Thread: Pre-selectors
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Old November 18th 03, 01:04 PM
Ron Hardin
 
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RHF wrote:
So What Is Your Choices: (Why? -v- Why Not?)

[ ] Continue to use a simple Random Wire Antenna
and ADD a "Pre-Selector" to make it 'better'.

[ ] First improve your old antenna and try rebuilding/replacing
it into a "Low Noise" Antenna a la John Doty.


I'd always go to a low noise antenna; I do it myself on MW chiefly by
using pairs of outdoor active antennas combined in an ANC-4; it's low
noise because it's outdoors on buried coax, and I can steer a null on
an interference source. It works on locally-generated interference (ie.
not skywave) on any frequency, but skywave only on the low end of the
MW band. But on MW weak signals aren't much of a problem compared to
competing stations.

A broadband active loop plus a co-located active whip does the same thing
without taking any real estate, combined in and ANC-4. Its nulls are a
steerable V shape from one double-null endfire to the other, ``endfire''
being in the plane of the loop (its stand-alone maximum). With two whips
instead of a whip and a loop, endfire is in the direction of separation
of the whips (give it a quarter wave if you can) and you get the same V shape.

Lots of people use passive antennas instead of active in the same arrangement.

I don't go in much for a low-noise _single_ antenna because I'm never trying to
dig out a really weak signal, just one that's weaker than competition.

If your receiver overloads (mine doesn't) you'll have to use a preselector in any
case.
--
Ron Hardin


On the internet, nobody knows you're a jerk.