On Feb 15, 2005, at 11:58 AM, ToddRoberts2001@aol.com wrote:
In a message dated 2/15/2005 2:00:42 PM Eastern Standard Time,
df3kv@aol.com
writes:
I remember an amp project in the ARRL handbook years ago
which used several pieces of ferrite rod taped together
and placed inside of one end of the tank coil to provide
enough inductance for 80 meters.
I tried that with my L4B for 160m, it worked, but the rods got very
hot
Powdered iron is more suitable for 160m tank inductors because it is
typically more resistant to saturating.
73
Peter
It has been my experience that ferrites and iron core cores tend to
saturate
and cause problems and heating in High-Z High Power circuits like in
RF tube
amplifier tank circuits. A lot depends on the power level used and how
big the
cores are. Ferrites and iron core cores work well in Low-Z broadband
High
Power circuits like transistor RF power amplifier output circuits. No
worry with
air-core coils saturating in High-Z high-power RF circuits except the
size of
wire or tubing should be chosen to reduce skin-effect heating. 73 Todd
WD4NGG
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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