Re: Building a variable inductor ?

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

Original poster: "J. B. Weazle McCreath by way of Terry Fritz <teslalist-at-qwest-dot-net>" <weazle-at-hurontel.on.ca>


Hi Dan, Coilers,

Another option if you only need to vary the inductance slightly,
which should be the case for off-axis tuning anyway, is to make
the coil compressable.  By varying the length of a helix wound
coil you alter the inter-turn spacing and hence the inductance.
I have a six meter amateur band amplifier that uses this method
to tune from 50 to 54 mHz. in the output circuit of the tube
along with a fixed value capacitor.  In a typical Tesla coil
application you would only need to tune tens of kilohertz.

73, Weazle, VE3EAR/VE3WZL

"Don't take life so seriously, nobody has survived it yet!"

Listening: 7,055, 147.030+, and 442.075+
http://www.hurontel.on.ca/~weazle