Of the general rule of thumb is, shorter booms can have smaller spacing,
to a point. Larger longer booms require more spacing than short booms. 28
foot spacing works quite well for 6/7 elements. At least it does for me.
K4XS
In a message dated 2/21/2015 6:42:06 P.M. Coordinated Universal Time,
john@kk9a.com writes:
I have never modeled tribanders but most of my monobanders have around 1
wavelength spacing. 28 foot spacing on 10m is not too wide in my opinion.
John KK9A
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Tribander Spacing
From: Pete Smith N4ZR <n4zr@contesting.com>
Date: Fri, 20 Feb 2015 15:56:32 -0500
Assuming you meant a second C-3, I did extensive modeling of pairs of C-3s
back in the late 90's when I put my stack up. There was an NCJ article, but
if you like I can try to dig up the manuscript here.
I wound up with C-3Es at 97 and 69 feet. It's too wide for the best 10m
pattern and not wide enough for optimum on 20, but it worked out to be the
best overall compromise. I would have put up a third antenna at around 35
feet, but the tower would have been marginal.
Your case will depend on local terrain, and on take-off angle data for your
part of the country. HFTA modeling will give you figures of merit for
various paths that you can use to reach the best compromise, given your
location and, perhaps, the prospects for 10M in the next cycle.
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|