> Mike Fatchett W0MU wrote:
>
I have a bunch of Cushcraft 40-2CD XM240 elements hanging around.
Could the elements be shortened to work on 30m?
Yes, the elements can easily be made resonant on 30 meters. The
late Jim White, K4OJ did that with a D40 20+ years ago. Loose the
capacitance hats and shorten the tips beyond the coils by about
12".
The problem will be efficiency, the coils will be very close to the
tips which means increased coil losses ... above the already high
losses due to the long narrow coil.
The elements are already 22+ feet long. Replacing the 18" coil with
a 36" +/- section (will need 7/8", 3/4' and 5/8" steps to match the
tubing sizes before after the coil) would be the only mechanical
changes to the elements ... shorten the boom to 11-12' (take off
the two outer sections). I'd even consider a DE-DIR design for the
shorter boom/elements since bandwidth is not a problem on 30.
73,
... Joe, W4TV
Mike Fatchett W0MU wrote:
I have a bunch of Cushcraft 40-2CD XM240 elements hanging around. Could
the elements be shortened to work on 30m? They all have coils and a
capacitance hat as expected.
The boom would also need to be shortened a bit.
Mike W0MU
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|