[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
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