Yet another DMM request... pfffff...

[3nigm4]

Ok, I'm just looking averywhere on the web and here to try to find a goot DMM for my needs
I've already watched all Dave's and other members videos and now it's the time to ask if I am missing something

The most use I do of a multimeter if for low voltage applications... usually I repair whats broke up in my life: notebooks, smartphones, motherboards, audio/video equipment, etc... other times I build something I have in my mind
Sometime I need to repair switching PSUs and those times I reach my maximum voltage: about 400V rectified (those times I use an oscilloscope)

My actual equipment used in the last 20 years:
- a cheap "FUKE" chinese DMM, 1999 counts, manual range, bought in an electronic trade fair
- another cheap unbranded chinese rugged DMM, 1999 counts, manual range... I don't know why and when I bught it 
- another small repaired DMM, found broken somewhere
- an old Philips dual track 50MHz oscilloscope

Both multimeters has only one standard 250V glass fuse, and I've never broken one.

Lately I started to build some embedded applications with Arduino and similar HW, and developing the firmware I found the need for an upgrade of my equipment... the last one is about 25 years old 

So, what miss and I'm looking for needs to have:
- price under 200 €
- not less than 100 MHz logical frequency counter
- duty cycle
- PC connection (USB or BT)
- a good precision if preferred
- temperature is also preferred
- input protection is NOT needed... with both chinese cheap crap (and after inadvertently touching main) I'm still alive 
EDIT: - AA or AAA batteries are preferred but an utopia

First option is to buy 2 DMM with different target:
- general use: UT139C (Tenma 72-7780)
- digital/log up to 220 MHz: UT61E (Tenma 72-10415, Gwinstek GDM-461) / Victor 86E / Owon B41T

Second option, an all-in-one a bit more expensive:
- up to 200 MHz: UT71B (Tenma 72-7730A)
- up to 400 MHz: UT71C (Voltcraft VC920) / UT71D (Tenma 72-7732A, Voltcraft VC960) / Voltcraft VC880
- up to 100 MHz: Extech Ex542 (CEM DT-9930)

The specified frequency ranges are real or only on paper? I've not found nobody testing more than 40 MHz

I've looked also to known better brands (such Brymen BM829s) but are limited to 1 or 2 MHz

Thank you in advance for your precious help and for this great blog 

Moreno

[rsjsouza]

The UT139 and UT61 are very well accepted by a number of forum members, therefore this, tied to the fact that two DMMs are a big helper in several scenarios, makes me believe the first option is the best.

That said, I personally find very difficult to believe these meters can reach such high frequencies without significant losses. After all, connecting the long probe wires to circuits operating above several MHz will certainly act as very efficient antennas!

[3nigm4]

Thanks for reply

The fact is that both UT139C + UT61E cost me about the same as a UT71D... and I don't know if the more functions of the last will come handy in the near future

That said, I personally find very difficult to believe these meters can reach such high frequencies without significant losses. After all, connecting the long probe wires to circuits operating above several MHz will certainly act as very efficient antennas!

Yes, you are true... I think to use the oscilloscope probe with the bnc->banana adapter to avoid that... ummm.... 

[3nigm4]

Bought an UT71D on Amazon.it for 128 € including shipping
Hope to done the right thing for my needs... I'll report some picture

 

[SingedFingers]

Just a heads up with the frequency counters in DMMs, at least with experience from the UT61E. They're pretty good and will hang on to about 70-80MHz fine but the resolution is low to the point it's useless for more than a few MHz (22,000 count on the UT61E), the circuit impedance is terribly variable over the entire range, they inject noise galore into the DUT and as for the amount of RF that the device chucks out if you put some power down it is anyone's guess. The killer for me though is that you can't see frequency drift easily unless you have more digits. 28.014MHz which is what the display shows is missing an entire KHz worth of resolution. Could be 10-50Hz/minute drift easily.

[rsjsouza]

Bought an UT71D on Amazon.it for 128 € including shipping
Hope to done the right thing for my needs... I'll report some picture

 

Congratulations with your purchase! I hope you enjoy it and please post some pictures - we all love to see new gear.

I just recalled that Dave reviewed and did a teardown of the UT71E and IMO he was expecting more than he should have. But there are some folks reporting they have been consistently improving their meters. If you are interested, take a look at:
https://www.eevblog.com/forum/blog/eevblog-712-uni-t-ut71e-multimeter-%28why-uni-t-meters-suck%29/

[3nigm4]

The killer for me though is that you can't see frequency drift easily unless you have more digits. 28.014MHz which is what the display shows is missing an entire KHz worth of resolution. Could be 10-50Hz/minute drift easily.

Yes, that's right, but for my needs it's just enough: I need to see the rate of my little embedded projects that are below 100 MHz, just to see if my code is optimized or I need to change something... the measurement must give me an idea, not the exact Hz
In the future if needed, I'll look for a bench frequency meter 

Congratulations with your purchase! I hope you enjoy it and please post some pictures - we all love to see new gear.

Thank you ... I love that too... I looked all teardowns of the web till today

I just recalled that Dave reviewed and did a teardown of the UT71E and IMO he was expecting more than he should have. But there are some folks reporting they have been consistently improving their meters. If you are interested, take a look at:
https://www.eevblog.com/forum/blog/eevblog-712-uni-t-ut71e-multimeter-%28why-uni-t-meters-suck%29/

Yep! I know by heart all Dave's exclamations and laughter
For my usage I think it to be the best compromise