Half sloper mounting
 

I intend to try a half sloper on my TX455 tower (with a tribander on top).
I can connect the sloper to the top of the tower (about 55 feet up) or to
the top of the middle section (about 38 feet up). Other things being equal,
I would prefer the middle section (for maximum separation from an inverted V
connected to the top section and at right angles to the sloper). The tower
is grounded and will have a reasonable number of radials (when I can figure
out how to best attach them).

I know that half slopers have been debated here and many other places and
provide considerable confusion for most of us. I think I understand that
the tower provides most of the radiation and the sloper wire is more a
matching device than a radiation device. Should I expect significant
improvement with a tower-top connection instead of a middle section
connection? Would it make much difference? Are these things so unpredictable
that experimentation is the only answer?

Bill
W2WO

On Mon, 11 Oct 2004 23:20:19 GMT, "Bill Ogden"
wrote:

I intend to try a half sloper on my TX455 tower (with a tribander on top).
I can connect the sloper to the top of the tower (about 55 feet up) or to
the top of the middle section (about 38 feet up). Other things being equal,
I would prefer the middle section (for maximum separation from an inverted V
connected to the top section and at right angles to the sloper). The tower
is grounded and will have a reasonable number of radials (when I can figure
out how to best attach them).

I know that half slopers have been debated here and many other places and
provide considerable confusion for most of us. I think I understand that
the tower provides most of the radiation and the sloper wire is more a
matching device than a radiation device. Should I expect significant
improvement with a tower-top connection instead of a middle section
connection? Would it make much difference? Are these things so unpredictable
that experimentation is the only answer?

What band?

I'm running a half sloper on 160 to the South. It anchors to the
tower at the 96 foot level which give me pretty close to 45 degrees.

The same angle could be obtained at anything over 48 feet on 75
meters.

I also have half wave, center fed slopers on 75 to the NE and to the
http://www.rogerhalstead.com/ham_files/tower.htm NW although I have
the one to the NW down at the moment. There is a center fed, half
wave sloper for 40 meters that runs just slightly south of West. The
tower is guyed with Kevlar lines so they do not interfere with the
antennas. At 100 feet is a Hygain TH-5 tri-bander, a 7L 6 meter C3i
yagi at 115 feet and stacked 11s on 440 and 12s on 146 MHz at 130
feet. How much effect all that stuff on top has on the half sloper? I
have no idea.

All of the feed lines, rotor cables, and control lines were on the
outside of the tower. I have moved all but one bundle of coax to the
inside. That made a noticeable change in the tuning on the half
sloper albeit a small one. It made no difference to the half wave
center fed slopers. I hope to get the last of the cables moved to the
inside of the tower within a week.

My take on the half sloper is basically the antenna is a sometimes
thing. Mine worked on 160 with the first try although I did end up
shortening it about a foot to hit the whole band. It does appear to
be more sensitive to the sourrounding area than the half wave, center
fed slopers on 75. As it works agaisnt the tower, I doubt radials
would make much difference, but I don't know for sure.

My feed point is a female N-connector (threaded for chassis mount with
a nut and washer) mounted in a bracket made of 1/8" thick X 1" wide
Aluminum stock about 8" long. The end is drilled for a slip fit of
the chassis connector and then bent at 90 degrees. I use two SS hose
clamps around the straight part of the bracket to hold it to the tower
leg. The end of the antenna goes through an egg strain insulator
which is supported from the tower using about a foot of 1/8" Nylon
Rope. A jumper runs from the insulator to the center conductor of the
N-connector. The connector is throuroughly coated with liquid
electrical tape. There is about 8 feet of coax from the feed point to
the remote antenna selector switch through the inside of the tower.
The feed line to the remote switch comes up the inside of the tower.

I don't have any photos up yet that show the half sloper connection
but hope to soon.

It would be interesting to try one on 75 mounted at the same height
and compare it to the half wave, center fed slopers on the same band,
but I'm running out of space.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


Bill
W2WO

On Wed, 13 Oct 2004 21:25:24 GMT, Roger
wrote:

On Mon, 11 Oct 2004 23:20:19 GMT, "Bill Ogden"
wrote:

I intend to try a half sloper on my TX455 tower (with a tribander on top).
I can connect the sloper to the top of the tower (about 55 feet up) or to
the top of the middle section (about 38 feet up). Other things being equal,
I would prefer the middle section (for maximum separation from an inverted V
connected to the top section and at right angles to the sloper). The tower
is grounded and will have a reasonable number of radials (when I can figure
out how to best attach them).

I know that half slopers have been debated here and many other places and
provide considerable confusion for most of us. I think I understand that
the tower provides most of the radiation and the sloper wire is more a
matching device than a radiation device. Should I expect significant
improvement with a tower-top connection instead of a middle section
connection? Would it make much difference? Are these things so unpredictable
that experimentation is the only answer?

What band?

snip
My take on the half sloper is basically the antenna is a sometimes
thing. Mine worked on 160 with the first try although I did end up
shortening it about a foot to hit the whole band. It does appear to
be more sensitive to the sourrounding area than the half wave, center
fed slopers on 75. As it works agaisnt the tower, I doubt radials
would make much difference, but I don't know for sure.

My feed point is a female N-connector (threaded for chassis mount with

Oops. I have N-connectors on all of my cables, but I used an adapter
to a PL-259 with a round SO-239 mounted in the bracket.

The images of the construction are now up on
http://www.rogerhalstead.com/ham_files/tower.htm at the bottom of the
page. It's a large page and even with the small images may take a
while. I'll eventually put the construction stuff on another page.

Sorry the images are all at, or close to ground level. I don't have
any of the actual installation. Maybe next time I'm up there. I do
make it several times a week in warmer weather.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Thank you (various people) for the comments about half sloper attachment
points. I think the result is that the half sloper should be attached as
high as possible on my small (55') tower. (It is intended for 160-40
meters.)

Bill
W2WO