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Author Topic: $200 LCR meter. Any good  (Read 16845 times)
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K6JEK
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RF in the shack


« on: August 30, 2007, 12:54:15 PM »

I need a pretty darned accurate LCR meter, better than the Peak LCR40 hand held I use all the time.   I notice on eBay a hand held sold by a variety of different people with different brands.   Prices range from $155 - $200.   It claims accuracy to .3%, good enough for what I want to do.   Here's just one of the eBay item numbers:  190146951153   

Can this thing be any good?

Are there alternatives with names like Fluke or HP that can be had for close to that price?   I would pay a 50% premium for something not made in China.   I know.  I'm dreaming.

Jon



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w5dud
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« Reply #1 on: August 30, 2007, 01:43:34 PM »

Hello look for a Sencore Z-Meter, I think it is a Model LZ-53, have owned several very accurret, Dudley/W5DUD
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n2bc
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« Reply #2 on: August 30, 2007, 04:09:49 PM »

Did you look at the AADE unit??

http://www.aade.com/lcmeter.htm

$100 kit, $130 assembled.   Accuracy comparison pointer on the above page.  Very handy for the L/C component in the RF range.

73, Bill   N2BC
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K6JEK
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RF in the shack


« Reply #3 on: August 30, 2007, 04:46:34 PM »

Thanks for the tips.  The AADE is about as accurate as the Peak that I have so that wouldn't be an improvement.  The Sencore looks like a very interesting piece of equipment.  The new model, the LC103 costs over a grand but the older 53 might great.   It looks like a very handy tool to have. 

I appreciate the help

Jon
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #4 on: August 31, 2007, 05:32:06 PM »

Dunno what the accuracy actually is, but perhaps an old GenRad Impedance bridge will give you the best results, since you can pump in signals of freq other than a noiminal 1kHz. ?


          _-_-bear
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_-_- bear WB2GCR                   http://www.bearlabs.com
atulbhagwat
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« Reply #5 on: December 14, 2008, 11:04:58 PM »

Pl checkin this instrument at 270 USD + Shipping.
This is a professional instrument at cost of handheld instrument;
Pl Check at
http://sites.google.com/site/knohowlcrmeter/
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WD5JKO
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WD5JKO


« Reply #6 on: December 15, 2008, 08:25:38 AM »

Jon,

   Measuring caps and inductors at the frequency of use is very important. A .01 uf cap with 2-3 inches of leads will go through series resonance around 7-10 Mhz. Above that SR frequency these dudes look like inductors! So take your fancy LCR meter that is .0001% accurate at 1 khz test frequency, and you will learn a hard lesson that at HF and above those test results are virtually useless.

   Bear touched upon using an old Gen-Rad bridge where you can input the test frequency from an external source. He hit the nail on the head. I use the Autek RF1 analyst which calculates C, R, and L at whatever frequency you want. The VA1 model would be better since it gets the sign of X right.

Here is what Autek says about this, "L and C are measured at the RF frequency of interest, not at 1 KHz or 100 KHz as on other meters. So the effects of stray capacitance, toroid parameters, and other frequency-dependent factors are taken into account. The RF1 can even measure the inductance of less than 1/2" (1 cm) of straight wire!"

Accuracy depends on the setup where every inch of wire adds Xl which subtracts from Xc. In order to measure with accuracy at HF and above you need a VERY expensive gizmo. Even more important, the testing setup is critical, and that must be defined based upon what you are going to test. Any test lead from the meter will need to be calibrated out with an OPEN, SHORT, and terminated load to cancel out the effects of the test cable.

With the Autek RF1 you will be lucky to get better than +/- 10% accuracy. That said it will be far better than that fancy digital LCR meter which uses a 1 khz test frequency yet boasts 1% accuracy.

With the RF1 I simply take whatever I test and with a minimum of leads I hold up to the SO-239 connector. This feature works very well for evaluating RF bypass capacitors over the HF range.

my 2 cents,
Jim
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w3jn
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« Reply #7 on: December 15, 2008, 02:28:03 PM »

The HP 4261A digital R-L-C bridge is fantastic.  They seem to sell for $2-300 on eBay; I scored one for about $50 at a hamfest some years ago.

A bridge is far superior to those handheld digital LC meters that use the element as part of an oscillator, then calculate the component value based upon the oscillation frequency.  They are subject to huge error if the capacitor is leaky or has substantial ESR - or the inductor has substantial resistance in the windings.

The 4261A will measure ESR and equivalent parallel resistance (ie leakage).  Will measure at 60 hz or 1KHz as I recall.  Why buy hammy hambone grade when you can get lab grade for just a little more?

BTW ".3% accuracy" is a joke.  Inherent stray inducance and capactitance in the component and test leads make this spec extremely suspect.
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WD5JKO
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WD5JKO


« Reply #8 on: December 15, 2008, 06:15:49 PM »



John,

   I am sure the HP 4261 is a fine instrument when used as designed. You missed the point that at RF you MUST make measurements at the frequency where the component will function and you must make the measurement with a lead length that approaches zero length. The best instrument in the world with a 1 khz test reference will be useless looking at your bypass capacitor to see if it is any good on 10 meters.

   Other HP instruments I've used that will do this is the 3577a 0-200 Mhz network analyzer with tracking generator along with the optional s - parameter box. This thing is great, big, heavy, and I'm sure expensive as hell.

For about 100 bucks (maybe more) the Autek RF1 or VA1 will do what most of us need. Nothing wrong with "Hammy" test equipment so long as the user understands the limitations of the device. Conversely using an expensive HP at 1 Khz looking at RF components is not going to accomplish much.

Consider what I've said. Even the 1 KHZ units are poor for looking at 50-60 Hz chokes and transformers.

Regards,
Jim
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w3jn
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« Reply #9 on: December 15, 2008, 07:29:12 PM »

Indeed you are correct to obtain 100% characteristics of the device under test at RF.  However, the 4261A allows you to null out test lead capacitance and/or inductance.  I'm not saying that this is the be-all/end-all LCR tester - obviously there are better units costing upwards of $10K used.

My point here - which I think you might have missed - is it's light years ahead of those hammy hambone handheld testers for about the same price.
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WD5JKO
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WD5JKO


« Reply #10 on: December 15, 2008, 09:36:23 PM »


John,

   The Hammy Hambone meter (Autek RF-1) can be used as a frequency source, SWR meter (based upon it's own VFO), a capacitance meter, and inductance meter, and the part I like the most is a Z meter. Recall that a Z meter measures the square root of (X^2 + R^2). These features are extremely useful to a ham that is clue-full as to what those terms mean.

   Sure I'd like to have that HP box you mentioned. That said it would only do a small portion of what I need when the Autek is IMHO a huge bang for the buck. If I was designing an audio phase shifter for a SSB phasing rig, that HP box would be what I'd need. On the other hand if I wanted to make a 9 Mhz phase shifter for the same rig, I'd use the Autek. The Autek is not appreciated because it is in the shadow of a lot of the MFJ stuff that is more limited in capability.

Jim
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Steve - WB3HUZ
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« Reply #11 on: December 15, 2008, 09:52:39 PM »

Jim, I think you and John are in agreement. He's not talking about the Autek, since it is a multifunction antenna analyzer. His comments are directed towards handheld LCR meters. Two different animals.
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w3jn
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« Reply #12 on: December 16, 2008, 05:48:13 PM »

Indeed, Steve.  I am focusing on those (largely Chinese) handheld digital L-C meters.

There are all manner of test instruments in my shack that I could use to figure out capacitance or inductance, but none go by the name "digital R-L-C bridge"  Grin
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