I have a sloper for 80M on my 64-foot SS tower and it seems to work
well (it takes power and people hear me barefoot.) The wire is about 67
feet long and the coax shield is tapped to the tower at the 50-foot level.
However, as others have already said:
o YMMV - so make the initial wire much longer and fold back along its
length (use bronze split bolt nuts) until you achieve the SWR results you
want. Don't trim the wire as you go because
o When you add the top-loading from Yagis, you will undoubtedly need to
change the length of the wire somehow. Keep the full wire length in the
system until that time. Remember the old saying, "I cut it twice and it's
STILL too short."
As for shunt-feeding the tower, I've done that here, too, on 160M. The
RF radials are seven #18 wires, five of which are 100 feet long and two are
35 feet or so (the distance to the back yard fence. The lightning ground
radials are three #2 solid copper wires totalling 135 feet or so and welded
to 12 ground rods. I think both systems work in harmony to provide
acceptable performance on 160M, and possibly 80M, too.
Gene Smar AD3F
----- Original Message -----
Sent: Wednesday, December 29, 2010 6:59 PM
Subject: [TowerTalk] Length of Sloper?
> Hi Guys,
> I'm installing an 80-meter Sloper on a self-supporting 60' tower. (no
> guys) I don't have a MFJ-259 or other antenna bridge with me so I'd
> appreciate your thoughts to help get me in the ballpark. The 80-meter
> Sloper will
> attach to the tower at the 55' level. Currently there are no other
> on the 60' tower. A couple questions:
> 1) With no other antennas on the 60' tower, do you think the length of the
> Sloper wire will be close to the formula 234/freq? Or do you think the
> Sloper will wind up needing to be longer or shorter than 234/freq?
> 2) The once I get the Sloper tuned for minimum SWR on 80-meters, if I
> add a Tribander to the top of the tower I'll no doubt need to re-tune the
> Sloper, but do you think the Sloper will need to be shortened or
> lengthened after the Yagi is added?
> Thanks & 73,
> Dick- K9OM
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