Re: acmi error found? (LCR meters)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Gary,

I think your correct here. I just checked my notes where I measured Lp back
in MN. Granted the
coil has changed since, however, back then I measured within 3uH of a
calc'd inductance, so it's
close. I've been shopping for meters and it seems specs indicate the low as
0.1H. This is probably
where the "no gaurantee of accuracy" comes into play. The meter I used in
MN was also a Wavetek,
but I'm not sure what model. It was a standard LCR.

It seems to me that simply attaching a "known" measured higher inductance
to the primary should
make any inductance meter accurate (with a little subtraction). I haven't
tried this, but it
should bring the inductance into a known accuracy level (or is this too easy?).

Bart

Tesla list wrote:

> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Gary.Lau-at-compaq-dot-com>
>
> I can't agree that inexpensive LCR meters can't be used with primaries.  I
> have a Wavetek 27XT, in the neighborhood of $100.  My previous primary was
> 69uH, and it always gave reliable readings.  Today I decided to test it on
> my new high-inductance primary.  As a reference, I measured the resonant
> peak with a frequency counter.  The cap is a Maxwell with a printed value of
> .0196uF.  The Wavetek reads .0193uF.  If I use the printed C-value, the full
> primary calculates out to 225uH from the measured Fres.  The Wavetek reads
> 227uH, though there is about +/- 4uH of "noise" (I noted the highest and
> lowest values seen and averaged them).  If I tap in a few turns, L
> calculates out to  169uH, again with noise, and the meter reads 171uH.  I
> without reservation recommend this meter, as it's the only inexpensive one
> I've come across that can measure inductance, capacitance, and frequency,
> plus the usual V, I, & R.
>
> Regards, Gary Lau
> Waltham, MA USA
>
> >Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
> >
> >An LCR meter is great for the secondary, caps, and all kinds of other stuff
> >but they are pretty bad for the primary inductance.  The inductance is so
> >low that LCR meters are pretty bad.  I used a scope, frequency generator,
> >frequency counter, and the HP 34401a to detect the absolute peak in my
> >measurements.  Yips!  that's about $3000 bucks worth of toys!!  But get the
> >LCR meter!  They are invaluable and I use mine all the time!  The B&K 878
> >or 875 are fine toys!  I have an old Elnico but I use the B&K's at work.
> >Stanford makes a super ultra nice one but it is an extra grand :-(.
> >
> >Cheers, Terry