Antenna coils Traps

[Fred Wittman]

Glen Zook wrote:

>Except he said that they were loading coils and not
>traps.  Loading coils are just inductors (no
>capacitors).  Although they are "self resonant" (with
>"stray capacity") at some frequency, their primary
>purpose in life is to lengthen the wire electrically
>while maintaining a shorter physical length.
>
>If truly a trap then the length of the 40 meter
>antenna would probably be considerably longer than 38
>feet.  Of course, due to the inductive effects of the
>traps the total length would be different from the
>"normal" length of a half-wave dipole for 40 meters. 
>If they were traps for 20 meters or 10 meters (traps
>would not be needed for 15 meters due to the 3/2
>wavelength factor) then the proper place would be a
>little over 8 feet out from the center insulator for
>10 meters and a little over 16 feet out for 20 meters.
>
>Glen, K9STH
>
>
>--- "G. Lofstead" <jerrylofstead at BELLSOUTH.NET> wrote:
>
>If they are Spiro's, send him an Email and ask. 
>Otherwise, they normally would go out about 2/3 from
>the center.   I use a trap dipole on 80 & 40 M. Your
>traps may go at the 20M dipole end length... You get a
>40 & 20 M dipole...
>
>
>
>
>
>
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>
>
>Glen, K9STH
>
>Web sites
>
>http://home.comcast.net/~k9sth
>http://home.comcast.net/~zcomco
>
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I've always heard that loaded dipoles were notorious for generating 
harmonics, for that reason I've never used one.  An off-thread remark I 
admit, but...any thoughts?

Fred - KG6NYK

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