Concerning,
"Dear Luca,
For that kind of power output you will need a Type 67 core,
permeability=40. You should opt for at least a 2.4 inch core
or better, as well.
The core you fabricate should have two or three layers
of ferrite, surrounded by three (3) layers of
3M Glass tape.
The wiring you utilize should be PTFE (Teflon) coated
of at least 2mm diameter.
The core should be mounted on a ceramic standoff, away
from the chassis, preferably in the tank cooling airflow."
Respectfully,
Hal Mandel / W4HBM
Luca,
I respectfully disagree with just about all of the above info. Ferrite
is not suitable for this resonant circuit application. (If you did use
ferrite, you do not need the glass tape--ferrite is a very good
insulator). There is not much voltage present in this part of the Pi-L,
so you don't need teflon insulated wire. The RF field is fully contained
inside the core, so you can mount it close to the chassis, say on a
piece of un-clad PC board. Gauge #14 or #12 "enameled" wire is
adequate. There will be negligible heat generated in this part of the
Pi-L circuit. Powdered iron is the proper core material, with two layers
of glass tape or equivalent.
73, Roy K6XK
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