OK, you guys are starting to worry me.
I just bought 4 more sections of Rohn 45 to get my 70-footer up to 110'
in preparation for putting up my dream antenna - an M2 10-30LP8 Log
Periodic. 115' seemed like a good height for this antenna, is it
actually possible this is TOO high?
My only goal is WAZ on 30 through 10m. I am not a contester.
Larry N8KU
Cqtestk4xs@aol.com wrote:
> In a message dated 1/19/2008 4:15:10 P.M. Greenwich Standard Time,
> gdslagel@yahoo.com writes:
>
>
> I've been using the HFTA software to try and get an
> idea of the optimum distance to stack a couple yagis
> for best performance. I'm stacking 10/15/20
> tribanders for increased performance. I was really
> surprised that on most bands the optimum performance
> seems to be with them separated by only about 10'...
> for instance 65' and 56'! I expected it to be more
> like 20' to 30'!
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> There is a caveat somewhere about this from N6BV. It is something
> like...when using very close spacing (like 10 feet) for HF antennas, the HFTA
> program
> by N6BV will give false results.
>
> If your top antenna height is going to be 65 feet, it would be in your best
> interest to have the other at 32 feet if you are going to operate all bands.
>
> It is a little too close for 20 but should do well on 15 and 10...assuming
> you are running a garden variety tribander of normal boom length.
>
> The HFTA is a wonderful tool if used with caution. Out here in a VERY
> mountainous terrain N6BV's program was invaluable in designing my stacks. I
> wanted to stack three KT36XAs but I found that with my terrain anything
> higher
> than 90 feet was a total dud for 20 through 10 meters. The result will be
> 90/56/29. But, that was an optimization for my QTH.
>
> I too was amazed with how much gain I could achieve with spacing of 10 feet,
> until I read the instructions for HFTA. Generally you will need a minimum
> of .5 wavelength for the stacks to start to play and from what I've read,
> .65-.75 plays about the best. Of course this depends on boom length.
>
> I hope this helps.
>
> Bill KH7XS/K4XS
>
>
>
>
>
>
>
> **************Start the year off right. Easy ways to stay in shape.
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--
Larry N8KU
l o n g w i r e . c o m
HF - DX - CW - Digital
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