[ARC5] LCR meter - question in support of mil surplus restoration....

[Roy Morgan]

On Nov 21, 2013, at 9:43 PM, John Hutchins <jphutch60bj at gmail.com> wrote:

> Group -
> 
> I have a question -  Al the LC|LCR meters ... are > 100.00 but oll onl measure down to 20uH  3 digit precession or 200UH 5 digit precession….  one ...on Ebay ... goes to : 0.001uH
> Any thoughts ?

Yes. 
Here are my thoughts:

 - NO one doing ham work *needs* three digit precision, let alone 5 digit precision (except in frequency setting)

 - The results you get from measuring an inductor to three digits would almost certainly change by at least one digit in the second place and who knows what in the third place, simply by making the leads a bit longer or shorter when testing.

 - 20 micro henries is not a lot of Henry.  RF coils in transmitters might be of this magnitude.  It may be far more realistic and meaningful to put a test coil into a real circuit and measure it’s resonant frequency with a good grid dip meter.

 - The meter that can measure down to 0.001 micro henry is almost certainly fooling both itself and you with such numbers. One inch of number 14 wire has an inductance of 0.016 micro henry (see: http://www.consultrsr.com/resources/eis/induct5.htm )

 - There is an important difference between precision and accuracy.  Do not confuse the two.  How space scientists and engineers can hurl a one-ton thing off to Mars and have it arrive a year later at JUST the right place and velocity boggles my mind.  I suspect they have developed an unprecedented amount of both precision and accuracy.  (And considerable patience.)

Side note:
The first day of Hanukkah falls on Thanksgiving this year.  
It will not do so again for some seventy eight thousand years.  Who knew?  (*)

Roy

Roy Morgan
RoyMorgan at alum.mit.edu
K1LKY Since 1958

*  Jonathan Mizrahi, a Jewish-American quantum physicist at Sandia National Laboratories in Albuquerque tells us this.
Some learned people tell me that I, and you, might be back here for that event.  Email me off list for more.
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