Fluke 25 - My first Digital Multimeter

[Kibi]

Hi everyone.
I thought I'd base my first post on something else that was first for me.
When I was a little boy.............., my dad found this Fluke 25 in a general second hand shop, and bought it as a birthday present for me. I have owned it for about 20 years now and it is still going strong. I has suffered some really hard knocks but works 100%. It's calibration is pretty spot on too.
What makes this one a bit special I think, is that it is the only Fluke 25 I have ever seen like it. It is MSHA (Mine Safety and Health Administration) approved and has a yellow case instead of the brown which is more common.
I just wondered if anyone else has seen a yellow Fluke 25 before or if anyone knows a little bit more about it's history.

Here are a couple of pictures.






If anyone fancies seeing some more pictures of the innards, then I'll get on the case, perhaps do a mini review of it.

[Kiriakos-GR]

I had inherit from my father an Japanese analog multimeter , sadly I killed it by RF ,
and I was only 16 and unable to repair it.

But today I own lots of his tools, so to remember him.   

[Excavatoree]

Helo Kibi, and welcome!

I have two or three of the 25 model in the yellow case, and several more various versions of this meter. 27, 27/FM, 25 in green case, etc.)

I don't know much about the history, but I'll tell what I do know, and what I can theorize from the many examples I have seen.

The first generation meters:
These were the 8025a and 8025b.  They were dark greenish brown, or maybe it is brownish green.   These were only made for the US government.

Tbe only difference between the two is that the 8025a is missing the two center buttons. (Max/Min and Rel)  Oddly, the internal circuit boards are the same - an 8025B front case and rubber button assy will turn a 25/8025a into a 27/8025b.

The second generation meters:
These were the 25, 27 and the 27/FM.  The 25 is just like the 8025a, and the 27 is just like the 8025B.  (Only the 27 has the center two buttons - Max/Min and Rel.)  All were still in the brownish green case.  The 25 and 27 were sold to the civilian market.  The 27/FM was only sold to the military.  I'm not sure of the exact timing, which came first, if there was any overlap with the 8025's, etc.

The military model of the 27, the 27/FM is the only meter of this type with the "True RMS" feature.  There is actually an extra IC in the meter labeled "Fluke RMS."

The third generation meters:
These had yellow cases instead of the green.   Models were still the 25 and 27.  I'm not sure if there was any overlap of any of the green models with the yellow.  These yellow meters were sold to civilians for use in mines, and, as you note, were rated by the MHRA.  I've never seen a green one with that rating, but, all of these are the same, with the exception of the True RMS feature of the 27/FM.

There is "sort of" a 27/FM yellow meter, but "27/FM" appears only on a sticker on the back.  These latest government meters of this type look just like the civilian, yellow, 27 meters on the front.   Like all civilian 25s and 27s, these are NOT true rms.  (very confusing - to keep it straight, I don't call these 27/FMs, I only call the true RMS version a 27/FM.  That is, I go by the mainboard, not the sticker on the back)

Also, sometime in the "third generation," the Fluke logo was changed from the Fluke enclosed by the white rectangle with lines below to just the word FLUKE in a larger font.

These yellow meters were sold  until a year or so ago, when the 27-II and 28-II were introduced to replace them.  The 27-II is not true RMS, the 28-II is.

 Dave has a great review of the 28-II in which  he took one canyoning.  He had to work pretty hard to damage it, and it was repaired easily.  (broken LCD, broken inductor)  Looks like the new series is a winner.  

The green meters (8025a, 8025b, 27/FM) were produced in great numbers for the US government, and are now showing up as surplus.  The new type 27s (with only the sticker on the back calling them 27/FM)  are also now being sold through surplus outlets.

While not as rugged as the 27-II and 28-II, these are rugged meters and are very reliable.  I have about 40-50 of these - and only three that are inoperative - one due to water submersion (cracked case.  an intact case is waterproof, provided the seals are in good condition and properly greased, as Dave explained in one of his blogs.) (another two or three were fixed with parts from these three)

Kiriakos, these have about 5 MOVs in the input, and I've seen meters with all 5 blown.  I changed them, and the meter worked and the cal was in spec.  Do you still have yours?  Maybe it's repairable.  I'll gladly send you parts and/or offer any help I can.

This is my favorite meter, probably because it's possible to buy them cheaply, they have millivolt and micro-ampere ranges in both AC and DC, and remain accurate despite a lot of abuse.  Some E-bay sellers sell these for 200-400 dollars, but I've seen new condition meters go for as low as 50, and good working models can be had for 20.  (all US dollars)

I use these for my "knock around, general purpose" use.  I have 87s that I use for electronic work, and the "big gun" 189-II (same as a 287) that I drag out on occasion.   Before i got a deal on the 189-II,  I bought a 189, and got a "fixer upper" 187 as well.   As Dave pointed out, the 287s are big and heavy.  The 189 and 187, although larger than the 87, is a bit smaller, and, more importantly, can be used without all of the button pushing that is involved with the 280 series.   

Some pictures of meters I had handy:





Note the meter at the lower right - it's a 27 meter with a 25 front case and buttons.  I found a new 25 case on E-bay and used it to fix a 27 with a very smashed front case.  I should have changed the bezel to a 25, but I didn't have one at the time.


EDITED - hopefully to improve clarity.  No fact changes were made, only re-stating and adding facts.

[Zyvek]

I have owned it for about 20 years now and it is still going strong. I has suffered some really hard knocks but works 100%.

I have a Fluke 27 that's about 20 years old, I took the case off and ran it thru the dishwasher and the thing looks brand new.

[Kibi]

Wow, Excavatoree, that was quite a write-up, and an interesting read. Thanks very much.
I certainly didn't know about the 8025a/b model numbers.
I have been looking around for an upper case for mine as the two top corners above the LCD have cracked. The performance of the meter is unaffected.
It seems very much like this meter was designated for US markets (government / civilian), quite how my one turned up in Zimbabwe, (I was born and grew up there), is anybody's guess.
I have seen quite a few ex-MOD (Ministry of Defence) green/brown 25's on Ebay.co.uk recently. They usually go for £30 or £40.
I also have a Fluke 79 III which has proved to be reliable. I bought that one new about 13 years ago.

[EEVblog]

I've had two yellow ones over the years, great meter.
I thought all the later versions you could buy were yellow as standard? as that's all they seemed to advertise up until the new Fluke 28-II came out.

Dave.

[zaoka]

I just bought Fluke 27FM over at eBay, brand new for $99.  They have more of them available.

I was thinking to buy Yokogawa TY720 but its to much money for me at this time...

[Excavatoree]

I just bought Fluke 27FM over at eBay, brand new for $99.  They have more of them available.

I was thinking to buy Yokogawa TY720 but its to much money for me at this time...

Just out of curiosity, if you don't mind, can you look at the lower picture in my reply #2 above, and tell me if your meter looks like the one on the bottom left or the bottom right?

[zaoka]

Neither, here is what it looks like:

http://cgi.ebay.com/NEW-Fluke-Model-27-FM-Multimeter_W0QQitemZ320650531707QQcategoryZ58300QQcmdZViewItemQQ_trksidZp5197.m7QQ_trkparmsZalgo%3DLVI%26itu%3DUCI%26otn%3D3%26po%3DLVI%26ps%3D63%26clkid%3D6922034333266134641


Do you know if this is oldest or latest model and is it True RMS?

[Excavatoree]

Neither, here is what it looks like:

http://cgi.ebay.com/NEW-Fluke-Model-27-FM-Multimeter_W0QQitemZ320650531707QQcategoryZ58300QQcmdZViewItemQQ_trksidZp5197.m7QQ_trkparmsZalgo%3DLVI%26itu%3DUCI%26otn%3D3%26po%3DLVI%26ps%3D63%26clkid%3D6922034333266134641


Do you know if this is oldest or latest model and is it True RMS?

Oh - the neat "contrasting decal" version.   I have one (surprise, surprise) but it wasn't handy for the picture.

These are the newest version.  This one is exactly the same as the latest "civilian" Fluke 27.   It's got the TI MSP430 processor instead of the "Fluke" branded part - I don't know who made them for Fluke - maybe it was TI.  I do know the pinout changed.

Unfortunately, these aren't True RMS.   (I just checked mine this weekend, to be sure)  The "rule of thumb"  is the designation on the front panel - if the LCD surround says "Fluke 27/FM" (bottom picture, lower left) it's true RMS, if it just says "Fluke 27" it is not.  The sticker on the back does say "27/FM" but these are different meters than those that were marked "27/FM" on the front.  The difference is the mainboard, which contains an IC marked "Fluke RMS."

The "Fluke 27/FM," to my knowledge, was only available in green, and sold to the US military.   Later, after Fluke changed to the yellow cases, I suppose they sold another batch to the US government and called these "27/FM" on a sticker on the back, but they are the same as the civilian model - no RMS.

I know of one E-bay seller who has purchased several of both types, and installs "true RMS" mainboards into the yellow cases - but he's nice enough to transfer the LCD mask, so the "rule of thumb" still applies.  However, the mainboards and LCD masks are interchangeable, and thus one could get one that has the "wrong" mask on it.  ("27/FM" mask on a non-True RMS meter, or vice versa.)

[zaoka]

Got mine today!

Very high-quality meter, readings the same as on Fluke 12.
For some reason when testing diodes I got different readings than with Fluke 12...

Bad sides is that its very slow when reading low-ohm resistors and slow autoranging for resistance and a lot slower than Fluke 12 when reading DC voltage.

I am getting Fluke 77IV next week and will do a short video clip comparing these 3.

[Excavatoree]

Good idea about the video - I'd like to see it.

Yes, these meters aren't as fast as the newer models.

I really like the 10/11/12 meters - did you know that these meters have something in common with the 25/27 type?  The 10 and 11 still have the circuitry for the functions of the 12.  I have a 10 with the front case drilled so I can push the "dummy buttons" that they use to access the ability to measure capacitance.

The only disadvantage is the LCD - very difficult to find and I see many that get black blobs.

These have 4000 count resolution, equal to the best 70 series meters (29,76, 79) and slightly better than the others. (70, 77, etc. had 3200 count)

I know the earlier meters were made in the US, I can't remember if the later ones were made in China, or if they all were made in the US.

[zaoka]

Just got Fluke 77IV, after quick testing in parallel mode an old FLUKE 12 outperforms 77IV and 27 in autoranging for DC as well as in MinMax mode.

If I use manual range it is very close battle

Will make video very soon!

[retiredcaps]

I really like the 10/11/12 meters - did you know that these meters have something in common with the 25/27 type?  The 10 and 11 still have the circuitry for the functions of the 12.  I have a 10 with the front case drilled so I can push the "dummy buttons" that they use to access the ability to measure capacitance.

These have 4000 count resolution, equal to the best 70 series meters (29,76, 79) and slightly better than the others. (70, 77, etc. had 3200 count)

I would love to see a picture of the modified Fluke 10 with the drilled case.

Also, since you have so many Flukes, is the Fluke 10/11/12 just as accurate in real life measurements versus a Fluke 87 wrt to DC voltage?  I see the specs are 0.9% for the Fluke 10/11/12 and 0.05% for a Fluke 87.

[Excavatoree]

First some pictures:

Front - with drilled holes


Close up of holes from front


Back Removed - Looks like an MOV and thermistor for protection.  There are no current fuses, because this meter doesn't measure current.


Board Removed


Plastic LCD Holder/Switch Holder Removed, Buttons removed to show holes from rear.
Note the back of the button assy has traces for all four buttons.


Button assy - memory and capacitance buttons are shaved.



As for accuracy, I don't have the equipment to be able to evaluate .05 percent vs .9 percent.   Mine reads right with my 87-V, and my 189-II (same as Fluke 287) but I don't think that's an iron-clad test.   It does indicate that perhaps it's a bit better than .9 percent, but that's good enough for many uses.

These don't have current capability, but they can be had much more cheaply, and they are compact.  They were made in the USA.  The only serious flaw is the LCD - you can see the black blobs in mine.   This LCD isn't available from Fluke, and it's hard to get a parts meter with no blobs.  I think I have one or two  completely clear one, and one that isn't as bad as this.

The capacitance function is also slower than the 87, but, again for 1/4 to 1/3 of the price (E-bay, used) it's not a bad choice, in my opinion, if you don't need the added features and accuracy.   Like Dave says, "Horses for courses." 

[retiredcaps]

First some pictures:

Thank for sharing not only these pics, but your Fluke staircase is one of my favourites.  Your guide on ebay is excellent too. 

I love the internal guts pictures as I'm trying to learn more about electronics and in particular multimeters.  Feel free to post more internal guts pictures of your Fluke collection.

As for accuracy, I don't have the equipment to be able to evaluate .05 percent vs .9 percent.   Mine reads right with my 87-V, and my 189-II (same as Fluke 287) but I don't think that's an iron-clad test.

Thanks for doing the quick comparison test.  I wonder if ThunderSqueak can share some of her thoughts about the Fluke 12 accuracy because she has a Fluke 12, 87, and 87-V?

[deth502]

Helo Kibi, and welcome!

I have two or three of the 25 model in the yellow case, and several more various versions of this meter. 27, 27/FM, 25 in green case, etc.)

I don't know much about the history, but I'll tell what I do know, and what I can theorize from the many examples I have seen.

The first generation meters:
These were the 8025a and 8025b.  They were dark greenish brown, or maybe it is brownish green.   These were only made for the US government.

Tbe only difference between the two is that the 8025a is missing the two center buttons. (Max/Min and Rel)  Oddly, the internal circuit boards are the same - an 8025B front case and rubber button assy will turn a 25/8025a into a 27/8025b.

The second generation meters:
These were the 25, 27 and the 27/FM.  The 25 is just like the 8025a, and the 27 is just like the 8025B.  (Only the 27 has the center two buttons - Max/Min and Rel.)  All were still in the brownish green case.  The 25 and 27 were sold to the civilian market.  The 27/FM was only sold to the military.  I'm not sure of the exact timing, which came first, if there was any overlap with the 8025's, etc.

The military model of the 27, the 27/FM is the only meter of this type with the "True RMS" feature.  There is actually an extra IC in the meter labeled "Fluke RMS."

The third generation meters:
These had yellow cases instead of the green.   Models were still the 25 and 27.  I'm not sure if there was any overlap of any of the green models with the yellow.  These yellow meters were sold to civilians for use in mines, and, as you note, were rated by the MHRA.  I've never seen a green one with that rating, but, all of these are the same, with the exception of the True RMS feature of the 27/FM.

There is "sort of" a 27/FM yellow meter, but "27/FM" appears only on a sticker on the back.  These latest government meters of this type look just like the civilian, yellow, 27 meters on the front.   Like all civilian 25s and 27s, these are NOT true rms.  (very confusing - to keep it straight, I don't call these 27/FMs, I only call the true RMS version a 27/FM.  That is, I go by the mainboard, not the sticker on the back)

Also, sometime in the "third generation," the Fluke logo was changed from the Fluke enclosed by the white rectangle with lines below to just the word FLUKE in a larger font.

These yellow meters were sold  until a year or so ago, when the 27-II and 28-II were introduced to replace them.  The 27-II is not true RMS, the 28-II is.

 Dave has a great review of the 28-II in which  he took one canyoning.  He had to work pretty hard to damage it, and it was repaired easily.  (broken LCD, broken inductor)  Looks like the new series is a winner. 

The green meters (8025a, 8025b, 27/FM) were produced in great numbers for the US government, and are now showing up as surplus.  The new type 27s (with only the sticker on the back calling them 27/FM)  are also now being sold through surplus outlets.

While not as rugged as the 27-II and 28-II, these are rugged meters and are very reliable.  I have about 40-50 of these - and only three that are inoperative - one due to water submersion (cracked case.  an intact case is waterproof, provided the seals are in good condition and properly greased, as Dave explained in one of his blogs.) (another two or three were fixed with parts from these three)

Kiriakos, these have about 5 MOVs in the input, and I've seen meters with all 5 blown.  I changed them, and the meter worked and the cal was in spec.  Do you still have yours?  Maybe it's repairable.  I'll gladly send you parts and/or offer any help I can.

This is my favorite meter, probably because it's possible to buy them cheaply, they have millivolt and micro-ampere ranges in both AC and DC, and remain accurate despite a lot of abuse.  Some E-bay sellers sell these for 200-400 dollars, but I've seen new condition meters go for as low as 50, and good working models can be had for 20.  (all US dollars)

I use these for my "knock around, general purpose" use.  I have 87s that I use for electronic work, and the "big gun" 189-II (same as a 287) that I drag out on occasion.   Before i got a deal on the 189-II,  I bought a 189, and got a "fixer upper" 187 as well.   As Dave pointed out, the 287s are big and heavy.  The 189 and 187, although larger than the 87, is a bit smaller, and, more importantly, can be used without all of the button pushing that is involved with the 280 series.   

Some pictures of meters I had handy:





Note the meter at the lower right - it's a 27 meter with a 25 front case and buttons.  I found a new 25 case on E-bay and used it to fix a 27 with a very smashed front case.  I should have changed the bezel to a 25, but I didn't have one at the time.


EDITED - hopefully to improve clarity.  No fact changes were made, only re-stating and adding facts.

well damn. thanks for pissing in my cheerois. 

just picked up an 8025b yesterday for $20. no leads, looked beat to shit, few dents/gouges in the case (nothing to bad, minor cosmetics) but it turned on, and hey, its a fluke!! for $20!!

came here and searched. well, found out its worth about....... $20.  so much for my big score.

anyhow, i got my first fluke anyway. for the record, the original govt acquisition price for these units was $392.53, so i guess i didnt do too bad....

thanks for the great write up and history lesson.

[KJDS]

I've got a pile of Fluke 25 is hard cases for sale. I was surprised just how good the accuracy of these is. If I get time I'll do a set of measurements.

[G4ZWI]

I've got a pile of Fluke 25 is hard cases for sale. I was surprised just how good the accuracy of these is. If I get time I'll do a set of measurements.

Hiya!!!   Thanks, I just purchased one!!!!
(Pick me a good ,un,  will you???    )

Cheers,  Fred

[trys]

I bought a Fluke 25 multimeter off ebay only last week.

I'm delighted with it. It came with leads, instruction booklet, and the hard case. It also had a calibration label on it, MOD calibrated last year - which is great.

I've checked it against a Voltage and Current reference (trusty old Micro Cal 130 from RS / Time Electronics) and it's spot on. It's a proper heavy lump of a thing, really substantial. It really is built like a brick 'sheet' house.

So far I've found the "hold" function really useful when going through a pile of resistors. It beeps when it gets the value and I can then let go of the probes, note the values, and move onto the next component. Simple.

I find it refreshingly intuitive to use. All AC measurements are on the right side of the rotary selector. All DC on the left side. Current inputs are on the left, volts and ohms on the right. No other clutter.

I love the analogue type bargraph display too for each reading. It give a visual display of change or value at a glance, which is very useful.

The fact that there is not much more I can say about it is good. It's a multimeter, robust, it's accurate and calibrated.

Trys