Diversity receive versus QRM eliminators

[Dick Dickinson]

This is a topic that interests me.  I have a wrinkle to add.

 

Qualifications:  I am a generalist rag-chew HF phone operator / listener.
I'm not seeking rare DX nor exploring weak signals in general nor a
competitive operator.

 

I'm currently running K3(-s) with a DXE NCC-2 and a 2 x 6 remote antenna
switch.  I also have an MFJ-1026 but have not done A / B testing comparing
the 2 units.  The 2 x 6 remote antenna switch allows me to select any of 6
for the Main / TX antenna and any of the 5 remaining as the RX / Noise
antenna.  

 

Now to the wrinkle.  Antenna modeling has shown me that Inverted Vee
antennas favor Vertical Polarization off the ends and Horizontal
Polarization on the broadsides.  I have two Inverted Vees up for 40 meters.
The apex of each is about 38'.  They are a nominal quarter wavelength apart
in spacing AND orthogonal to each other.  That gives me the opportunity to
take some advantage of polarization per direction / selection of antenna.

 

In any event, that's the setup.  I don't presently have any great findings
to share.  At it simplest, I can select one or the other singly to lessen
noise bidirectionally.  The noise canceling unit isn't necessary for
that.just the difference in polarization of the two antennas used singly can
be helpful.  The orthogonal antennas do give me an additional variable to
utilize as far as noise diminishing / signal enhancing.

 

I've not had all this together for too long.  I'm hoping the setup with
various antennas will prove effective in many circumstances.  I believe I
have demonstrated that to my general satisfaction.  Sometimes I've been able
to bring out an otherwise unheard side of a QSO by adjusting.  SSB is tricky
to gauge Signal to Noise Ratio with signals jumping up and down as well as
background noises such at lighting intervening.  A visual display such as a
spectrum scope helps, especially with overall background noise.

 

People familiar with operating Noise Canceling units may suggest that there
is little automatic about them.  It often takes some work.  If you have a
single source noise and an appropriate antenna setup, they can be quite
effective.  Many think that antennas 'should be' as alike as possible in
orientation and phase.  Others offer differing viewpoints.

 

I couple of times I have read that an Antenna Noise Canceling unit 'cannot'
take out lightning static.  In some circumstances I have been able to
substantially diminish lightning static from beyond the horizon for a
much-improved S/N ratio.  It is not easy and far from for sure with any
lightning storm but on some occasions, it can be done.

 

 

Digitization of some aspects of Antenna Noise Canceling is hopefully not too
far out in time.  Direction determination with stationary (and unswitched)
antennas.a great bonus should that happen.

 

 

As ever,

Dick - KA5KKT

 

 

 

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