[600MRG] What is the best way to tune a coil?

[Ralph Hartwell]

Gaah!  I hate lists that do not automatically let you reply to ALL instead
of the original poster!  Paul just got an extra copy of my message that was
supposed to be sent to the list, not to him.  SRY Paul.


> I was going to take an old metal water bucket, put a few rocks in it and
tie it to a rope to lower it (or raise it) into the center of the coil.

Unfortunately the iron in the bucket will have a very RF loss due to the
circulating current in the iron caused by the magnetic field of the coil.
The system will  dissipate a lot of the power heating the bucket.

Now, if the bucket made out of pure silver, it might work reasonably well.
<G>


The only reasonably effective methods of varying the inductance are either
to use a variometer or multiple taps on the coil.  Using taps on the coil
will give you the least loss since you have only as much wire in the circuit
as is required for the desired inductance.  The variometer has somewhat
higher losses than a tapped  coil but it is much more convenient and lends
itself more easily to remote operation.


Best DX & 73,

Ralph  W5JGV - WD2XSH/7