[TowerTalk] Press release Re: F12 ants !!

Jim Thomson jim.thom at telus.net
Thu May 11 12:54:49 EDT 2017


## Apparently,  JK antennas in CT,  will be building some select models of legacy F12 ants, yagis + verts.
But  each select  F12 ant will  be completely re-optimized to  NEC-4 pro standards.   EG, F12s  5BA has been
re-designed, with fewer eles, and more gain, better performance.  They will also be  completely
re-designed  mechanically  to  JK antenna  standards.  

##    F12 used the now obsolete  RS-222-C method for determining wind loading.
The problem with the 222-C spec is the effective area was used, instead of the actual projected area
of a cylinder.   IE, what F12 called  6.67 sq feet is actually 10 square feet.   You have to take the
old F12 square footage..and multiply by 1.5   to get reality. 
The calculated V max, using 222-C is incorrect.  Ken Garg at JK antennas uses the newer standard,
as in what you actually measure inside a wind tunnel.   Mosely, Hy-gain, M2 are still using the old 222-C spec. 
100 mph using the wind tunnel spec, = aprx  112 mph using the old 222-C spec. 
100 mph using the 222-C spec is in reality, aprx 92 mph using the new spec. 

##  new versions are built a lot stronger, handle ice loading,  and a real 100++ mph wind, etc. 
The re-designed select F12 ants will augment the superb, existing line up of JK ants.  

https://jkantennas.com/news.html

Jim  VE7RF


More information about the TowerTalk mailing list