Hello Roger,
Below you find my eport on the todays LF earth antennas test. Currently
it seems not possible for me to send to the reflector. I even do not
get mails from there... (?)
Markus/DF6NM has forwarded the mail to the reflector but it wasn't
reflected. Maybe, you can try to forward it? Can you tell me if it was
reflected?
The mail contains some infos about my todays activity on VLF/LF! So
could be interesting to some RX stations :-)
Best 73, Stefan/DK7FC
-------- Original-Nachricht --------
Hello Marco, Michel, John, LF,
This is a great day for the optimists, regarding
EARTH ANTENNAs as
a TX antenna! :-)
Until today i have not spend too much attention to my earth antenna as
a TX antenna on LF. But knowing that my small PA for VLF (12V/300W
class D) can also transmit on 137 kHz i gave it a first try today. I
was almost sure that my signal will be visible on my grabber in 5 km
distance but wasn't sure how the efficiency really is...
We know that the effective area of the formed loop must be smaller than
on VLF but the big advantage seems to be that the antenna is even
longer than lambda/4 for 2200m! Thus, to my surprise, and probably to
the surprise of the most of you, the antenna seems to be very suitable
as a TX antenna although the average height of the wire above ground is
just about 4m!! The ground resistance is about 600 Ohm, currently.
I am VERY happy now to have a fixed antenna in a quiet location that
does not matter of rain and wind or so and can be used from DC to HF
:-)
A first transmission at
25 W was immediately visible on the
DD7PC grabber, about
20 dB above noise in DFCW-3, distance is 77 km.
So,
it must have been audible!
A later transmission at 100 W is visible in France, with a good S/N.
Many TNX to Michel and John! If the signal was 20 dB above noise in
DFCW-3 at John's QTH in
JN17VG (436 km), it must have been
audible as well! :-)
Indeed, i have also never expected this efficiency from an earth
antenna. It is months ago that i tried to convince some people here to
try such an antenna. Maybe this day can help to convince practical
oriented people that it is worth trying things that seems to be "wasted
time" and/or "impossible" :-)))
I also hope that an earth antenna will be seen as an alternative to a
normal closed loop or a vertical, especially in a woody region.
Attached you find a screenshot of my grabber and my signal in 5 km
distance. Maybe it was 100 dB above noise? ;-)))
I still have no RX that can handle this big input signal. My 706 is not
the best idea and i have most of my LF equipment on the parents QTH but
i will try to receive tomorrow with the 706 and my PC on the earth
antenna, using some attenuators and/or transformers. I will build a
suitable RX for this antenna soon. But the QTH is EXCELLENT as you can
image :-)
So, there was a discussion about the radiation pattern of an earth
antenna, if it acts as a loop or not. Since the antenna length is in
the region a lambda, it surely will not be a pure loop and will maybe
have a preferred direction. YOU all can help to find out this radiation
pattern by listening to my transmissions that will be done in the next
days.
Tomorrow, arround 8 UTC i will do a VLF test and later a LF
test on the earth antenna. The VLF test is to reach Michael Oexner
again and later on LF i would appreciate any rprts. But still not sure
if i can come to QSO mode, due to the RX.
Now i know that this antenna is very worth to keep and improve. This
will be done in the next weeks! :-)
BTW: I cannot transmit on sunday with the kite antenna, due to
the WX, sri...
If some people want to try an earth antenna as a TX antenna, you can
ask me any questions!
Sorry, i am a little euphoric now. The best sign if this happens during
a project. Can it be wasted time then?
Best 73 and hope cuagn on LF this period!
Stefan/DK7FC
Am 24.09.2010 17:27, schrieb Michel Brunel:
Hello Marco, LF,
Excellent copy here in JN18HP, hope the capture find its way through the
reflector.
I was definitely not expecting such a signal with an earth electrode !
73
Michel - F5WK
Hello LF,
Stefan, DK7FC is transmitting with his 600m earth antenna on +/- 137.715KHz in DFCW4.
I could see him on my Grabber (see attachment)
http://www.qsl.net/dd7pc/lfgrabber_dd7pc.html and on the grabber from
Markus, DF6NM with a very good signal.
He was transmitting just with 25W and will increase now to 100W.
Any reports of his transmission are very welcome.
Vy73
Marco
DD7PC
