Multimeters

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Timo42

Timo42

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Mar 26, 2007
1,042
Venture 22 Marina del Rey
I find I use a Powerprobe more than my Fluke, it has the additional benefit of being able to inject power or ground into the circuit, and it has really long leads so you can check voltage drop from the battery to whatever you are testing. http://www.powerprobe.com/powerprobe/PP3.html Tim
 
John Nantz

John Nantz

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Jul 1, 1998
3,062
Hunter Legend 35 Poulsbo/Semiahmoo WA
Cheap vs Pricy (i.e., vs Fluke)

Read through all these posts and I've got a bit of deja vu.

Earlier this year I couldn't find my Fluke 77 multitester (cost ~$170 at discount several years ago). I looked absolutely everywhere and suspected I may have left it on the dock after doing some work on the boat.

The 77 was the most accurate meter in it's series at the series at the time and for years (about 20 to 25 years ago) was the "standard" by which other similar instruments were judged.

Moving ahead several months I was talking to a guy who worked for the FAA and ran their test lab where he calibrated the test instruments for other FAA electronic technicians. I told him my sob story about loosing the Fluke and he said to save my money and buy this cheapie for $3.89 at this store in Tacoma. Huh? $3.89? I don't think so! I wanted something good!

Trust me, he said, it will do what I want and it's a LOT cheaper. After checking all possible resources for another meter I broke down and bought this "thing" (big spender). It's a Kupp (or Kopp) GDT-190A.

Don't know if this has ever happened to anyone else, but a few days later I found my Fluke!!! See, this works!

The next step was to check out this cheapie. We bench tested several of the functions against the Fluke 77 and ... surprise! ... it was REALLY accurate! Now I have one I leave on the boat all the time.

Google GDT-190A and you'll get a number of hits. I can't remember the name of the store in Tacoma that sold these but they are a chain store that sells tools and other stuff imported from (*yikes*) China.

Caveats:

GDT-190A: It is made in China. Therefore; read "lead" in the plastic. Use gloves when handling or wash hands after use.

Fluke 77: Do NOT blow the fuse! They are EXPENSIVE (for a fuse) and hard to find. You can probably buy three 190As for the price of one Fluke fuse!
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,677
Canadian Sailcraft 36T Casco Bay, ME
Accuracy????

A slew of cheap meters all connected to the same exact battery.. Hmmm.....

 
Timo42

Timo42

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Mar 26, 2007
1,042
Venture 22 Marina del Rey
Jeeze Mainsail you are like a man with 2 watches, never sure what time it is:D
I would say that if you need absolute measurements, for power consumption calculations etc, spend the money, if you are troubleshooting, and all you are looking for is the difference between readings, get a cheapo, as far as finding lost tools the day after you buy a replacement, it always works that way. :doh:
Tim
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,677
Canadian Sailcraft 36T Casco Bay, ME
Timo42 said:
Jeeze Mainsail you are like a man with 2 watches, never sure what time it is:D
I would say that if you need absolute measurements, for power consumption calculations etc, spend the money, if you are troubleshooting, and all you are looking for is the difference between readings, get a cheapo, as far as finding lost tools the day after you buy a replacement, it always works that way. :doh:
Tim
Click to expand
BTW thanks for reminding me that I need to get one of my my Fluke's back from my dad.. I think he's had it now for about 8 months?? I bet he remembers when it was the other way around, me borrowing tools from him..

On a meter that does not run out to the hundredths, like a Link 10 or Xantrex XBM, that represents the difference between 12.4 and 12.5 volts. If looking for a milliamp voltage leak, as I was the other day with Tim R., that can be a decent difference.
 
sailingdog

sailingdog

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Oct 22, 2008
3,502
- Telstar 28 Buzzards Bay
The real question is what is the actual voltage of the battery in question? 12.415 volts, or 12.475 volts... or something in-between???
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,677
Canadian Sailcraft 36T Casco Bay, ME
sailingdog said:
The real question is what is the actual voltage of the battery in question? 12.415 volts, or 12.475 volts... or something in-between???
Click to expand
My point exactly... The Mastech and A.W. Sperry are usually the closest to my Fluke, but not quite (Fluke is NIST calibrated), and the Mastech and Fluke occasionally agree out to the hundredths.. In defense of the UEI it has been dropped to many times to count. As for the other meter, reading 12.41, the Etek, well.... you get what you pay for.

EDIT: My Mastech has literally fallen apart over the last year. It will no longer zero, the clamp jams, the light died and its calibration has drifted. So much for a cheap "DC clamp"...
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Significant digets

Way back when dinosaurs roamed the earth and I went to high school we learned about a curious thing called the number of significant digits. MOST engineering only uses 3 significant digits so I'd say they are all in good agreement with 2 reading over the third digit and 2 reading below it after rounding.
That 0.02 volts could easily be the connection of the probe and not the meter proper Try going to a lower voltage scale to shift the significant digits to the right. Course you are still measuring 12 something so that is always going to eat up 2 of the digits.
 
dvideohd

dvideohd

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Jul 24, 2005
261
MacGregor Mac26D Richardson, TX; Dana Point, CA
there are other factors to consider in connecting a voltmeter...

Main Sail's picture points it out....

a - there is the lead length and connection to consider. Lead lengths can matter. Higher end voltmeters will have a "zero adjust" to let you "factor in" the connection length of wire and end connector type... the "Sharp pokey" type probe will not be as accurate as the more sophisticated clip or 4 wire type attachment.

b - each position on a DVM can have a different "zero point"... I have goofed before where I would "zero" with one setting - and then change to another... only to find out that is was off being "zeroed"...

c - the DVMs themselves will vary on the last part of the precision... if you want 3 digits of accuracy - then get a 4 digit meter..

d - temperature and aging do matter... so occasionally compare against a known reference if it matters...

with a lot of electronics now, the extra precision is very achievable... but - like the analog meters - you still have to consider the system you are measuring and how you connect.

It could also be that leakage will diddle your readings.. so isolating the device under test is a good thing... if necessary....

--jr
 
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