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Re: LF: 8.97kHz - Near field test by ear: The "human factor"

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Subject: Re: LF: 8.97kHz - Near field test by ear: The "human factor"
From: "Mike.WE0H" <[email protected]>
Date: Fri, 28 May 2010 12:04:14 -0500
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We all started in tiny baby steps in life. It goes the same with successful radio experiments. Start out with small experiments and that can grow to larger experiments. You EU guys are the pioneers of the 8kc band.

Mike
WE0H


Horst S wrote:
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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