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10/40 Close spaced stacking

Subject: 10/40 Close spaced stacking
From: K7LXC@aol.com (K7LXC@aol.com)
Date: Sun May 12 13:37:35 1996
In a message dated 96-05-12 11:15:29 EDT, you write:
>Okay, the glaciers have begun to recede enuff that two weeks ago I finally
>got the concrete poured for the 80' 45G. I've been tossing in my sleep all
>winter as far as what antennas to put on it. I have a K5RC VERY stout 20'
>mast (108,000 psi).
>My latest plans (all of these ants are on hand): 205 at top; 402CD 10 feet
>above 205;                         105 @ 5 or 6 feet above 402CD.  (15
>meters? sidemount later).
>Question: (1) Any experiences out there with close spacing of 402 and 105?

Hi, Matt --

      My opinion is that the antennas probably won't even see each other.
 Someone who has access to an antenna modeling program can give you more
specific info.  Since the 105 is the 4th harmonic, I don't think you'll have
any problems.
>          (2) What's the general consensus on pinning the booms to the mast?
>              What does this do to the integrity of the boom? mast?

      I wouldn't bother pinning the booms.  First, it'll take you forever to
drill through the VERY HARD mast.  Secondly, antenna system rotation is due
to mast slipping in rotato, NOT antennas on mast.  The Hy-Gain boom-to-mast
clamps will never slip.  I would upgrade the Cushcraft plate to something
more substantial.  If you're still worried, add another U-bolt and saddle -
more friction.

      I'm also not a big fan of pinning the mast to the rotator.  Instead of
the forces turning harmlessly, a pinned mast will find the next weak link in
the chain and it's usually the gears or brake of the rotator.  It's easier to
re-align the mast than replace a busted rotator.

73 and good luck.  Sounds like fun!    Steve   K7LXC

     TOWER TECH -- professional tower supplies and services for amateurs

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