Author Topic: Bunch of keysight U1252B meters around  (Read 104984 times)

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tooki

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Re: Bunch of keysight U1252B meters around
« Reply #425 on: June 09, 2017, 04:48:01 pm »
Please educate this dumb dirty ape, tooki.  What is the error of this meter?  I read the spec sheet that says 0.05+10 in the 500 ohm range, which should be .05% but I don't get the +10 part.  Can this meter measure 0.1 ohms accurately?
The +10 means ten counts, and the % means % of full scale (for the range). So in the 500 ohm range, that means an error (in either direction) of 0.05% of 500.00, which is 0.25 ohms, plus an error of 10 counts either way. Since on that range, there are two decimal places, this means that on that range, the 10 count error means 0.1 ohm.

So for example, with a device that's exactly 100.00 ohms, the spec says the reading could be anywhere from 99.65 ohms (100-0.25-0.10) to 100.35 ohms (100+0.25+.10) and be within spec. Edit: More experienced folks: Am I correct on this? Or is the % error actually % of the DUT, e.g. 100-0.05-0.10=99.85 ohms through 100+0.05+0.10=100.15 ohms?

I still want you to attempt to explain what you think resolution means. Your final question there is still indicating that you don't.
« Last Edit: June 09, 2017, 05:10:16 pm by tooki »

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damn_dirty_ape

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Re: Bunch of keysight U1252B meters around
« Reply #426 on: June 09, 2017, 04:50:39 pm »
Thanks for that explanation, both tooki and grump

I think resolution is a bit like dynamic range, as in the smallest step that the reading will change by.  I don't think this is related to accuracy, but to the precision of the instrument.

tooki

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Re: Bunch of keysight U1252B meters around
« Reply #427 on: June 09, 2017, 04:56:14 pm »
Yep, resolution is the size of the steps. So you can't realistically expect to measure things that are only as large as a few of those steps.

That's why I was asking what the "small resistances" are that you want to measure. If you wanna measure 100 ohm resistors, this will work great. If you want to measure 1 ohm resistors, you really need a different tool.

BTW, don't think that 4-wire resistance is prohibitively expensive; a Keithley 197, for example, can be had for around a hundred bucks.

damn_dirty_ape

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Re: Bunch of keysight U1252B meters around
« Reply #428 on: June 09, 2017, 05:06:36 pm »
Nice, thanks for the suggestion.

The way I understand it now, this meter can measure to about +- 0.25 ohms, which should be great for me.  Plus data logging, signal generator, I'm excited   Thanks for the help!

grumpydoc

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Re: Bunch of keysight U1252B meters around
« Reply #429 on: June 09, 2017, 05:07:24 pm »
The +10 means ten counts, and the % means % of full scale (for the range).
Nearly - the 0.05% is of the reading, not full scale.

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tooki

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Re: Bunch of keysight U1252B meters around
« Reply #430 on: June 09, 2017, 05:11:32 pm »
The +10 means ten counts, and the % means % of full scale (for the range).
Nearly - the 0.05% is of the reading, not full scale.
Heh, thanks! You wrote this literally as I was editing my post to ask this very question!!!!

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Re: Bunch of keysight U1252B meters around
« Reply #431 on: June 10, 2017, 08:49:51 pm »
Mine finally arrived today.  Cal 12/2011.  Oldest I see in this thread.  The whole thing has a slightly "musty basement" smell.
Same here.  Same cal date; same musty smell.  It was between the U1252B and the Brymen 869s -- for roughly the same price.  I wanted the 20MHz frequency counter in the U1252B.  If it were not for that one feature, I'd have gone for the Brymen.

Now I'm just waiting for the next batch of EEVBlog DMMs to show up on Amazon.

Fraser

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Re: Bunch of keysight U1252B meters around
« Reply #432 on: June 10, 2017, 09:19:00 pm »
My meter just arrived

It is in new condition with no musty smell or evidence of exposure to damp.

Calibrated in 2012.

The supplied battery is being changed for a nice fresh Varta 'low self discharge rate' Ni-Mh replacement

Fraser
« Last Edit: June 11, 2017, 12:27:21 pm by Fraser »

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Re: Bunch of keysight U1252B meters around
« Reply #433 on: June 11, 2017, 12:40:47 am »
The frequency counter on this U1252B is very accurate.  I'm testing it with my SDG2000X and it's giving me perfect results up to 20MHz.

Fraser

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Re: Bunch of keysight U1252B meters around
« Reply #434 on: June 11, 2017, 02:27:27 pm »
My U1252B has passed its testing today without any issues. The original Powerex '9V' battery was reading only 2.6V upon arrival. No surprises there , and due to the long storage period. When being charged it multi-tripped the delta V monitoring smart charger at between 10mAh and 25mAh capacity ! I now have the battery charging very gently on a CC lab power supply to bring all the cells up to full charge. I will check the batteries cell balance and capacity on my analyser later. I have fitted the nice new and fresh LSD VARTA 8.4V battery and that will remain in the meter.

In case any readers are unaware..... the Powerex is a 7.2V 300mAh conventional Ni-Mh battery. It is not a low self discharge type. This means that it will discharge over a period of months, even if not used. I purchased a VARTA (Made in Japan) 8.4V 200mAh Low self Discharge (LSD) battery. I understand the cells in this VARTA branded battery are Sanyo Eneloops.
Make sure you buy one made in Japan and not China though as the Chinese versions do not use Sanyo Eneloop cells.

Fraser
« Last Edit: June 11, 2017, 07:28:10 pm by Fraser »

mark03

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Re: Bunch of keysight U1252B meters around
« Reply #435 on: June 11, 2017, 07:22:18 pm »
My U1252B arrived yesterday with a cal date of 9/2011 (a new record?) and very strong musty/moldy smell.  I replaced the battery with a new Powerex 8.4V/300mAh and turned it on.  First impression, wow, the low digits really zoom around---I'm only used to cheap slow meters.

Unfortunately there seems to be a problem.  Measuring the old Powerex battery, I got 37 mV.  Strange, let's try a fresh AA cell.  Also 37 mV.  Switching to manual ranging, I get 3.7 mV on a low range, 37 mV on the next, 370 mV on the next, then approximately correct readings (1.5x V) on the highest ranges.

It was easy to open the case and examine the PCB so I did, and despite the strong odor I cannot see any obvious signs of water damage or residue.

Anyone know if these symptoms are indicative of a bad calibration, or something more serious?

rattnallen

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Re: Bunch of keysight U1252B meters around
« Reply #436 on: June 11, 2017, 08:24:57 pm »
My U1252B seems to work ok except in the MOhm ranges.

When testing with 5*1MOhm in series I get 4.0155MOhm in the 5MOhm range, 8.767MOhm in the 51MOhm range and 8.77MOhm int the 510MOhm range
When checking whitn another DMM I get 4.92MOhm.

Calibrated 06/2013.

ocw

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Re: Bunch of keysight U1252B meters around
« Reply #437 on: June 11, 2017, 09:26:43 pm »
Quote
My U1252B seems to work ok except in the MOhm ranges.

My U1252B measured a 1.000M 0.01% resistor as 0.99990M (-0.01%).  It measured a 100.0M 0.5% resistor as 100.04M (+0.04%).  I measured the DC voltage, AC voltage and resistance accuracy of my U1252 (Keysight calibrated 05Feb2015) as:

VDC           % Error
24.993 mV     0.0104%
50.053         0.0014
74.97           0.0004
100.02         -0.0028
249.82         -0.0144
500.33         -0.0094
0.7496 V        0.0185
0.9999         -0.0008
1.2504         0.0335
1.8002         0.0133
2.0480         0.0005
2.4999         0.0032
2.9978         0.0090
3.3003         0.0067
4.0961         0.0039
5.0001         0.0012
7.494           -0.0081
9.998           -0.0108

VAC          % Error
3.5380 V         0.070%
Frequency Accuracy:  -91 PPM

OHMS         % Error
0.21             5.0000%
0.99             -1.0000
5.01             0.2000
10.00           0.0000
49.99           -0.0200
99.98           -0.0200
249.91           -0.0360
349.94           -0.0171
499.9           -0.0200
1,000.0           0.0000
2,499.9           -0.0040
5,000.0           0.0000
8,999            -0.0111
9,895            -0.0505
10,001           0.0100
49,890           -0.0200
100,010           0.0100
0.99990M        -0.0100
100.04M           0.040

Not having a feedback mode for current measurement, those readings had significant errors when the effects of its 101, 2.3 and 0.045 shunt resistors where not taken into account.  The corrected readings met its specifications.  I think we now have the parts available to add the feedback mode in meters without having a huge increase in the complete meter price.

bitseeker

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Re: Bunch of keysight U1252B meters around
« Reply #438 on: June 12, 2017, 02:07:52 am »
Updated my previous post with links to the "A" series listings.

https://www.eevblog.com/forum/testgear/bunch-of-keysight-u1252b-meters-around/msg1225433/#msg1225433

Disclaimer: These are not my listings nor inventory. I'm just a fellow purchaser.
I TEA.

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mtdoc

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Re: Bunch of keysight U1252B meters around
« Reply #439 on: June 12, 2017, 02:58:13 am »
My U1252B seems to work ok except in the MOhm ranges.

When testing with 5*1MOhm in series I get 4.0155MOhm in the 5MOhm range, 8.767MOhm in the 51MOhm range and 8.77MOhm int the 510MOhm range
When checking whitn another DMM I get 4.92MOhm.

Calibrated 06/2013.

I would try going through the calibration procedure which can be found in the manual (available online). It's easy to do. My second meter was slighly out of spec so I did the calibration and it brought it back into spec. You will need another reliable DMM, stable power supply and resistors to produce the required voltage and resistor values.

bsudbrink

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Re: Bunch of keysight U1252B meters around
« Reply #440 on: June 12, 2017, 04:17:26 pm »
My U1252B arrived yesterday with a cal date of 9/2011 (a new record?) and very strong musty/moldy smell.
On mine, that seems to have cleared out of the meter and leads pretty quickly.  Were the staples on your quick start guide rusted?

I replaced the battery with a new Powerex 8.4V/300mAh and turned it on.
After a couple of charge/discharge cycles, the battery supplied with mine seems to be behaving itself.

First impression, wow, the low digits really zoom around---I'm only used to cheap slow meters.
I'll add a "me too".  On the low resistance ranges, I can get the digits "zooming" just by shaking the leads around.

Unfortunately there seems to be a problem.  Measuring the old Powerex battery, I got 37 mV.  Strange, let's try a fresh AA cell.  Also 37 mV.  Switching to manual ranging, I get 3.7 mV on a low range, 37 mV on the next, 370 mV on the next, then approximately correct readings (1.5x V) on the highest ranges.
I put a couple of batteries on mine and seemed to get reasonable measurements.  I'll hook it up to my bench supply tonight and test a little more extensively.

It was easy to open the case and examine the PCB so I did, and despite the strong odor I cannot see any obvious signs of water damage or residue.
I haven't opened mine up in case I have to send it back.

I want to add that I got a very nice email from the seller, nmori87-us, indicating that he reads (or is made aware of) this forum and will stand behind these meters if there is a problem.

bitseeker

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Re: Bunch of keysight U1252B meters around
« Reply #441 on: June 13, 2017, 02:26:38 am »
I want to add that I got a very nice email from the seller, nmori87-us, indicating that he reads (or is made aware of) this forum and will stand behind these meters if there is a problem.

Good to hear, bsudbrink. I've been conversing with nmori periodically, so he is aware of this thread and our e-community. I'm sure he's sold quite a lot of meters here and does want them to work out for everyone.
I TEA.

mark03

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Re: Bunch of keysight U1252B meters around
« Reply #442 on: June 13, 2017, 03:39:51 am »
My U1252B arrived yesterday with a cal date of 9/2011 (a new record?) and very strong musty/moldy smell.
On mine, that seems to have cleared out of the meter and leads pretty quickly.  Were the staples on your quick start guide rusted?
Yes, very rusted.  I hadn't noticed until just now.

Unfortunately there seems to be a problem.  Measuring the old Powerex battery, I got 37 mV.  Strange, let's try a fresh AA cell.  Also 37 mV.  Switching to manual ranging, I get 3.7 mV on a low range, 37 mV on the next, 370 mV on the next, then approximately correct readings (1.5x V) on the highest ranges.
I put a couple of batteries on mine and seemed to get reasonable measurements.  I'll hook it up to my bench supply tonight and test a little more extensively.
Let us know how it performs.  It's encouraging that the seller would take a return if necessary, but I'd really like to avoid that.  I was hoping someone would chime in with knowledge about how the calibration system works.  The way mine is behaving doesn't seem like it could be explained by component drift.  But if the calibration constants are kept in nonvolatile storage, and that were corrupted somehow...?

I don't have the equipment here for even a rough calibration, so I'd rather not go down that route unless there is reason to believe that the errors I'm seeing could originate in the digital domain.  If the root cause is analog in nature, I'd be much less optimistic.

bsudbrink

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Re: Bunch of keysight U1252B meters around
« Reply #443 on: June 13, 2017, 03:41:05 pm »
Ok, I put three 1K resistors in series as a load and ran it through its paces.  My supply is a Siglent SPD3303X-E (Yea, yea, I didn't use banana leads!) so I have "resolution" down to 10mV from the supply and 3.333mV in the load.  I got a consistent 4mV disagreement between the 3303 display and the 1252 across the load.  That is for example, the 3303 display said 1.27 and the 1252 said 1.2662 with the last digit "wiggling around".  Like several others in the thread, this is by far the most precise instrument I own and I'm not yet familiar with it, but I assume that the discrepancy is the voltage drop across the wires between the 3303 and the load.  I got expected values inside the load (1/3rd or 2/3rd of the total).  So, all-in-all, it looks like my 1252 is good for DC volts.  Sorry about yours.

BMCha

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Re: Bunch of keysight U1252B meters around
« Reply #444 on: June 15, 2017, 03:10:17 am »
I've been thinking about picking one of these up.

As discussed earlier, the current listings have both the 1252A and 1252B. Looking at the posted datasheets the only real difference for the A from the B, other than extra frequency support in the high AC ranges, seems to be the higher input impedance at low voltages.

1) are there any practical issues that would arise from the impedance difference? I'll admit that I'm not too knowledgeable about what that means for the DMM's capabilities.
2) is there anything else I'm missing? If the minor datasheet differences aren't important, it looks like the A might be a good choice -- seems to come with a few extras and despite it's being older I'm getting the impression that the cal dates on the B's are around the same time by now.

Also despite rereading the last few pages I'm having trouble telling whether the current batch of B's is having problems or not (and who knows about the A's). I see that the seller is going to stand behind the products but I'd like to avoid any defect problems if possible. Should I be worried about anything here?
Finally, (hope I'm not asking too many questions here) does the older cal date have any practical consequences for a hobbyist use-case? I like the high count and accuracy figures for these meters, but if they've drifted too far out of spec that's somewhat moot (and I don't have the equipment to do a nice calibration myself). It sounds like most people have been getting good results but the cal dates appear to be sliding backwards as the seller goes through stock.

Thanks!

PTR_1275

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Re: Bunch of keysight U1252B meters around
« Reply #445 on: June 15, 2017, 06:25:29 am »
I just bought a U1177a Bluetooth module for my meter, the instructions are vague but seem simple. Turn on, connect via iPhone or iPad settings (Bluetooth), pair, open app and use it.

However I cannot connect via my iPhone or iPad and am pulling my hair out a bit. My mate can see it with his android phone. Is there anything that I'm missing? Anyone here have the Bluetooth module and had the same issue?

BravoV

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Re: Bunch of keysight U1252B meters around
« Reply #446 on: June 15, 2017, 07:58:49 am »
I just bought a U1177a Bluetooth module for my meter, the instructions are vague but seem simple. Turn on, connect via iPhone or iPad settings (Bluetooth), pair, open app and use it.

However I cannot connect via my iPhone or iPad and am pulling my hair out a bit. My mate can see it with his android phone. Is there anything that I'm missing? Anyone here have the Bluetooth module and had the same issue?

PTR_1275

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Re: Bunch of keysight U1252B meters around
« Reply #447 on: June 15, 2017, 08:04:22 am »
Ahhh crap. I didn't find that in anything I looked at.

tooki

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Re: Bunch of keysight U1252B meters around
« Reply #448 on: June 15, 2017, 08:58:33 am »
I just bought a U1177a Bluetooth module for my meter, the instructions are vague but seem simple. Turn on, connect via iPhone or iPad settings (Bluetooth), pair, open app and use it.

However I cannot connect via my iPhone or iPad and am pulling my hair out a bit. My mate can see it with his android phone. Is there anything that I'm missing? Anyone here have the Bluetooth module and had the same issue?

How odd, given that iOS has had robust Bluetooth support for a long time, and that both the 1177A and 1117A use the same Bluetooth profile. (It's not that the 1177A uses a weird Bluetooth type, either, it's just BT 2.1.)

BravoV

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Re: Bunch of keysight U1252B meters around
« Reply #449 on: June 15, 2017, 09:08:22 am »
How odd, given that iOS has had robust Bluetooth support for a long time, and that both the 1177A and 1117A use the same Bluetooth profile. (It's not that the 1177A uses a weird Bluetooth type, either, it's just BT 2.1.)

I'm guessing its more business decision/reason rather than technical one, cause the 1177A product is quite old, and Keysight probably just doesn't want to re-invest more to develop IOS application for it.

If I'm not mistaken, this 1177A was released when they just acquired the Escort brand and the whole DMM business, re-branded all Escort's meter, and Agilent (before Keysight) was just starting the handheld DMM business.

Remembered this quite well when 1177A was released many-many years ago, IOS was not supported from the beginning.

Smf