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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