[TowerTalk] re:Force 12 Stack

[Jay Terleski]

Ron,

The C4 C3 stack will work fine.  I am guessing you will use the single
feed line models.  You must compensate the Stack by not using identical
feed line lengths but feed one with a small delay line length of coax to
compensate the driven element (sleeves) difference in horizontal spacing
when pointing in the same direction.


The other thing I would suggest is that you shorten your proposed
spacing to 27 ft.

C3s are short booms and modeling has shown us that 27 feet is about the
best and widest compromise for gain and pattern.  

Also model the stack to make sure your setting these antennas to obtain
the pattern you want.  At 100 feet and 75 feet you will have a very good
DX signal but probably not so good a signal to US.  You might consider a
third C3 at 50 feet.  Then you could also put the upper one in phase
with the one at 50 feet and have a very wide spaced stack.  This
provides high angle lobes for E-skip and F skip close in work.

The lower one can also be used alone.  Allowing for even more take off
angles.


Jay, WX0B


Ron Arnett wrote:
> 
> I am seriously considering stacking two Force 12 multi-band beams on a 100
> foot tower to be constructed, hopefully later this fall.
> 
> I would like to place one triband antenna at the 65 foot height and a
> tribander with the 40 meter 2L extension at the 100 foot level.  I am
> considering the classic C-3 7L(18 foot boom) at 65 foot with either the
> C-4XL 9L(30 foot boom) or C-4SXL 8L(23 foot boom) at 100 foot.
> 
> I will phase the two beams on 10, 15 and 20 M so it would be very desirable
> to have them electrically matched as much as is possible.
> 
> Questions to the reflector are: Is this a good plan (these will be my only
> HF antennas) and which of the F12 antennas are the best electrical match?  I
> am assuming that the better electrical match will perform better when
> phased.  Please let me know of any fallacies in my logic.
> 
> Thanks.
> ----------------
> Ron Arnett
> KG5AQ
-- 
Jay Terleski
WX0B - Array Solutions
www.arraysolutions.com

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