Jan, Rik, MF,
I have made some measurements and observations:
When using the active E field antenna while having the transmit antenna
in resonance, the signal levels are 10 dB higher then with a
de-resonated antenna. So there is definitely a coupling between then.
HOWEVER the S/N is much better when the transmit antenna is out of
resonance. This can clearly be heared because i'm using a medium fast
AGC now (USR file of my last mail), so the lower audio levels become
compensated. But the QRN is very clearly louder than the background
noise. So there is a receive improvement (in this location) when the
transmit antenna is out of resonance! Now, the higher local QRM could be
produced in the first amp stage of the active antenna or is could come
from the transmit antenna itselfe. So i have connected the receiver to
the transmit antenna and used a switchable attenuator in series and set
about to the same signal level. The RX and netbook was running on
batteries during the test. When comparing these results (small active E
field antenna versus large transmit antenna) the S/N (e.g. of IQ2MI) of
the small antenna is clearly higher! In other words, the MF earth seems
to be contaminated by QRM!
That means my receive sensitivity is another important step better than
a few days ago...
73, Stefan/DK7FC
Am 20.06.2012 02:17, schrieb pa3abk:
Stefan,
Just be sure that the TX antenna is not coupled to the E-probe. (
De-tune the system when you check it)
I'm mostly listening on my TX antenna, the E-probe is only a few
meters away. These two interact in such that the E-probe is just a
bufferamp of the main aerial.
To give you an idea how heavy this is: With a portable (AWP20 AKAI) I
can enjoy MF in the toilet and bathroom providing the radio is near
the waterworks and TX aerial is tuned.
IQ2MI is "good" beacon, just before sunset it manifest itself here and
build up to S-6 during midnight. During the winter you can enjoy it
the whole day.
I
FYI sometimes during clubevenings (Tuesdays?) it comes "live" with
CQ. But assume they will not listen on 477 :-(
Checked Meteox, during our QSO a heavy thunderstorm was over your QTH,
it moved away and lost a lot of it's activity.
Just to advise you that you shouldn't misinterpret your observations.
Jan/pa3abk
NNNN
On 20-6-2012 1:29, Stefan Schäfer wrote:
MF,
I took the QRSS/CW beacon signal from IQ2MI as the test signal. It
was very well audible here, R5. It was interesting to see the deep
QSB. Both, my small active antenna and the transmit antenna show the
same S/N but maybe it would be useful to use a antenna switch to
compare the S/N without having a time delay (changing the antenna
cables), due to the QSB...
73s..
Am 20.06.2012 00:44, schrieb Stefan Schäfer:
Rik, MF,
Right now i'm testing the TX antenna as a RX antenna. This works
much better than expected. A 10 dB attenuator is needed but no
problem. Maybe you can give me a test signal again on 502 kHz, or
someone else?
It looks like the QRN is much lower on that antenna. That means that
many of the crashes during my CQ calls have been charged rain drops
that were falling on the E field probe, just my guess.
I will listen another 20 min. on 502 kHz and apprechiate any test
signals from amateurs.
73, Stefan
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