This brings up a good question. I have access to a Rohn 25 tower
that is 60 feet tall. The base of the tower is located on top of a building
at ~40'. Fifteen feet of the tower is bolted to the side of a doghouse
structure that sits on the roof of the building (houses elevator motors,
air conditioners, etc). The tower is topped with a KLM 4 element
40 (102') and a KT34XA (114'). The parasitics elements of both
antennas are shorted to their respective booms with short #14
solid copper wire jumpers just in case they are needed as top
loading.
I would like to do something with the tower for 160 meters.
As I see it, there are two options (already have a dipole on
another tower) - #1 shunt feed the tower as an elevated
ground plane 45' below the KLM 40M4 (this is at the
rooftop level of the doghouse where the coax and rotor cables
break away from the tower and head over toward the shack).
#2 install a 1/4 sloper underneath the KLM 40M4. Any
thoughts from the group as to which is the preferred option
(right now I am leaning towards the shunt feed)? I would
use elevated radials (4 at 65') for the shunt feed arrangement.
Thanks!
Mike, W4EF.....................
----- Original Message -----
From: "ARNE GJERNING" <gjerning@flash.net>
To: "TOWER TALK" <towertalk@contesting.com>
Sent: Wednesday, January 02, 2002 9:34 AM
Subject: [TowerTalk] SLOPERS
>
> Mine works good, loads great. Feed point at 80ft. Wire length adjusted for
> min SWR. Bottom is about 3ft off ground (I go under a power line).
Direction
> of sloper is bottom toward EU. Top loaded with CC 40M at 100ft and 5el 20
> (52ft boom) at 88ft.
>
> I have to agree it seems to be a great advantage to have top loading.
DF2PY
> was amazed to see my large 160 "array" when he visited me first time. One
> night had 15minute SSB qso with Wolf on 160M. But his station is really
> great, RX and TX. BTDT.
>
> BTW, after being swept up in a village land grab, I can not put up any
more
> structures above 24 ft (damn zoning again). So am lucky to have this and
one
> 31ft tower that are up and "grandfathered in".
>
> 73 de Arne N7KA
> (only 106 worked on 160M but having fun)
> No beverages or other rx ant
>
>
> ________________________________________________________________________
> This list is sponsored by the new eHam.net Store. When you buy products
> like ICE filters, Array Solutions StackMatch, or M-Squared Antennas from
> the eHam Store for the same price you pay direct, a portion of the sale
> price goes to support this list. Check it out at http://www.eham.net.
>
> -----
> FAQ on WWW: http://www.contesting.com/FAQ/towertalk
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> Problems: owner-towertalk@contesting.com
>
>
________________________________________________________________________
This list is sponsored by the new eHam.net Store. When you buy products
like ICE filters, Array Solutions StackMatch, or M-Squared Antennas from
the eHam Store for the same price you pay direct, a portion of the sale
price goes to support this list. Check it out at http://www.eham.net.
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|