[TowerTalk] shunt feed
Craig Clark
jcclark at wildblue.net
Tue Nov 15 21:03:43 EST 2005
>
>OK, with all this talk about shunt feeding - maybe I am ready to take the
>plunge. I am usually not so stupid but I have read about shunt feeding and
>end up with more questions than answers.
>
>My tower is a 45G with an Optibeam OB17-4 on top (40 foot boom - 17
>elements) and then a WARC-7 (7 elements on a 14 foot boom) about 12 feet
>about the Optibeam. So, quite a bit of top loading and with 80 foot tower I
>have wondered about shunt feeding for 80 and esp 160 meters.
>
>Can someone point me to a good step by step resource and will you also
>answer my questions afterwards? I would love to do better on 160 meters.
How high is the tower? Do you have guy wires? Are they insulated from
ground? If not, stop here and develop a plan B.
Put lots of radials down.
Run a wire or wire cage (6" - 12" on a side) to the top of the tower
spaced 2-3 feet. Ground this cage to the top of the tower.
Put a step-up L network at the base; you are matching 50 ohms to
~~200 ohms (series L, C to ground on the antenna side.)
Tune for minimum SWR
You are good to go.
Craig K1QX
73, Craig Clark, K1QX
PLEASE NOTE NEW EMAIL ADDRESS
JCCLARK at WILDBLUE.NET
RADIOWARE AND RADIO BOOKSTORE
PO BOX 209
RINDGE NH 03461
603 899 6957
WWW.RADIO-WARE.COM
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