New Fluke Multimeter recommendation?

[Axtman]

I am in the market for a new multimeter. I want to buy a very good quality Fluke or equal. I would like an auto-ranging model with capabilities of 700 volts or more DC. Of course I want the usual Ohms, VAC, frequency, amperage, etc. But I also want one that tests large value capacitors.

What Fluke model do you recommend?

[Enzo]

A couple of thoughts. What will you use a frequency meter for? I have a freq meter on my bench, and the ONLY thing I ever use it for is to check the speed of tape decks.

And cap testers - hand meters like that only measure the capacitance value of the caps, it can't test for leakage, nor can it remotely test them for leakage at working voltage. For instance, a filter cap in a tube amp might have to work with 450-500 volts across it. A cap that tests fine at the volt or two from a hand meter might leak like a screen door at anything over 50v. Your meter would never know that. Some meters will also measure ESR of caps. I myself never seem to need to know that, but some guys like it. I don;t know that the FLuke line includes ESR on their cap scales.

Accuracy. I think most of them these days come in at 1% or less on the readings. And while you can find the 5 digit meters, the plain old 3.5 digit meters are fine for amp use. Trust me, you don;t need to know whether your B+ is 458v or 458.27v. As you go from basic accuracy to tiny fractional percentages, the price starts to soar. The difference betwen .5% and .2% is not worth paying extra for. We are not making laboratory measurements. A 2200uf cap doesn't usually go bad by changing to 1500uf. it usually fails by shorting, opening, getting leaky at voltage.

[Gtr_tech]

ESR readings are useful if you do any vintage home audio amps. The cap coupled output types you need to keep an eye on. The coupling cap at the output can degrade the high freq response if it goes high ESR.

For the OP: I haven't kept up with Fluke's revisions over the years....last I knew they were putting digits in front of the original model #s (the 77 became the 177, etc). I use a 79 daily and it has freq and the cap scale. I haven't used the cap scale since I got a dedicated Sencore cap checker. The freq counter can be handy once in a great while, but it only covers the audio band to 20k. One thing to check for is a meter that has min/max function. That can track lowest and highest readings so intermittant problems can be tracked down without hawkeyeing the display.

[techineer]

Some meters will also measure ESR of caps. I myself never seem to need to know that, but some guys like it. I don;t know that the FLuke line includes ESR on their cap scales.

ESR of capacitors is an important factor in switching-type power supplies that operate at tens or hundreds of kilohertz. At these frequencies, ESR becomes a loss that can prevent the supply from starting up or running properly, even though the cap 'tests' good. And most switching power supplies have quite a few electrolytic caps in them, so substitution is not a practical method of troubleshooting. However, it's not usually a major issue in audio servicing except for the high efficiency switching power amps like Crown and QSC.

See the page at Home Page ESR METERS, Capacitor Wizard, Doug Jones. The operating manual for the Capacitor Wizard is there. It explains what ESR is and why it is useful to test for it. (This is the site of the fellow who invented the ESR meter.)

I do find the ESR meter to be useful at other things, though. It's basically a low-resistance scale ohmmeter at high frequency AC. Good for checking low value resistors and spotting shorted semiconductor junctions.

As for DMM choices, I've tried quite a few. I have an old Fluke 77 that I've had for 25 years or so, and it's still my favorite. However, it (and many others) have one major drawback that is important in audio servicing - Frequency Response. Most DMMs roll off above a couple of hundred Hertz. Many amps require (at least for factory tests) that you take measurements at 20KHz. The Fluke 77 is useless at this. SO CHECK THE FREQUENCY SPEC for AC voltage measurement. For these measurements, I'm using a couple of relatively inexpensive Tenma true RMS meters that cover the full range.

A good low millivolt range is also useful for setting bias currents on output stages.

PROTECTION! Flukes are good at protecting themselves against the OOPS! moments... such as forgetting to switch from ohmmeter to volts before you measure the plate voltage on the output tubes.....

[Enzo]

I understand the importance of ESR in circuits, fellas, I just find it a lot faster to sub a part than take it out and characterise it. Same reason I don;t use a tube tester.


And i sure will agree that the FLuke handles connecting the ohms scale to a live circuit more often than I'd care to admit. It just shows a funny display or a negative resistance and shrugs it off. I have an HP bench meter that has a 32ma fuse in the input. Touch it to voltage on ohms and poof. Those little fuses are not cheap.