[Amps] Re: compact coils...

[R.Measures]

On Feb 15, 2005, at 11:58 AM, ToddRoberts2001 at aol.com wrote:

> In a message dated 2/15/2005 2:00:42 PM Eastern Standard Time, 
> df3kv at 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