Topband: 160 dipole on 80 & 40

[Tom Rauch]

> Help - I'm trying to use my 160 dipole on 40 & 80 but I'm
unable to tune
> it to any kind of resonance.  It's about 260 feet end to
end, center fed
> with 450 ohm ladder line then to a Nye Viking tuner.
Works great on 160
> and ALL other bands.  Any hints as to where to start?
I've already tried
> shortening and lengthening it but I'm working in the dark
without an
> analyzer.

Hi Dick,

The worse multiband length combination is an electrical 1/4
wl feeder or multiple used with a 1/2 wl antenna on the
lowest band. If you have a 160 dipole, you want to avoid a
"ladder line" feedline near 90-110 feet long.

The best combination is about a 1/8th wl (or odd multiple)
feeder, so the best feeder length with "ladder line" would
be about 50-60 feet or 150-180 feet with your 160 dipole.

The second issue complicating your system is the network in
the tuner. While many people rave about L or Pi networks
(the Nye really functions as an L network) they
unfortunately provide the narrowest matching range for a
given range of component values. You'll have to really watch
the feeder length with that tuner. It won't have the
matching range of a T network.

(By the way, I know the circuit looks like a pi....but
electrically it is behaves like a conventional L network for
most loads. The fixed C is not large enough to make it act
like a pi except perhaps on ten meters.)

73 Tom