Brilliant idea using Hy-Gain clamps. They do clamp well but unfortunately
the maximum mast size I think is 2 1/2 diameter. I use 3/8 or 1/2
aluminum plate, which is readily available cut to size at most of the
online metal companies and McMaster Carr. The hardware change can be done
without bringing the antenna to the ground.
John KK9A
To: dave arruzza <w1ctn@yahoo.com>
Subject: Re: [TowerTalk] Slipp-Nott
From: N7KA@comcast.net
Date: Fri, 20 Dec 2013 04:07:47 +0000 (UTC)
I think many folks are missing a very easy fix (modification) to many
antennas
that have poor boom to mast mounts.
I have a 52ft boom 5el 20M yagi (its heavy, about 170lbs) made from 2ea
TELREX
3el 20M yagis. My boom to mast mounting consists of a 1/2" thick aluminum
plate approx. 18" long and 12" high (surplus find). To secure the plate
to the
mast I used 2 pairs of the HyGain mast clamps, PN 102734, spaced about 4"
vertically apart to clamp to the mast. I enlarged the thru holes (8ea per
pair) to accept 7/16" hardened grade 5 instead of the 3/8", bolts for extra
strength. This antenna has been up for approx. 22 years and it has NEVER
rotated/slopped on my 2" mast (4130A519 alloy). It often sees winds in
excess
of 70-90+ mph during the monsoon season here is Albuquerque, NM.
Mounting the boom to the plate does not require as much effort since there is
practically no torque of the boom. U-bolts with saddles will work just
fine. I
used the standard TELREX mounting U-saddles.
OH, yeah, I used the same clamps on my CC 40-2CD, just 1 pair and it has
NEVER
rotated/slipped on the mast either.
The HyGain clamps) are the best kept secret when it comes to building a yagi,
and worth every penny they cost.
For antennas with 2" booms I used the complete HyGain boom to mast assy.
IMHO,
HyGain got this absolutely right.
Hope this is of some help.
Arne N7KA
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