Get a Fluke DMM

[john65b]

As long as we are on the topic of meters, is there a Fluke meter that can measure Caps and Inductors? This would be really what I would need....volts/resistance/amps/capacitance/inductance meter is all I really need - maybe frequency?

Anywho, apexjr has these no-name meters that do uF - F and uH - H (pretty good range too) for $50 and I have been thinking about getting one...I have enough old scrap inductors laying around...would love to be able to re-use some of them if I could find out what their value was...

I also have a Textronix 5110 (?) I got off ebay a year or so ago and still haven't used it...need a tutorial of sort...want to check some preamp power supplies...all the EE's I work with don't have a clue on how to use it...

[aymanme]

I do not think you will find inductance on any of the handheld fluke (multimeters). I use the 87 and 77 and find them perfect for most everything. Some of the benchtop are faster or have higher precision but you have to be more careful, since they run on mains, they can pick up noise if you are measuring small currents or voltages.

To measure inductance, there are a couple of choices. You can get another meter to do it (esp if you do not need high accuracy), or a fluke lcr like a PM 6303 or lastly, there are many circuits posted around of how to build an LC meter from a PIC/AVR micro.

[anatech]

Hi John,
Build an LC circuit and oscillator to figure out your inductors. Buy some precision capacitors to use in your oscillator. A Fluke 87 can then be checked with the caps (as your "standard") and read the resulting oscillation frequency. After that it's only math. Cheap and more accurate than cheaper inductance meters.

I use an HP 4263A LCR meter. Expensive, but worth every penny if you need something this accurate.

-Chris

[dangus]

One thing to watch for with buying used Fluke meters is the condition of the LCD. Sometimes a few segments go out: that can often be fixed by swapping the "zebra" strip (or whatever it's called) end-for-end. But if the displays go dark, that can cost some money to replace. I bought my Fluke 77 around the same time as two coworkers did, and both their displays went bad within 5 years. Inexplicably, mine is still legible after about 20 years.

When it comes to bench meters, consider an LED meter instead.

Another thing with some Fluke 77's is that the 10 amp range was NOT fused, so you could get into trouble if you lost track of how the test leads were connected.

Bear in mind that a couple of generations of electronic techs and designers got by just fine with analog meters.

As for L and C:

AADE had a couple of versions of an LC meter published in Radio-Electronics (or whatever it was called at the time); the first used logic chips in a clever way, the next a PIC (and very little else). I don't see the plans on AADE's website any more. $100 for a kit ain't too bad: http://www.aade.com/lcmeter.htm
There's links to reviews of it.

Maybe the more sensible approach is to use a sound card with analysis software; I know the IMP/MLS would measure complex impedances.

[dangus]

A little more searching found an article on building an L/C meter:
http://www.geocities.com/ttarsorg/co...lc-meter-2.pdf
http://www.antrak.org.tr/gazete/111998/barbar.htm
It's the AADE L/C meter, the second version that was published in the June 1996 "Electronics Now".

[anatech]

Hi Dangus,
I repaired many Fluke meters. Most of the time you only need to gently clean the zebra strip with 99% alcohol and reinstall it. Clean the PCB and display contacts as well. Do not touch any of these surfaces. The only displays I ever replaced were broken ones. I did have to replace some zebra strips though. They should be cheap from Fluke, so are the displays.

-Chris

[mpmarino]

Originally posted by mpmarino
Chris,

Sitting in my Boss' office is a ~1 yr old fluke 88 that reads CAL on the display. I currently have a 87 and 88 (both really beat but beautiful on the inside) but wouldn't mind adding another 88 to the mix. Do you think I could get it going without spending anything??

.....................
Sorry for a bit O.T.

Originally posted by anatech
Hi mpmarino,
I'm not familiar with the 88, but I do now that the later Fluke meters were closed case calibration (yahoo!) because the proximity of the case affected the higher frequency AC cal. I had built a jig for 87's for that reason. Not perfect, but much closer than an open optimization. I sent all my jigs to the Transcat Rochester lab when I left. So some $$ is required as they need to access it with their cal program. What happened to it? Also, it should be withing the warranty period (1 year).

.......................................

-Chris

Well, whadya know! It's actually an 87V and it still has the plastic protective cover on the display AND it's in my possession. I gave Fluke a call and it has a conditional lifetime warranty. Yippeee! As long as it hasn't been overvoltaged (doubt it, the most we work in is 240v) and hasn't been physically abused (can't see that) they will fix it for free. Yipeee!



edit: I have the cal procedure but not the equip to do it - I'll let them do it.

[anatech]

Hi mpmarino,
You are one lucky fellow. That is one very nice meter.

Remember me if you fine another.

Actually, I am very happy for your good fortune. It may need a fuse.

-Chris

[dangus]

anatech:
On the "dark" LCDs, it wasn't just a segment or two that were out (which is what I've fixed by doing the strip flip or clean); the whole display gradually lost contrast, and looked dark even when the meter was switched off.

[anatech]

Hi Dangus,
That's interesting. Early meters did that as I've mentioned. The only other thing I can think of is that the meter display was exposed to full sun often. Nothing else comes to mind here.

At any rate, a new display LCD was not very expensive. Replace the zebra strips at the same time. Either that or replace the entire meter. The display is less expensive to do.

-Chris