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LCR-Meter Question

A

Anonymous

Guest
Hi all,
How are your experiences with an LCR-Meter. Which is a good LCR-Meter (hand-held) for measuring search coils? What kind of LCR-Meter I should look for and how much should it cost?
Should it show/measure the "Q" factor as well? How about the accuracy, frequency range, inductor range?
Can someone give me a recommendation?
Chris
 
Order a few inductors in the following approximate values: 100uH, 300uh, 500uH and 1000uH/1mH. Test them on your LCR meter and note if they are high or low on the low L scale. Anything you measure should be relatively the same as the variance measured above.
Heathkit made a low cost RCL bridge model IB-5281 that shows up on e-bay from time to time. I have one and it is pretty good for obtaining pretty consistent measurements on coils that I wind in the 250uH to 500uH range. Inexpensive LCR digital readout meters can be had for between $40 to $60.
The Tektronics model 130 is an old tube LC meter that measures up to 300pf and 300uH. Once calibrated, it too is pretty consistent. This shows up on e-bay from time to time.
What type of PI machine are you making the coils for? What is your primary target, coins or jewlery?
bbsailor
 
Hi Chris,
I personally use the BK 878 LCR meter I picked up off Ebay for a good price. It seems to work quite well. I paid a little over $100 for mine, but a new one is about $250 or so. I also have a lower priced Wavetek that seems to be about as accurate.
Now, I do not really worry about the Q factor since I am just building PI coils. I just worry about the number of turns and coil and wire size.
I will generally just use a website to determine the number of turns when I change coil size. It seems to be quite accurate. I will check the coils with my LCR meter just to make sure I didn't screw up, though.
That site is noted below. Just use about 0.25 inch for the coil length and plug in the other numbers to get the coil inductance. Use the .1% calculation. As an example, if you plug in 21 turns, 11 inch diameter and 0.25 inch length you should get 361.433 or so uh. An actual coil will be reasonably close, depending upon the wire used. If the actual inductance is off a little because of the wire insulation, you adjust the length a little to correct. Generally, something between .22 and .30 for the length works very well when going from magnet wire to hook up wire. I will just use the .25 inch and see how it works out.
The nice thing about the site is you can use millimeters or centimeters instead of inches for your measurements if you desire.
Reg
 
I have had very good results with the Extech model 380193 LCR Meter, especially for low-Q coils. The Extech seems to have a particularly wide range of primary (like inductance) and secondary (like resistance or Q) parameter values.
I had a BK Precision 875B, but wasn't happy with it. The Extech was the replacement.
 
Hi Reg,
thanks for your input & the link. I tried the calculator from the web. The calculator is pretty accurate. The calculation from the web site calculated 315uH for my coil. My own measurement with the scope gave me the value 312uH. That's pretty close.
Chris
 
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