[TowerTalk] shunt-fed tower question

[Marc Wullaert]

My 80 feet not insulated selfsupporting tower (see qrz.com) is for years my
best 160m transmitting antenne.
radials are mostly 1/4 on 160m but I have shorter ones also like 10m !
I have a kt34xa and 40cd-2 40m on top.
What I did is connected both antennes with a heavy wire at the the
booms/plates to the top
at the tower.
All cables are running inside the tower.

shoud be no problem with your system !

Marc on4ma
----- Original Message -----
From: "Richard W. Harris" <Richard_Harris at byu.edu>
To: <towertalk at contesting.com>
Sent: Wednesday, August 17, 2005 12:03 AM
Subject: [TowerTalk] shunt-fed tower question


> Hi,
>
> I have never done this but am willing to try to shunt-feed my 72-foot
> 3-section motorized crankup tower to try to get on 160M.  I was told by
> someone that I would have trouble doing this if my tower is not
> insulated from the base.  I've been reading the ARRL antenna handbook
> and Low Band DXing by ON4UN and from the figures I see and the text I
> have read I have never heard about having the tower insulated from the
> base.  Here is what I have and also what I am interested in doing.  Any
> help would be appreciated:
>
>
>
> My setup consists of:
>
> 72 ft 3-section motorized crankup
>
> 12-element  7-band antenna at 74 ft (for 10-40M)
>
> Tower is anchored in a block of concrete 4' x 6' x '9'deep with 3 large
> j-bolts
>
> Currently there is no wire connection from tower to earth ground
>
>
>
> I have plenty of room in 3 directions to run ground radials out between
> 80 and 125 feet.  The 4th direction has a small building about 6 feet
> west of the tower.
>
>
>
> I was planning on running wire on all three legs of the tower to insure
> good section electrical connection and then connecting the tower base to
> the ground radial system I have not yet installed.
>
>
>
> My coax for the beam and rotor control cable will be run inside the
> tower and then into a 3" conduit underground to the shack about 90feet
> from the tower.
>
>
>
> I was planning on dropping a vertical wire from the top of the tower to
> ground and using a dip meter to measure electrical length and then plan
> the remainder of the installation based on the measurements I get.  I
> have a couple of good vacuum variable caps for the gamma or omega match
> to allow me to tune for 80M or 160M if this is possible with my setup.
>
>
>
> My tower is not insulated from the base and this is my biggest question
> but any help/suggestions would be appreciated.  I was a bit confused by
> the comment that my tower needs to be insulated from the base.  Is this
> correct?
>
> Thanks and 73,
>
> Richard - KJ7CU
>
>
>
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
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>
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