings, the value stays stable.
And yes, the RF module works fine

[3nigm4]

And one fix: the shield was bent and not soldered in one side.
Added also a bit of tubes on resistors.

[joeqsmith]

The serial number starts with 141200...

Mine is 130519... Sounds like if you are putting heat shrink over parts and correcting the soldering, you're keeping it.  For the price, it's a pretty good meter. 

I'll warm up the grill starter... Can it beat the Fluke 87V?   I have low expectations....    



 

[3nigm4]

The  RMS converter is an AD636 marked CJ
The case is marked 11/14 so it is built november 2014 and seems that the serial number match that period

Edit: there is no shielding on the back case

Edit2:

Is there any rework under the large fuse?

If you look at picture picture 7, there is a normal resistor in place af an SMD version soldered in on the near component

[3nigm4]

First picture, under the fuse; second picture, added back shield with a free zone around the RF antenna

[3nigm4]

Watched your video and it seems that the meter defends well
For the backlight on/off AC issue, as I said previously, try to disable beep in setup: in my case it stopped raising the AC voltage

[joeqsmith]

For $120, hard to knock it.  Was glad I finally was able to run one. 

I turned off both the Extech and CEM's phonating function.   I then left the meters on for 1 minute.  I then pressed the pressed the crap out of the BL buttons.  Both meters did the same thing, no effect.   So yes, it appears the problem is tied to the beeper.   

With yours having a CJ part and higher SN, I suspect it will run to a lower voltage.  I did not check mine but that new Extech will run the battery into the ground before it stops working.   

[3nigm4]

With yours having a CJ part and higher SN, I suspect it will run to a lower voltage.  I did not check mine but that new Extech will run the battery into the ground before it stops working.

I'll give it a try in next days

[joeqsmith]

I thought the one thing that would have gotten your attention was the 150MHz frequency counter. 

My CEM will turn on the Low Battery at 6.98 volts but will run down to about 4.6 volts.   Current draw @ 9 volts is about 4.8mA.  With back light and RF about 36 mA peak (when sending data). 

[3nigm4]

I thought the one thing that would have gotten your attention was the 150MHz frequency counter. 

Yep! Enough for my needs at the moment
Thank you for the video and for all the testing... and to reveal its physical limits

[SeanB]

Just how much voltage were you putting in to get it to 150MHz, useful, but carrying around a power amplifier for that might limit the usefulness of it at the high end.

[joeqsmith]

Just how much voltage were you putting in to get it to 150MHz, useful, but carrying around a power amplifier for that might limit the usefulness of it at the high end.

I really had no idea.  I was not trying to nuke the meter and the load was cold throughout the testing.  The amplifier was idling.   But, because you asked and it may actually be of interest to others, I ran the CEM at 154MHz, then adjusted the amplitude just to where it could read it.  I used an active probe to take this measurement, so the numbers on the LeCroy are not scaled as they would be with the monitor port on my load.  So roughly 3.2V.   

I can drive it direct with the signal generator in overload.  Now if using a meter is this way is useful to someone, I can't answer that.  Personally, I would use a counter. 

[3nigm4]

That's good. For accurate frequency check I too prefer a frequency counter, but in my actual needs, I use this to check the average throughput of my embedded appliance and see if I can optimize it or not. That frequency is TTL 3.3 V so it's level is high enough, and hardly go beyond 40MHz: the clock is 85MHz and the maximum managed bit flip I can do in code will be near half of the MCU clock.

[3nigm4]

My CEM will turn on the Low Battery at 6.98 volts but will run down to about 4.6 volts.   Current draw @ 9 volts is about 4.8mA.  With back light and RF about 36 mA peak (when sending data).

I tested only the voltage and the low battery appear at about 7V... at 4.7V the display starts dimming and at 4.5V is no more readable... the value read is stable even while dimming out