Paul,
If I were you I would ground both towers and put them 1/4 wavelength apart
on 160. Grounded towers are easily fed by using a curtain or at least a few
wires dropped from the top, distance to towers at least 1.5m. If you add
some top load wires on the towers you would come close to 1.83 MHz. It is
important to carry out the work on one tower at a time because
interaction/coupling is heavy, in the meantime detune the other tower!
This gives you on 160: omni, direction 1, direction 2.
On 80 you will have at least omni, broadside 1, and a few more depending on
how much work you put into the delaylines.
Bonuses for grounded towers are: Less risk of having problems with a direct
hit, minimized problems with high voltage build up on the tower when having
a thunderstorm close by. Easily decoupled feeders running to the rig from
impedance matching network...
GL
Len
SM7BIC
-----Ursprungligt meddelande-----
Från: Topband [mailto:topband-bounces@contesting.com] För Paul Staupe
Skickat: den 30 maj 2013 15:30
Till: topband
Ämne: Topband: Shunt fed tower plus Marconi vertical phasing on 160 and80?
I have a 90' shunt fed stick of 45G that works well on Topband with about 20
quarter wave radials.
I just obtained another 90' of 45G with a BCB tower base insulator which I'd
like to put up at the proper distance for a phased array on both 160 and 80.
I'm assuming the 1/4 wave on 160 would be about 130' which would be a half
wave on 80 and that they would have to be fed via different networks.
Has anybody done this? Does the shunt fed tower work in a phased array
situation, or would I be better off just using the insulated tower as a
Marconi single element vertical?
73,
Paul W0AD
All good topband ops know how to put up a beverage at night.
_________________
Topband Reflector
All good topband ops know how to put up a beverage at night.
_________________
Topband Reflector
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