Hi Bill
The resonance element reradiate noise and also the signal. If you think
about why a yagi works, all elements reradiate the signal from the driven
elements, but what about on reception, . It is the same. All resonate
elements reradiate. Any resonant structure does the same.
Here detuning the TX antenna droops the noise by 2 S units on the RX noise.
>>
So, why am I not hearing this noise many are experiencing?
<<
Noise does no add because it is incoherent, so when you remove one layer you
hear start hearing the second layer, there is always noise. But you can hear
only to predominant noise the strong one.
Detuning a tower is no easy, NX4D 90 FT vertical with top hat is insulated
from the ground, Doug was using one vacuum relay to disconnect the tower
from the feed line, Doug did it in 2007 however last year he decided to tune
a wire tapped 30 FT on the tower, the wire was there because he used to
shunt feed the tower. Doug used a capacitor to tune the wire like W8JI
explain on his website, guess what, 2 S units down on the noise floor. Now
is WF has a really deep null on the sides and RX is much better.
On Doug's case some capacitance or something was not right, end even using a
detuning relay and floating the tower was not enough to detune the
structure,
How far the tower can detune your RX antenna,? Well it is easy to see it
using EZNEC, one wave far is not enough and on 160m it is over 500ft away.
Regards
Jose Carlos
N4IS
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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