The new F12 "N" element for 40 meters, referred to below, is linear loaded. A
few more specifics:
The elements are about 85% of full size. There is less linear loading than older
LL elements.
The LL occurs 7-8 feet from the boom, and goes OUTWARD and back. This leaves the
center 15 feet, which will carry the highest current, uncanceled or unfolded
(use your favorite term).
The LL is rigid rod (not flexible wire), and has nothing to do with the element
support system, which uses non-conductive, no-stretch cord. In addition to being
more efficient, the frequency settings will not be affected by how tight one
pulls the supports, as in prior designs.
The LL shortens the elements enough to reduce element weight 50% from full-size.
Personally, it has to this point answered the issues I have had with LL elements
prior.
(No affiliation with F12. Will be putting up a F12 Magnum 340N, and we will
see.)
- - . . . . . . - - . . . . - - . . - . .
73, Guy
k2av@contesting.com
Apex, NC, USA
----- Original Message -----
From: <K7LXC@aol.com>
To: <KI7WX@aol.com>; <towertalk@contesting.com>
Sent: Wednesday, October 20, 1999 9:48 AM
Subject: Re: [TowerTalk] 402CD + Skyhawk part II
In a message dated 99-10-19 21:50:54 EDT, KI7WX@aol.com writes:
> The bandwidth issue rules out a lot of shorty 40s and the interaction
issues
>
> clobber others. So how about using interlaced beams at the top? Say
20/40
> with 10/15 over it and a pair of stacked tribanders sidemounted below.
This
>
> could all be fed with a stackmatch and remote switch to split power and
> phase
> the antennas together. More trouble than tribander + 40M beam, but might
> work out. If the interaction issues are related to 15M one could go
20/40
> with a big 10M yagi over it and forgo the highest 15M beam.
>
> So, lots of options, I'm just curious what people have done in the real
> world. I think I'm going to put some effort into tracking down a 402CD...
The 402CD is a wonderful little antenna so you can't go wrong by
installing one. And it's got 250 kHz of bandwidth.
Here are a couple of developments in this arena. There are some guys in
W6 who have developed coils for 75M beams to replace the linear loading. They
claim that since the linear loaded wires (ala F12) are some distance from the
aluminum element that the efficiency goes down. Apparently most of the W6 big
gun 75M boys have converted with good results. Now I understand that they
have coils for 40M beams too. I've never been too thrilled with linear loaded
antennas so this might be a way to get the best of both worlds - smaller
antenna with more efficiency. I don't remember the name of the company or how
to get ahold of them - sorry. It's W6KW and his cronies.
The other thing is that apparently F12 has designed a new LL antenna
that doesn't self-resonate on 15M. They changed the design and it sounds like
there is little or no interaction so this might be worth investigating.
Unfortunately it's a LL design too.
Even with your proposed interlace antennas you still have to allow
10-12 feet separation but going with F12 designs means that the antennas will
work FB.
Cheers, Steve K7LXC
Tower Tech
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