[TowerTalk] Element fastening - a data point from F12 75/80m dipole

[Grant Saviers]

I'm converting a Force 12 180C 75/80m dipole from linear loading + 
relays to the Seco Tornado variable inductor at the feedpoint (a custom 
design) for full band coverage (85' long and EZNEC predicts a 25 ohm 
feedpoint Z).

This antenna is very experienced (15+ yoa); I am the third owner, but it 
generally is in good shape except where a tree caught a tip section 
during the last take-down, an easily replaced 0.375" od section.  
Fortunately, it was assembled with anti-seize or Noalox and comes apart 
easily.

What is interesting is that every bolted joint is solid and every 
riveted joint is loose.

The original design has two bolts in line for bolted sections (2.5" od 
down to 1.25" od) and three rivets in line for all smaller od sections.  
So for every riveted joint I am adding two bolts at 90 degrees in 
between the rivets.  The new bolt sizes range from 1/4-20 to 6-32, all 
18-8 stainless and nylock nuts.  Each joint is now tight.

I analyzed the original design with Yagi-Mech (without LL wires or guys) 
and found that the 1" od section where the LL wires previously attached 
is the weakest section, so am reinforcing that section with 0.875" 
tubing (and I need to modify this section anyway).  The unguyed survival 
is now 75mph at 100' exposure B, no ice.  With Phillystran guys 
replacing the LL wires I expect 85mph survival, but that is very hard to 
analyze.

"up the tower" hopefully in a week or two.

Grant  KZ1W