[600MRG] inductor measurements

[Rudy Severns]

Frank is right on the mark.  

 

You have to be careful when measuring inductor characteristics if you want
accurate results.  If you have a Q-meter it's very instructive to mount the
coil in place, measure the Q, and then place a sheet of copper board or
aluminum at various distances around the coil.  When you place a conducting
sheet close to the coil the Q-meter reading will drop dramatically but
that's mostly detuning from resonance.  You have to re-peak the Q to see the
actual effect on inductor Q.  You can also use this approach to check on
coupling between coils, etc.  This can be of great help in selecting an
enclosure and for layout within filters.  The Q-meter will also let you
determine the inductance at a given frequency.  Even in an air wound core
the inductance will vary with frequency and there will be issues with
self-resonance.  This can be an issue with the large inductances needed for
very small antennas.  The Q-meter is a multi-purpose tool.

 

73, Rudy N6LF