Bench Digital Multi Meter

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Any recommendations on a high count, accurate Bench DMM for under $350?

At the moment, I would like to measure very small ac signals and very small capacitors (pF).

Not remotely a requirement but it would be nice if I could measure inductance.

If you guys haven't already notice, I am trying to make a small lab for myself. The main uses will be for my EE studies and side projects.


Thanks,
Matt
 
I was looking for a bench DMM and started looking at LCRs and Meters like the HP34401a to cover the Gamut.

I wasn't prepared for the investment amount (even used) after a purchase from a reliable seller and maybe calibration.

I decided on a Handheld DMM but didn't want to go crazy on price because I still would like some solid benchtop meters as my foundation.

I was looking around at some that gave great value for the money like BK Precision(5390).

Chris (Anatech) was very helpful in keeping me in reality with considering the reliability and stability factor. (Thanks Chris) I was interested in the Flukes and was tempted to buy the 289 (I am not sure the difference between it and the 287 but the 289 is cheaper). Chris is a Fluke guy all the way but suggested I buy the newer Agilent U1242A (they also have a U1252A that competes with the Fluke 28X series). I bought the U1242A and I am totally pleased. Can't beat the value at $220.00 with the amount of functions and accuracy. You might look at these too.

If after looking, you are still considering the Fluke 28X, check Tequipment.net. They are reliable and have the best prices I have seen! (plus they aren't too far from Jack if you need to send in some muscle!)

I hope this helps!

Regards//Keith
 
Most DVMs won't measure small values of capacitors or inductors, nor will the frequency counter have enough digits to really thrill me. Even our Agilent bench meters at work, though really great meters, are limited in the cap value department. For home audio I still go for an older high performance bench meter, then use a separate bridge for component measurements. Used GR1650 bridges and nice HP frequency counters don't cost very much. Get a reciprocal counter if possible, as they're much faster at low (audio) frequencies.
 
I second Conrad -- if you need to measure small values a GenRad Digibridge or an old manual bridge are just the thing. From time to time,reference resistors, caps and inductors show up on the bay. The only problem with bridges is that they take up a lot of space. Even the Heath impedance bridges are pretty good (and with a little creativity you can add an independent frequency source.)

I am going to have to refresh the old Popular Electronics Reactance Measurement Test set with a PIC.

If you can measure time, distance and mass, you can measure anything.
 
Thanks for everyone's help!

I think a used GenRad Digibridge sound like a great solution. But I am confused on the the terminology. Are the following all the same thing or does the name indicate different features?

LRC Meter
LRC Bridge
Bridge
Digibridge

Does anyone know of a site that list all the different GenRad models and specs? Or a good resource for all LRC manufacturers? And has the company name always been GenRad? Wasn't it General Radio, then GenRad, and now something else?

The GR1650 looks huge and I believe it has an analog display. I would prefer a smaller model and a digital display.

Can all LCR meters measure quality? I have always wanted to be able to measure Q.

I see some state they can measure dissipation. Is that heat dissipation?

Thanks,
Matt
 
LCR, RLC, my goodness, you forgot CGRL! They are all more or less the same thing. C for capacitance, G for conductance, R for resistance and L for inductance. And Q for quality, D for dissipation factor. Order the letters any way you want. I work with an engineer with the initials "RLC". Always thought that was cool. There was an engineer at General Radio by the name of R. F. Field, but I digress. D=1/Q. If you know one, you know the other. General Radio Corp became GenRad, then was purchased by Teradyne. The test equipment rights were sold to Quadtech, then to IET (I think). Most of what you're interested in would be the earlier analog instruments because they're very accurate and built like a tank. The GR1650B is considered portable, as it runs on D cells, but it's still a big box by today's standards. My favorite manual bridge is the GR1608, but it's a large bench instrument and overkill for most people. There are various others, but they often require separate oscillators and detectors. The GR716C is a prime example of a very sensitive cap bridge, but it only does small value caps and requires you to supply the signal and detection. IMO, the 1650B is the best choice for the audio fanatic who's not a bridge fanatic. If you find a cheap Digibridge, they're also good, but usually overpriced. The base model is the 1657, and shouldn't cost over $150. The problem with most little digital meters today is they don't measure dissipation factor (1/Q). Without that, you don't know half the story. The B&K one does (did?) but they aren't all that cheap. You can also build a bridge quite easily- I posted a schematic a while back for one suited to large electrolytics, but it's easy to add whatever ranges you want. For audio frequencies it takes a couple precision pots, a couple rotary switches, and a few passive components. Don't get too hung up on "digital" as in this case the advantages are few and the pitfalls many.

General Radio Historical Pages

There's also a Yahoo group devoted to GR equipment.
 
I have the original Fluke 77 as well. It has been a work horse for the last 23 years and it is still going. I brought the Fluke 287 because Fluke 77 is not True RMS and I am not sure if it is still accurate after all these years.

I was considering an used bench meter vs Fluke 287 (close call) and chose 287 becase you really don't know if the used bench meter is still in spec. I have enough confidence on a new 287 to use it as the reference for the rest of the requipement.

When I checked my Fluke 77 against Fluke 287 it is about 3% off. A simple adjustment of R8 gets it back to the top shape again.

Fluke 287 eats battery much faster (on paper, hasn't run though first set of batteries yet) than Fluke 77. The battery in the Fluke 77 last longer than the watches that I had :eek: .

Howerver Fluke 287 is much better high frequency response. Fluke 77 not very useful when measuring against anything higher than 1 KHz.
 
OMG, I bought my 77 new when they first came out. Has it really been that many years? Now I feel old. Gather close around the campfire and I'll tell you about when gas was way under a buck a gallon, when you made paper copies with stuff called carbon paper, when the 'net wasn't even a twinkle in Al Gore's eye and you could do math by adding logs on two wooden sticks. Want me to teach you how to lay out PCBs with Bishop Graphics black tape and pads, then use the process camera? Fortunately, everybody still knows about valves!
 
Conrad Hoffman said:
Don't get too hung up on "digital" as in this case the advantages are few and the pitfalls many.

Conrad,

Can you elaborate on the advantages and pitfalls of the digital bridges vs analog?

What is the accuracy of the 1650? I found one site listing it as 1% but couldn't find another to confirm. Do you feel that is a comfortable amount?

How does the testing frequency make a difference? Some models go up to 1MHz. The inductors I am winding are going to be going in RF tanks tuned at ~1.7MHz.

Thanks,
Matt
 
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