Bench Digital Multi Meter - Page 2

TheDriver · 22nd July 2008, 05:46 AM

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

Conrad Hoffman · 22nd July 2008, 01:04 PM

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.

Zero Cool · 22nd July 2008, 01:15 PM

I have a Fluke 189 and it has been the best purchase i have ever made for my shop!! My only complaint is that it is batteries only. does not run on AC power. and no adapters is available for it. But i would buy it again in a heartbeat!

Zc

jackinnj · 22nd July 2008, 01:18 PM

Quote:

Originally posted by Zero Cool
My only complaint is that it is batteries only. does not run on AC power. and no adapters is available for it.
Zc

Go to Radio Shack, get a 9V battery connector and a 9V wall-wart.

slam · 22nd July 2008, 02:07 PM

Circuit Specialists has Fluke 287 on sale for $359, but best I have seen. I got mind there and was pretty happy with it.

http://www.circuitspecialists.com/prod.itml/icOid/9460

One thing I wish it had was the AC power adaptor. One nice thing about bench multimeters is that you can plug it in and leave it on all day long.

jackinnj · 22nd July 2008, 02:52 PM

My Fluke reminds itself to take a nap when it is accidentally left on.

But I have to purchase batteries at Costco !

Jack

Conrad Hoffman · 22nd July 2008, 05:47 PM

Though I have a variety of meters, the one that sits on the corner of the bench and gets used the most is an old Fluke 77. For all the use, plus me forgetting to turn it off, the batteries seem to last 3-5 years. I can't remember the last time I changed it. Low features = low power consumption!

slam · 22nd July 2008, 09:36 PM

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

.

Howerver Fluke 287 is much better high frequency response. Fluke 77 not very useful when measuring against anything higher than 1 KHz.

Conrad Hoffman · 23rd July 2008, 03:33 AM

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!

TheDriver · 23rd July 2008, 05:10 PM

Quote:

Originally posted by Conrad Hoffman
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

22nd July 2008, 01:04 PM	#12
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	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. __________________ What's in your junk box?

22nd July 2008, 05:47 PM	#17
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	Though I have a variety of meters, the one that sits on the corner of the bench and gets used the most is an old Fluke 77. For all the use, plus me forgetting to turn it off, the batteries seem to last 3-5 years. I can't remember the last time I changed it. Low features = low power consumption! __________________ What's in your junk box?

23rd July 2008, 03:33 AM	#19
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	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! __________________ What's in your junk box?

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22nd July 2008, 05:46 AM	#11
TheDriver diyAudio Member Join Date: Jul 2004 Location: Iowa City, IA	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

22nd July 2008, 01:15 PM	#13
Zero Cool diyAudio Member Join Date: Sep 2004 Location: MN	I have a Fluke 189 and it has been the best purchase i have ever made for my shop!! My only complaint is that it is batteries only. does not run on AC power. and no adapters is available for it. But i would buy it again in a heartbeat! Zc

22nd July 2008, 02:07 PM	#15
slam diyAudio Member Join Date: Jan 2005 Location: CA	Circuit Specialists has Fluke 287 on sale for $359, but best I have seen. I got mind there and was pretty happy with it. http://www.circuitspecialists.com/prod.itml/icOid/9460 One thing I wish it had was the AC power adaptor. One nice thing about bench multimeters is that you can plug it in and leave it on all day long.

22nd July 2008, 02:52 PM	#16
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	My Fluke reminds itself to take a nap when it is accidentally left on. But I have to purchase batteries at Costco ! Jack

22nd July 2008, 09:36 PM	#18
slam diyAudio Member Join Date: Jan 2005 Location: CA	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 . Howerver Fluke 287 is much better high frequency response. Fluke 77 not very useful when measuring against anything higher than 1 KHz.

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