[TowerTalk] Slipp-Nott

[N7KA at comcast.net]

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