PVC tubing to stand off the line from the tower at the top, bottom and a few
places in between seems to work. 12" spacing should be sufficient for 600
Ohm open-wire, a bit less should suffice for ladder line, which will have
closer conductor spacing. I've used stainless steel screw-eyes threaded
into the PVC tubing, and spaced apart the same distance as the conductors in
the open wire, to let the line "slip" up and down a bit, rather than be held
rigidly in place, so the line can bob a bit in the wind, but never come
close to touching the tower.
(I've also used "nothing" to stand off 450 Ohm well-insulated ladder line,
for years, with no measurable ill effects at all. The line normally hangs a
few inches away from the tower, but in the wind, can bang into the tower --
doesn't seem to matter much. Even running 1500W through it when this
occurs, I've never had it "flash" through the insulation, and never note any
large changes in match.)
-WB2WIK/6
"If everything seems under control, you're just not going fast enough." -
Mario Andretti
> -----Original Message-----
> From: k0myw@att.net [SMTP:k0myw@att.net]
> Sent: Friday, August 23, 2002 10:12 AM
> To: towertalk@contesting.com
> Subject: [Towertalk] Ladderline near tower
>
> I'm thinking of trying a dipole fed with old-
> fashioned 600-ohm ladderline.
>
> It occurs to me that, because the dipole will be
> center-hung from my tower, that I might ought to pay
> more attention to interaction possibilities with this
> feedline than when feeding a wire antenna with coax.
>
> Any advice/warnings about how to approach a tower-
> hung dipole with open-wire feeders?
>
> Mike, KØMYW
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