To everyone who provided such helpful responses concerning the 30M sloper
antenna. I really appreciate the input everyone gave such great responses
and helpful hints. I am going to run my 30M sloper from my tower at the
45ft level. Another point to mention is that I use an Ameritron RCS-8V,
remote coax switch so the feedline goes up to the ~50ft level to the
switch then a short piece of coax will return back down the tower about
4ft to the feedpoint. I don't think this will cause any problem but we'll
see when we get there:-).
Here is a summary of all the responses that I received RE: 30M sloper:
David, I have had much success with slopers. Suggest a 10 to 12 turn
coaxial balun at the feed point on the tower. Tom K4XG
You might also try the following antenna -- I forget what it's called
but it was written up in QST 1-5 years ago. It's a dipole installed
as sideways vee. It is fed at the center with the coax coming straight
back to the tower from the feedpoint. It is a directional antenna.
You'd likely have to diddle less with this antenna than you would with
a sloper.
|\
| \ <= dipole
| \
tower => | /\ direction of max radiation =>
| / \
|/ \
| \ <= support rope from feedpoint to ground or other
point
| \
Good luck and 73!
Ron (W8RU).
majewski@erim-int.com
Check out the ARRL Antenna Handbook...my issue it is on page 4-15. The
formula is Ft=260/frequency. I found that 25' 6" was ideal. Connect the
outter braid to the tower and with an insulator run the center to the
antenna
wire. I use a coax rf choke at the attachment point. It is 6 turns 6"
in
diameter of the feed coax. Just wind it and secure it with tape or wire
ties. This antenna works best with a beam antenna above it.
Have fun...Tom k0zm...Olathe, KS
Couple of items to consider as you assemble the antenna:
1. When you tie the braid to the tower, ensure that you get
a good electrical connection. Zinc plating on the tower
is NOT a particularly good electrical connection. A small
drilled hold in the tower, with a good stainless steel
screw will help ensure that you get a good connection.
2. Instead of just attaching ONE piece of wire to the coax
center conductor, you can attach two or three wires of the
approximate same length. Then, stretch them out by say 10
to 20 degrees from each other. You effectively have a broad-
band antenna here. Years ago I did this for 160 meters from
the top of my 130 foot Rohn 45 tower and it was an excellent
antenna. I used 3 wires (actually I used the outer shield of
junk RG-59U coax----scrapped by the local CATV company----as
the actual antenna wire.) and spaced them about 15 degrees
apart. I called it my "Three legged Sloper".
3. Keep the angle of the antenna wires away from the tower by at
least 45 degrees. In other words, make the wire that connects
to the coax center conductor out as horizontal as possible. Get
it away from your tower at the bottom as much as possible.
4. As you bring your coax from the antenna down the tower, keep it
as close to the tower legs as possible. Don't let it flop
around in the wind, and bring it down the tower as far as
possible
before you bring it out toward your shack.
5. Make sure to build in a 'water-drip' loop in the coax where the
center conductor and antenna wire are soldered together. You
want
to avoid water leaking down in your coax, between the black outer
plastic coax encasing and the shield, or down the center
conductor..
I can assurre you the water will get down in their in you point
that center conductor-antenna connection up into the air. Then
you will eventually see water in your shack.
6. There are probably more things that I can't remember, but these
are the ones I recall most vividly.
Hope some of this helps David. Good luck.
73
Dale K5MM
David E. Shelton, RN
KU4IT@juno.com
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