Hello dreamers
Unbelievable: 400m at by ear reception with only 4 Watt and a small
earth base? At my QTH at city environment my 30m earth base at about 300
W did not work. At my T-antenna the 300 W were just good for only 100
meters.
Of course one limiting factor still is the influence of trees and buildings.
But what is the influence of the different frequencies used? I did my
tests around 8.9 kHz. Now I reproduced them with 1 kHz but the
audibility did not improve. I testet the other frequencies in 1kHz steps
up to 8.9 kHz with the same results. So I am sure that I hear more ore
less linear in that frequency range. So the different frequencies can
not be the reason for my lower "ODX".
In the next step I tried to hear not a single frequency but a 1 kHz
stepped sweep signal between 2 and 8.9 kHz and later a DFCW signal 2.5
and 3 kHz. The sweep signal was clearly audible at more than double the
range. My "ODX" increased to nearly 300 Meters just by ear.
The effect seems to be more psychological. I heard the stepped sweep
signal much better than its single frequencies.
Could it improve the audibility to go from A1 to A2 by just modulating
the carrier with an other? I assume an oscillator like XR2206 is not
stable enough but possibly worth a try.
Possibly anybody knows a software that achieves creating a testfile.
But this is not of priority.
Tomorrow I'll do another near field test with an eField antenna at my
roof top.
One can discuss sense or nonsense of this walk around tests. To me it's fun.
Of course other more DX related (OK, I hope so.) tests will follow
within the next weeks. Yesterday I conducted most of my material for the
earth base test coming soon. The most important: about 800m crude wire
are now on a reel. I don't know how often I crossed the soccer field in
my neighbourhood . . .
vy73 Horst DO1KHS/DI2AN
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