Hello Horst!
My last mail was written in the afternoon but was reflected just before some
minutes :-/
You already have been out and got good results, very fine! I am interested in
your 800m long wire results :-) Do you have some more power for that test?
I also did some transmission tests within the near field, using about up to 40W
into a 25m long wire in about 15m height. I transmitted withh the TV
transformer in a distance of 1,8km. But it was in a wet forest and i had a bad
earth and the transformer was not resonated and i had no measurement devices
with. There was no reception in this first test, not even in DFCW-600. I will
do it again with a better equipment but it seems that this region is very
lossy! Maybe i should try another antenna here! If you reach 0,4km BY EAR with
QRP i should reach the grabber with QRO and DFCW-600 out of 1,8km with a
suitable wire ;-). Maybe i should also try such a earth antenna tomorrow. The
VFO and PA is available. Today, after my transmission the car battery was to
weak to start the engine so i had to roll the car a litte up on the top of the
hill to roll down on the other side and start the engine. Exciting, in the
darkness ;-)
Horst, what is the impedance of your earth pole antenna? What is the antenna
current and the antenna dimensions? My 300W PA can apply up to 100V at its
output (in abt 12V steps). I still have no imaginations what i need for that :-)
Good luck with the following tests!
73, Stefan
Now sending this mail at 22:17 UTC!
________________________________
Von: [email protected] im Auftrag von Horst Stöcker
Gesendet: Fr 28.05.2010 18:11
An: [email protected]
Betreff: LF: 8.97kHz - Near field test by ear: The "human factor"
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
NEU: WEB.DE DSL für 19,99 EUR/mtl. und ohne Mindest-Laufzeit!
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