[TowerTalk] HyGain 155CA dampening rope

[Jim Thomson]

What else that works instead of rope,  is either  .125 SS cable.... or  .09375  SS cable..
or galvanized winch cable in the same 2 sizes.  Then a SS hose clamp to hold the cable
to the outside of the  tip.  IE: cable run down the inside of the entire ele, then out the tips, then
folded back on the outside of the tips, then SS hose clamped down. 


You need a bit of weight to kill the vortex shedding.  A buddy across  town had his 204BA up
100 ft on 25G.... and when he finally took it down, all 8 x  ele  tips were almost ready to pop 
out the ends.   The oem Hy – gain ele clamps did not do the trick.   The winds were strong up
there..and the tips and also inboard ele sections  started to migrate outwards. 

I had a 204BA with a wilson 5 el 15M yagi stacked.. plus a 5 el, forget the brand name.. 10m yagi,
back in the 70s.   No rope on any of them.   Both the 20 + 15m yagis  would vibrate like crazy, in a 
light breeze..but only when turned a bit at an angle to the wind.   But the vibration was aprx 6 ft 
out from the boom, not the tips.   They would both vibrate up 3 inches..and then down 3 inches,
6 inches in total.  Later, my hb 20m yagi  did the same thing, but nothing ever broke. 

My 20 + 15m F12 yagis, plus my buddys  F12 5BA  never had a vibration /  vortex shedding issue,
regardless of wind speed, or yagi orientation to the wind.  They just dont vibrate... no rope or cable
required.  
The F12 yagis dont have the swedged els.  The 20m eles use a  simple  .375 - .5 – .625 – .750 – .875 – 1. – 1.125
taper to the eles.   The 1.125 is double walled. For even  greater wind speed capability, the 1.00 section can be 
double walled as well. 
Baffles me why hy-gain et all, just dont re-design the ele taper on their yagis..and eliminate the swedges. 
You dont require the large OD sections in the middle, like the 1.25 sections on the 204BA.   You can run the
various tapers through either of the mech software programs to see the effects right away.   Even if you wanted 
to use 1.25 tubing the center,  you still  taper off with the 1.125 – 1.00 – .875 etc etc.   Still wont vibrate.

Another fellow across town had his internal rope start to migrate out one ele tip...  with several inches of it
flapping in the breeze.   It had cut loose at both ele tips..and was free to migrate out either end.   Be careful
with what rope you use, if exposed and folded back on the outside, some of it can degrade with UV. 

Jim   VE7RF