[Elecraft] Re: LC Meter

Cortland Richmond cortlandka5s at netscape.net
Sat Nov 27 09:24:43 EST 2004


Try this, Chas: With the leads on the part being tested, take a reading. 
Then, without moving the leads, short them and read leads-only 
inductance. Subtracting lead inductance from the value previously read 
will very often get you quite close to the REAL value. Some meters - and 
that Elenco should be one - have an offset function, allowing lead 
parasitics to be removed automatically.  My B&K does.

You say your MFJ 259B is not accurate. It should be. In fact, at RF it 
should be closer than the Elenco, which uses audio and misses the effect 
of turn to turn parasitic capacitance. BTW, the 259B is capable of 
reading inductance directly, rather than resorting to the grid-dip 
option; its frequency calibration is good enough that detecting 
resonance can be more accurate. though. To get that accuracy, you will 
need resonating capacitors whose value are rather precisely known . Have 
you tried, instead of dipping, detecting series resonance directly?

Cortland
KA5S

>From: Charles Greene <W1CG at QSL.NET>
>
>Elenco LCR-1810.  It has a 200 uH sacle as the lowest scale, but it  does 
>not read correctly and is off by a factor of 2:1 at low values of uH.   I 
>need to read uH in the range of 2 TO 200 uH (HF inductors).  The only thing 
>I have other than the Elenco is a MFJ 259B with the grid dip option which 
>is a pain to use and not that accurate either.
>


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