I have a very small yard and a 70ft tower with a beam on top. I want to put
up transmitting antennas for 80m and 160m. For the space I have, some form
of vertical seems the best. I do not want to shunt feed the tower as a
vertical because the feed lines run a long way to the tower from the house
along a messenger cable that is 10ft above the ground (no buried coax). The
feed lines would become part of the radiating system and would put a lot of
RF into my shack.

Shunt feeding the tower is probably the simplest option.
Why not coil the feedlines into chokes when they leave the tower, or
put stacks of ferrite beads on them to keep RF off them?

Torsten
N4OGW

On 10 Mar 2005 13:18:18 -0600, wrote:


I have a very small yard and a 70ft tower with a beam on top. I want to put
up transmitting antennas for 80m and 160m. For the space I have, some form
of vertical seems the best. I do not want to shunt feed the tower as a
vertical because the feed lines run a long way to the tower from the house
along a messenger cable that is 10ft above the ground (no buried coax). The
feed lines would become part of the radiating system and would put a lot of
RF into my shack.

Shunt feeding the tower is probably the simplest option.
Why not coil the feedlines into chokes when they leave the tower, or
put stacks of ferrite beads on them to keep RF off them?

Torsten
N4OGW


Or, use an UNUN.

I am not familiar with the specific antenna you are describing, but in
the ARRL Antenna book, it describes an antenna where the coax is taken
up the tower where the shield is grounded to the tower and the other
half of the 'dipole' is a wire strung out to where ever.

It's just an option.


--
73 for now
Buck
N4PGW

I agree with Torsten. You need make no changes to your present run of
cables (along a messenger cable) other than adding clamp-on chokes to each
wire (including the messenger cable). If the "run" is a significant part of
0.25 WL at a frequency of concern, you may find it desirable to place a
second set of clamp-on-chokes about 0.25 WL from the first set or near the
house entrance (whichever comes first).

You will need radials in order to have reasonable efficiency. An
impedance bridge will help in finding the connection spot on the tower where
the real part of Z is 50 (or 70) ohms.

Let us know what you do.
73 Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:
wrote in message
...

snip

Shunt feeding the tower is probably the simplest option.
Why not coil the feedlines into chokes when they leave the tower, or
put stacks of ferrite beads on them to keep RF off them?

Torsten
N4OGW