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Old May 3rd 08, 02:39 AM posted to rec.radio.amateur.antenna
Fred McKenzie Fred McKenzie is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 317
Default Octopus a real Doosey

In article ,
"HRBE" wrote:

I re-read N1GY's original and he mentioned in his article about the actual
placing of the whips.

I followed his directions and placed the 75m and 40m whips at right angles
to each other and the ather two pairs of whips in a like manner.

This then made the whole job a little easier, but the 20m whips are not as
sharp in tuning as the other pairs.


John-

I built the Octopus, but decided to go one further. I added a Ten Meter
vertical whip on top, thinking the other elements would act as an
effective counterpoise. It didn't work! Apparently a Ten Meter
counterpoise element is needed.

Just using the basic 4-band design, it seemed to have quite good SWR
dips, and responded to tuning. It did not have your problem. It does
use whips like (or close to) the ones in the article, not true Hamsticks.

However, I kept trying to add Ten Meters. By changing one of the ground
elements to a hot element, and adding two 45 degree upward-tilted
grounded elements on a bracket, I was able to "share" one of the
dipoles. If one band's hot element is on the north end, then its
grounded element is the southern 45 degree element, and vice-versa for
the second band.

I tried various pairings of Ten, Fifteen and Twenty, but there was
always one band of the two that suffered with either a poor SWR dip
and/or a center frequency shifted downward. I ended up sharing Fifteen
and Ten Meters, with Ten Meters being the band that suffered. Even with
a poor dip, the SWR is below 2:1 over the entire Ten Meter band.

So far, Ten Meters is the only band I've gotten signal reports on, and
only for local contacts. In that situation, it seems to compare
favorably to a mobile installation with a single whip.

Fred
K4DII