MJLorton Solar Power and Electronic Measurement Equipment Forum
Product Reviews => Product Reviews => Topic started by: iloveelectronics on October 13, 2012, 12:13:26 AM
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Hello all and hi Martin, Franky here :) I just got myself a UT61E and I must say that I'm really pleased with it thus far!
Despite it being VERY cheap, it is very fast, both in terms of auto ranging (it's lightning fast!!) and its continuity test. Screen update rate is reasonable (about 3 times a second I reckon). It has decent build quality inside and out, obviously not Fluke quality when it comes to input protection and so on but at <20% of the price I wouldn't expect that.
The DCV accuracy was slightly out of spec when I first got it (about 0.15-0.18% low consistently) but after fooling around with some trim pots it's almost spot on now, based on my only references of the DMMCheck Plus and the PentaREF anyway. I have no clue how to adjust the resistance readings as I'm very much a noob but they are within specs out of the box. Can't tell how long it's going to stay accurate though with a cheap meter like this.
It also comes with the software and RS232 cable to connect to the PC. I haven't got a Rs232 to USB converter yet so haven't tested that, but I don't expect any drama there.
Overall for its price I believe it's very hard to find competition!
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Tinkering and calibration adjustment just few minutes out of the box ?
Franky all those manufacturers have serious equipment as calibration standards,
personally I think that you did a major mistake about tweaking a fresh meter with those devices which are made for hobbyists.
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Tinkering and calibration adjustment just few minutes out of the box ?
Franky all those manufacturers have serious equipment as calibration standards,
personally I think that you did a major mistake about tweaking a fresh meter with those devices which are made for hobbyists.
You're probably right...LOL! As I mentioned, I'm a newbie and half the time I don't know what I'm really doing :p In any case, it just makes me feel better seeing the readings get closer to what I expect. The meter is so cheap (less than $40 shipped for me) I'm willing to risk messing it all up. I don't really need another meter to be honest, it's another one of those "multimeter addiction" syndrome things! I still have a Brymen 867 to go to in case I want a bit more accuracy and confidence.
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In my youth I also took apart one Police car (toy) so to find about their internals,
the problem is that at the age of seven, you are unable to reassembly it. LOL
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Hello all and hi Martin, Franky here :) I just got myself a UT61E and I must say that I'm really pleased with it thus far!
Despite it being VERY cheap, it is very fast, both in terms of auto ranging (it's lightning fast!!) and its continuity test. Screen update rate is reasonable (about 3 times a second I reckon). It has decent build quality inside and out, obviously not Fluke quality when it comes to input protection and so on but at <20% of the price I wouldn't expect that.
The DCV accuracy was slightly out of spec when I first got it (about 0.15-0.18% low consistently) but after fooling around with some trim pots it's almost spot on now, based on my only references of the DMMCheck Plus and the PentaREF anyway. I have no clue how to adjust the resistance readings as I'm very much a noob but they are within specs out of the box. Can't tell how long it's going to stay accurate though with a cheap meter like this.
It also comes with the software and RS232 cable to connect to the PC. I haven't got a Rs232 to USB converter yet so haven't tested that, but I don't expect any drama there.
Overall for its price I believe it's very hard to find competition!
Hello Franky!
Hats off to you for getting it....and for Tinkering!!!! I love it!
Now then, someone else warned my about accuracy issues on the UT61E so this is something I will take a close look at that.
Chat soon,
Martin.
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The DCV accuracy was slightly out of spec when I first got it (about 0.15-0.18% low consistently) but after fooling around with some trim pots it's almost spot on now, based on my only references of the DMMCheck Plus and the PentaREF anyway. I have no clue how to adjust the resistance readings as I'm very much a noob but they are within specs out of the box. Can't tell how long it's going to stay accurate though with a cheap meter like this.
I can't honestly see them on the production-lines messing around trying to really fine-tune these; so long as they are within spec, they probably just pack them in the box. So you might well be able to squeeze a little bit more out in some cases. It's always good to have 2 meters just to cross-check though.
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I think I'm the one Martin referred to about warning of UT61E accuracy issues. I have a UT61E here that I purchased early 2012. The first thing I noticed after opening the box was that it drifts quite a bit on DCV, and resistance is on the low side. For example, my 5V reference (stability verified with better equipment) may read 4.993V now and 5.002V later. Most of the time but not always, the excursions are within its specified accuracy. The most annoying thing is that this drift seems to be accentuated by using other functions. Example, take a DCV reading, then measure a resistance or a capacitor, then go back and take the same DCV reading, and it will be several counts different. It usually drifts back to the original reading within a minute or so.
I have thought about 'tweaking' the DCV calibration pot, but it would be difficult get actual improvement. The best result I could hope for is to try to center the excursions symmetrically around the actual reference value. Too much trouble for too little gain.
Given this behaviour, and considering that everything except DCV is specified at +/- 10 counts or more, the last digit is not particularly significant. My conclusions are that this UT61E is an acceptable 2200-count DMM, but as a 22000-count device, the last digit is just there for entertainment. I would not trust it even in the short term for relative measurements.
I realize that I'm looking at a sample size of one, which is why I brought it to Martin's attention. Maybe I have a dud. Perhaps his sample will act better. Looking at teardowns and so forth, it does appear that this model has evolved internally.
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The first thing I noticed after opening the box was that it drifts quite a bit on DCV, and resistance is on the low side. For example, my 5V reference (stability verified with better equipment) may read 4.993V now and 5.002V later. Most of the time but not always, the excursions are within its specified accuracy. The most annoying thing is that this drift seems to be accentuated by using other functions. Example, take a DCV reading, then measure a resistance or a capacitor, then go back and take the same DCV reading, and it will be several counts different. It usually drifts back to the original reading within a minute or so.
My unit doesn't seem to have the problem you described, the DCV settles at a consistent reading very quickly every time, well, in the last few days since I've got it anyway. The warranty card that comes with it says the date of manufacture is 18 July 2012 so they may have had a few more mods since your batch. I do notice that it takes a while for the ACV reading to climb and settle though, but at least it's consistent. I have attached 2 pictures of the PCB in case anyone's interested in taking a look. Sorry about the lighting, I'm not a very good photographer.
One strange phenomenon I encounter though is that if I put the meter in ohm measurement mode, with leads plugged in but the probe tips not touching each other, display showing OL, and then unplug the positive lead swiftly from the socket, most of the time the bargraph would show a drop in reading, and the numerical display would sometimes capture values typically in the range of 1xx to 2xx M Ohms. Depending on which pair of leads I use I can sometimes even get the same fluctuation in readings simply by jiggling the leads! And I'm certain that the probes are not touching each other or any part of my body during the process. Normal resistance measurements are all within spec otherwise though.
Another issue I just found out is that in using the DMMcheck Plus for both DC and AC current measurements, if I use the mA range, the readings are pretty spot on (2-3 counts out or so on a 1.0000 mA reference). However, if I switch to the uA range, it would read 570-580 uA only instead of the expected 1000! I tried the same mA and uA comparison on my not-so-precise Chinese power supply, set it to a current limit somewhere between 1-2 mA, and the readings on both ranges do match each other for the most part. So is it because the DMMcheck's power being too low and the 61E's burden voltage too large on the uA range that it gives such hugely inaccurate reading?
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So is it because the DMMcheck's power being too low and the 61E's burden voltage too large on the uA range that it gives such hugely inaccurate reading?
Test with the Brymen too, and post a picture.
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My unit doesn't seem to have the problem you described, the DCV settles at a consistent reading very quickly every time ...
Thanks for the report. It may well be that I have an outlier on the performance curve.
One strange phenomenon I encounter though is that if I put the meter in ohm measurement mode, with leads plugged in but the probe tips not touching each other, display showing OL, and then unplug the positive lead swiftly from the socket, most of the time the bargraph would show a drop in reading, and the numerical display would sometimes capture values typically in the range of 1xx to 2xx M Ohms. ...
Mine does not do that at all. In any case, it does not sound like a serious problem.
Another issue I just found out is that in using the DMMcheck Plus for both DC and AC current measurements, if I use the mA range, the readings are pretty spot on (2-3 counts out or so on a 1.0000 mA reference). However, if I switch to the uA range, it would read 570-580 uA only instead of the expected 1000! ...
Same reading here, about 578uA. You are correct, it is due to the compliance voltage on the DMMCheck Plus being about 0.54V, which is not enough to overcome the burden voltage of the UT61E, which is roughly 1mV/uA, ie, a 1K-ohm shunt.
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So is it because the DMMcheck's power being too low and the 61E's burden voltage too large on the uA range that it gives such hugely inaccurate reading?
Test with the Brymen too, and post a picture.
The Brymen doesn't have the problem at all. mA and uA readings agree with each other on the DMMcheck Plus. What picture would you like me to post?
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The Brymen doesn't have the problem at all. mA and uA readings agree with each other on the DMMcheck Plus. What picture would you like me to post?
None, I believe you :-)
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I think I'm the one Martin referred to about warning of UT61E accuracy issues.
Yes...so thanks for posting your findings here as well as it will be a handy reference for others.
Cheers,
Martin.
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Oh, I forgot to mention another issue about the probes. Out of the box they seemed to have poor contact surfaces, not very responsive during the continuity test. Initial tests I did were mainly with other pairs of leads I have around. However, after giving the tips a good round of cleaning with some rubbing alcohol the problem is now solved.
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I see none of the problems you are having though, the +/- 10 counts might seem like it's going to be out of the box but WAIT, it's spec'd by UNI-T for 1 year drift. Frankly, 10 counts doesn't mean the last 10 counts are useless
BUT WAIT! That's on the AC voltage range.
A dear 87v is +/- 1 counts from 6V onwards (not sure about the "high-res" mode), this is 0.1% +/- 2 counts from 2 to 220V rated.
Point in point, 2 counts is pretty good for a meter that actually costs 30-35$ back in china. 35USD$? WOW
BTW, the MS8218 only costs 125USD back in china.
So now you know who's overcharging now? I can get the MS8218 on aliexpress for 150USD and frankly, that's a bit of a cheat but that's global shipping prices
as i can get the MS8218 sent to singapore for the first 500g at 5$ with the following 500g at 3$ and that's the 3 day shipping service (OF course, i have no idea who my china agent is shipping with), not the overpriced EMS rubbish
But really what's wrong with this meter? It's able to measure 220MHz! IT'S AWESOME.
Many things UNI-T got right with the meter itself,
Solid, doesn't creak when you turn it, some meters creak badly especially the BK 2709.
Doesn't slip around on a laminated surface when placed flat, i have a laminated surface right here
You can turn the rotary switch around without the meter rocking left and right
Well ... the LCD has oddly better contrast than the 87v, as well as a big display
when you do open it up, you can notice the design that went into the battery slot, as well how tightly it mates up with the body
as well when you look at how the shell on the bottom part goes right in between the front part, making a good blast shielding
They mount the LCD and it stays on the board and i have seen 50$ meters with the LCD gingerly hanging off the board
Solid feeling soft buttons
Fantastic rotary switch, frankly the only reason to love this meter is for the wonderful rotary switch, nice satisfying CLACK when you turn it off or the Amps range
and only a click on the other ranges
Lightning fast autoranging
Very fast continuity
Beeper is always on BUT the frequency is just about right.
Fast capacitance measurement, trust me, most 4000 count meters get this VERY wrong.
I just feel like the physical design team are 1000 times more competent than the design team of the electronics ...
Decent probes! They only cost 2-3 bucks back in china ... Only need to clean it when new but watch out, in a humid environment a layer of oxide can grow, i've seen even on my Wavetek (Very high quality!) probes
Also to note, the wall of the meter is pretty thick, as with the thickness of the back itself, physically this thing is a beast, sort of.
But i have seen flukes with worser physical qualities, did they hire building designers or what?
I'll say the integrated holster is a nice thing (easier to access battery and fuses), as with the battery + tilting bail
And ... this is the first meter i had that smells VERY nice, the plastic's smell if both of mine do fade away, i am tempted to buy another one ... just for the smell
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Some follow-up information:
I decided to have a go at calibrating my unit's DC voltage range. I used 2.10V and 21.0V sources monitored with a bench meter, and adjusted for best results between the two. The trimmer pot was very finicky, but after exercising it a bit I got reasonable results. The meter seems to drift less than it did before, my theory is the trimmer pot may have been a little shaky from the beginning.
The last digit will never be particularly meaningful in terms of absolute accuracy, but as long as the meter is stable, the LSD can be useful for observing short-term trends. My unit was not that stable at first, but it seems a little better now.
During the DIY calibration exercise, I found that if the meter is in ACV range with auto-ranging on, probing a DC voltage of more than about 10V will cause the meter's auto-ranging algorithm to fail with lots of beeping and flashing.
I decided to check the unit's AC performance a little further, since measuring AC in the presence of a DC offset is not exactly an uncommon scenario in electronics. DC power supply ripple, an audio signal in an amplifier, etc.
My test signal was a 200mV rms sine on top of a 10V DC offset, provided by a function generator. On DCV I got a correct display of 10V. On ACV with auto-ranging, I got the crazy display. With manual ranging, I eventually got a correct reading of 0.2V after a long settling time. On the ACmV range, I got unstable readings in the area of 25 mV. It would only produce the correct value of 200mV if I reduced the DC offset to less than 2V.
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Oh yeah, don't forget the multipurpose socket as they are so called. It's a meter world first ::)
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And ... this is the first meter i had that smells VERY nice, the plastic's smell if both of mine do fade away, i am tempted to buy another one ... just for the smell
Mmmm.
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It would only produce the correct value of 200mV if I reduced the DC offset to less than 2V.
Your story motivated me to test under the same conditions the Agilent U1273A.
I did the test at 200Hz sinusoid 600mV / and tested it with +5 & -5 DC offset, no problem.
When I did try to lower down the output to 200mV by inserting attenuation filters, my function generator was capable to output 200mV but only +/- 1,5V DC offset.
http://www.ittsb.eu/my%20bench.html#PHILIPS (http://www.ittsb.eu/my%20bench.html#PHILIPS)
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Your story motivated me to test under the same conditions the Agilent U1273A.
I did the test at 200Hz sinusoid 600mV / and tested it with +5 & -5 DC offset, no problem.
When I did try to lower down the output to 200mV by inserting attenuation filters, my function generator was capable to output 200mV but only +/- 1,5V DC offset.
Interesting, thanks. I would fully expect Agilent to get it right. I tested many Fluke meters here, and all of them were able to read the 10VDC and 200mVAC components of the signal without problems.
I forgot to mention my test signal was 200Hz as well. I chose 200mV just so that I could test the 220mV range of the UT61E.
You can insert more DC offset if you wish, by putting a battery in series with the FG output. But you probably knew that already, it just makes a mess with the cables.
Along with a basic ACV bandwidth check, I think an 'ACV with DC bias' test might make a good addition to multimeter performance tests.
BTW, nice function generator!
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Along with a basic ACV bandwidth check, I think an 'ACV with DC bias' test might make a good addition to multimeter performance tests.
In my review about the Agilent U1272A I did wrote that if I detect DC volts mixed with AC in one AC Mains plug I would feel strange, like to had see a Ghost. ;D ;D
I did wrote that mostly, so to point out, that electricians favor (or better said) .. appreciate differently its feature found on a multimeter.
I would expect from the people who claim to be more experts to electronics, to do such tests.
BTW, nice function generator!
Thanks mate.
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Martin demonstrated on Youtube that the UT-61E showed some nasty overshoots in the measured value that was also sent to the PC logging. Is there any explanation found, and/or a remedy for this? Does the same phenomina also show in the UT-61D?
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Martin demonstrated on Youtube that the UT-61E showed some nasty overshoots in the measured value that was also sent to the PC logging. Is there any explanation found, and/or a remedy for this? Does the same phenomina also show in the UT-61D?
It's an autoranging glitch. The 61D most likely does not show the same behaviour, not only is it deathly slow but it's electrically entirely unrelated to the 61E.
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Hello Gents,
First post so please be gentle. I purchased a UT61E a while back (thanks Franky). My new computer does not have a serial port, only usb’s. Ok, need a serial to usb adapter. While checking on Ebay I found this http://www.ebay.com.au/itm/UNI-T-Multimeter-USB-Data-interface-cable-UT-D08-replace-UT-D04-for-Windows-7-XP-/130743143940?pt=AU_B_I_Electrical_Test_Equipment&hash=item1e70e60e04 . You beauty, won’t have to mess around joining up leads to adapters. The unit is the same as a Silicon Labs CP2104 USB to UART Bridge controller and as such you will also need : Leadtek_GPS_Driver.zip so your computer will recognise the lead hook-up. And yes I know it’s a gps driver, but it works. Apparently some GPS units use the same technology.
Hope this info helps someone.
Cheers Neville
:)
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Forgot this. Where I downloaded the software from. :D
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Thanks for this, amazing what ya can get working just by trying a few things ain't it ? :)
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Thanks for this, amazing what ya can get working just by trying a few things ain't it ? :)
G'day Majes,
Glad to help. It took quite a bit of searching and hair pulling to find something that actually worked and as you said trying a few things and vwalla, it worked
cheers Neville
;D
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I found a new sensitivity issue with ut61E.
A reverse bias in capacitance range (>3 volts) even with small current (<1mA) will make the processor freeze and display all segments and will increase current draw from its internal battery. This doesn't happen with normal bias and the meter displays a "discharge cap" message. So be extra careful with this function when measuring caps that may have even a small voltage on them.
True rms accuracy with square wave at low voltage:
1.64v (high on range):
20 hz 1.634
40 hz 1.641
400hz 1.645
4khz 1.644
20khz 1.653
40khz 1.664
75khz 1.679
120khz 1.667
150khz 1.593
2.4v square wave(low on range):
20hz 2.400
40hz 2.412
400hz 2.415
4 khz 2.385
10khz 2.344
20khz 2.295
40khz 2.188
62khz 2.100
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an amazing device! is unique at this price! ;D
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and how much will be accurate if the measured resistance is less than 1 ohm?
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I did a quick upgrade of my one today, and added the input protection it should have had ( on the PCB but omitted for cost reasons) by adding 4 275V varistors in the required locations. I used 2 in series for each poswition, so now the input will be clamped for any voltage over 830V DC peak, as I selected the varistors for equal breakover voltage. I found a pack of RS 204-1996 275VAC varistors i had ordered long ago, and checked all 5 to see breakover voltage. 2 were 402/3V, and 2 were 425/7V, with the one being 411V, so I used the high and low in series, so each chain has a similar breakdown voltage. Did not dismantle the meter, just soldered the pretinned and precut and preformed ends into the holes in the PCB, and then joined the midpoints of the 2 strings, so that they were floating in the air inside. Placed the varistors neatly in the space and closed it up again.Checked on resistance, and still reads open circuit, so no problems there. Was debating doing a high pot test but as they have been tested before use decided against it, they should work. I know the little green tester from Frankie can deliver 1400V as a test voltage, but I still like the meter. Ohers have tested them to destruction, and the PCB breaks down at around 1500V so I am happy enough.
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I did a quick upgrade of my one today, and added the input protection it should have had ( on the PCB but omitted for cost reasons) by adding 4 275V varistors in the required locations. I used 2 in series for each poswition, so now the input will be clamped for any voltage over 830V DC peak, as I selected the varistors for equal breakover voltage. I found a pack of RS 204-1996 275VAC varistors i had ordered long ago, and checked all 5 to see breakover voltage. 2 were 402/3V, and 2 were 425/7V, with the one being 411V, so I used the high and low in series, so each chain has a similar breakdown voltage. Did not dismantle the meter, just soldered the pretinned and precut and preformed ends into the holes in the PCB, and then joined the midpoints of the 2 strings, so that they were floating in the air inside. Placed the varistors neatly in the space and closed it up again.Checked on resistance, and still reads open circuit, so no problems there. Was debating doing a high pot test but as they have been tested before use decided against it, they should work. I know the little green tester from Frankie can deliver 1400V as a test voltage, but I still like the meter. Ohers have tested them to destruction, and the PCB breaks down at around 1500V so I am happy enough.
nice mod! any pics or can you show the mod on the original circuit diagram?
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When I get the chance I will post the photo. It is in the camera..........
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Here it is...
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Many thanks for posting the pic!
It just shows how much of a beginner I am, I had to look up "varistor", then realized it's actually a MOV. Another really helpful thing was I didn't know the 61E used a Cyrustek chipset which is what I'm working into my DMM project, so looking at the 61E schematic is an extremely useful practical circuit, which is much better than the chipset datasheet examples.
I have a question though, in the datasheet it talks about the parasitic capacitance of the PCB; would the mod you did effect that to a point you'd need to tweak the trimmer cap on the board to compensate? have you checked the low value cap measurements; are they working ok?
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Here it is...
It's interesting that on the pcb there are GDT symbols instead of MOVs. However, I think MOVs are a better choice due to the fast response.
How did you choose the 2 x 275V MOV? Simply because that's what you had and 830VDC peak seems too much for your needs anyway? I'm asking because the meter is intended to measure 1000VDC and 750VAC (1050VDC peak) so you're kind of inhibiting functionality here.
In Dave's #373, the Fluke 27 has 4 x 430V MOVs, so it clamps at 1700V, even though it only measures up to 1000V
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They were on hand, and were the right size to fit. They add about 50pf across the input, which will not affect the meter much. This is not going to affect the voltage divider, as it is before it. GDT tubes would probably be better as they clamp at around 90V when conducting, keeping high voltages out and making sure the PTC units will operate. Using the MOV's though will just clamp, and they have a limited power dissipation capacity of 0.2W so a long term overload will burn them out. Short term will be no problem though, it is just there for operator oopsies.
As I generally do not deal with more than 600V the value chosen is good enough for me.
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I'll have to post up a fresh picture of my UT61E. GDTs fitted, as well as upgraded fuses (they were laying around).
E: Here we are.
E2: And now Farnell's back from their regular maintenance RIGHT WHEN I WANT TO USE THEM, EVERY NIGHT: http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=2118242
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I was looking to use some of those, but was waiting until I had an order big enough to make the postage free from RS, the VDR's were a previous order where I just needed 1 in the 5 pack, so I used them instead.
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Monkeh:
That is the way they should have built it in the first place!
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Monkeh:
That is the way they should have built it in the first place!
That was the idea :)
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Hi can you tell me the fuse's rating that you used.......many thanks 8)
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RUNNING UNI SOFTWARE SIMULTANEOUSLY IN SEVERAL INSTANCES ON WIN7
Hi folks
I do not own a UT-61E yet ... thus the question.
Can I run the logging software for the UT-61E in several instances on WIN 7 ???
iow I need to log three different values at the same time and I would like to use 3 UT-61Es
Thanks for any help
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You should be able to... just get three serial to usb adapters/cables, they'll create 3 separate virtual COM ports in Windows, you start three instances of the application and set each one to a different COM port. No problem at all.
See UltraDMM software, it may be able to run three at same time without having to run three applications.