Questions for those with LCR Meters

[belwar]

Hi Guys (and Gals)

Bought myself an LCR meter last night (a BK Precision 878) and Im wondering something. Every LCR meter I saw came with an RS232 port (standard comm port) and each one says in the brochure that It will "Link to a computer with RS-232 cable and Software (Not included)" So my question is this.. What software can you connect an LCR meter to? Has anyone connected thier meter? I'm a techie so im always looking at new ways to incorporate my computer.

Also, I've never tested for L (inductance) before, and as im reading this meter tests for L at different frequencies. Which of those frequencies is standard to use? or will it give me roughly the same reading at each frequency?

belwar

[Chadheckler1]

I just recently got one myself (Extech) and mine has two freqs, 120hz and 1khz I think... the Inductance will be different at every frquency. I record both for every pickup in case I want to reference it later, but I think that the standard one that you see for pickups is 120...?

[salvarsan]

LCR meter manufacturors are essentially chislers.

Both ExTech and B&K want $70+ for a glorified $10 cable
and some dubious software.

Once you have the cable, you can use a modem program
to receive data from the meter. Either TeraTerm on Windows
or Minicom on Linux will work fine.

Baud rates are usually 1200 or 9600. While most sane corporations
use 8 data bits, 1 stop bit, and no parity, meter bit parity is usually
set ODD as a soft-headed short-sighted attempt at obfuscation.

If you want serial link command codes, Extech will provide them
to you so you can write your own meter data acquisition application.

B&K never answered my requests. You may have better luck.

Excoriatingly,
-drh

[NightWinder]

Program

The Extech Comes with the cable and the program...Not sure if it matters where you order it from, but this is my second one and it came with the 1.3 version and the cable

[belwar]

salvarsan,

Thanks for the info. I didnt even consider hooking it up to a terminal program. Takes me back to the day or 2400 baud modem BBS's. What kind of information does it send to screen? I'm trying to figure out what the advantage would be. Like if you are reading L, does it spit out the current L reading every 1/10 of a second or something?

Thanks

[Magnut]

Basicly it's just an extension of the screen on the meter. What ever shows on the meter shows on your comp. It allows you to record this info and save on your hard drive. It can take a of sample all that you connect to it and record a list. From this you can get an average, set high / low tolerences and keep track.

[Joe Gwinn]

Hi Guys (and Gals)

Bought myself an LCR meter last night (a BK Precision 878) and Im wondering something. Every LCR meter I saw came with an RS232 port (standard comm port) and each one says in the brochure that It will "Link to a computer with RS-232 cable and Software (Not included)" So my question is this.. What software can you connect an LCR meter to? Has anyone connected thier meter? I'm a techie so im always looking at new ways to incorporate my computer.

Also, I've never tested for L (inductance) before, and as im reading this meter tests for L at different frequencies. Which of those frequencies is standard to use? or will it give me roughly the same reading at each frequency?

Never mind the software for now. First verify that the B+K 878 LCR meter can work with low-Q inductors like pickups.

The test is a 2-henry inductor in series with a 50K pot: As you vary the series resistance, how much does the claimed inductance vary? If it's more than a few percent, take the meter back.

My first LCR meter was a B+K 875. It was not a success.

[David Schwab]

Never mind the software for now. First verify that the B+K 878 LCR meter can work with low-Q inductors like pickups.

The test is a 2-henry inductor in series with a 50K pot: As you vary the series resistance, how much does the claimed inductance vary? If it's more than a few percent, take the meter back.

My first LCR meter was a B+K 875. It was not a success.

I was thinking the same thing... I don't have an LCR meter yet, but I remember talk here that the Extech is the only one that works with pickups.

[salvarsan]

What kind of information does it send to screen? I'm trying to figure out what the advantage would be. Like if you are reading L, does it spit out the current L reading every 1/10 of a second or something?

1) call me Dan.

2) The Extech spits out a text string formatted according to your measurement
selections. If you selected L with resistance and capacitance as secondary
measurements, you get all three every 2-3 seconds. The firmware may have changed in the last five years.

I've appended the Extech 380193 command protocol document, a laconic 78k PDF.

-drh

[belwar]

1) call me Dan.

2) The Extech spits out a text string formatted according to your measurement
selections. If you selected L with resistance and capacitance as secondary
measurements, you get all three every 2-3 seconds. The firmware may have changed in the last five years.

I've appended the Extech 380193 command protocol document, a laconic 78k PDF.

-drh

Thanks Dan!

I think based on your guys feedback I'm just going to return this unit to Frys and get one that people say DOES work. Now I just have to find it.

Does anyone know if the Extech does Q calculations?

[belwar]

Cheapest price I found

Well im going to pull the trigger on the extech. I spend some time searching and found this place "Allied Electronics" selling it for $174. I was linked to them right from Extechs site so they must be legit.

http://www.alliedelec.com/Search/Sea...d=11D0088164CE

belwar

[salvarsan]

Does anyone know if the Extech does Q calculations?

You get them for free with the Extech, same as with the B&K 878A.

Before you pull the trigger on an Extech, see if the B&K misbehaves with
high series resistance as Joe Gwinn wisely suggests.

Your newer 878A may work just fine, whereas his earlier 875 was
unsuited for guitar pickups.

What you don't get with the B&K is AC resistance as a secondary
measurement.

-drh

[soundmasterg]

I was thinking the same thing... I don't have an LCR meter yet, but I remember talk here that the Extech is the only one that works with pickups.

Yah, theres a reason why most everyone here and places like Rickenbacker use it. It works great! Too bad there is nothing out there for a reasonable price that tests accurately at higher frequencies than 1kHZ. Thats pretty low on the guitar notes.....

I suppose you can compare the 120 HZ to the 1kHZ and see a trend, but it would be better with higher freqs I'd guess....

Greg

[belwar]

Yah, theres a reason why most everyone here and places like Rickenbacker use it. It works great! Too bad there is nothing out there for a reasonable price that tests accurately at higher frequencies than 1kHZ. Thats pretty low on the guitar notes.....

I suppose you can compare the 120 HZ to the 1kHZ and see a trend, but it would be better with higher freqs I'd guess....

Greg

So a function of how well they work is thier accuracy at the higher frequencies? There is a BK one called the 879 which goes higher than 1khz. It goes upto 10khz. It's reasonable at $250 street price. Is the accuracy published or do you simply have to try it?

[jrfrond]

I was thinking the same thing... I don't have an LCR meter yet, but I remember talk here that the Extech is the only one that works with pickups.

My WaveTek (now Amprobe) LCR55 works with pickups, but there is no RS-232 interface for data capture, just pen and paper!