Message-ID: <4FE25A8B.6000403@iup.uni-heidelberg.de>
Date: Thu, 21 Jun 2012 01:19:39 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
References: <4FE0ED02.4080903@iup.uni-heidelberg.de>,<4FE0EF87.8060905@kpnmail.nl> <7E7DFBB4D102A04DB5ADC88D66628A4A0FAB195C@ICTS-S-MBX5.luna.kuleuven.be> <4FE100DB.60809@iup.uni-heidelberg.de> <4FE10B61.7060202@iup.uni-heidelberg.de> <4FE116B4.4080401@kpnmail.nl>
In-Reply-To: <4FE116B4.4080401@kpnmail.nl>
Subject: Re: LF: Test signal needed, observations...
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: quoted-printable
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
X-AOL-SCOLL-URL_COUNT: 0  
x-aol-sid: 3039ac1d40c94fe25b22785e
X-AOL-IP: 195.171.43.25
X-AOL-SPF: domain : blacksheep.org SPF : none


Jan, Rik, MF,

I have made some measurements and observations:

When using the active E field antenna while having the transmit antenna=20
in resonance, the signal levels are 10 dB higher then with a=20
de-resonated antenna. So there is definitely a coupling between then.=20
HOWEVER the S/N is much better when the transmit antenna is out of=20
resonance. This can clearly be heared because i'm using a medium fast=20
AGC now (USR file of my last mail), so the lower audio levels become=20
compensated. But the QRN is very clearly louder than the background=20
noise. So there is a receive improvement (in this location) when the=20
transmit antenna is out of resonance! Now, the higher local QRM could be=20
produced in the first amp stage of the active antenna or is could come=20
from the transmit antenna itselfe. So i have connected the receiver to=20
the transmit antenna and used a switchable attenuator in series and set=20
about to the same signal level. The RX and netbook was running on=20
batteries during the test. When comparing these results (small active E=20
field antenna versus large transmit antenna) the S/N (e.g. of IQ2MI) of=20
the small antenna is clearly higher! In other words, the MF earth seems=20
to be contaminated by QRM!

That means my receive sensitivity is another important step better than=20
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. (=20
> De-tune the system when you check it)
> I'm mostly listening on my TX antenna, the E-probe is only a few=20
> meters away. These two interact in such that the E-probe is just a=20
> bufferamp of the main aerial.
>
> To give you an idea how  heavy this is: With a portable (AWP20 AKAI) I=20
> can enjoy MF in the toilet and bathroom providing the radio is near=20
> the waterworks and  TX aerial is tuned.
>
> IQ2MI is "good" beacon, just before sunset it manifest itself here and=20
> build up to S-6 during midnight. During the winter you can enjoy it=20
> the whole day.
> I
> FYI sometimes during clubevenings  (Tuesdays?) it comes "live" with=20
> CQ. But assume they will not listen on 477 :-(
>
> Checked Meteox, during our QSO a heavy thunderstorm was over your QTH,=20
> 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 Sch=E4fer wrote:
>> MF,
>>
>> I took the QRSS/CW beacon signal from IQ2MI as the test signal. It=20
>> was very well audible here, R5. It was interesting to see the deep=20
>> QSB. Both, my small active antenna and the transmit antenna show the=20
>> same S/N but maybe it would be useful to use a antenna switch to=20
>> compare the S/N without having a time delay (changing the antenna=20
>> cables), due to the QSB...
>>
>> 73s..
>>
>> Am 20.06.2012 00:44, schrieb Stefan Sch=E4fer:
>>> Rik, MF,
>>>
>>> Right now i'm testing the TX antenna as a RX antenna. This works=20
>>> much better than expected. A 10 dB attenuator is needed but no=20
>>> problem. Maybe you can give me a test signal again on 502 kHz, or=20
>>> someone else?
>>>
>>> It looks like the QRN is much lower on that antenna. That means that=20
>>> many of the crashes during my CQ calls have been charged rain drops=20
>>> that were falling on the E field probe, just my guess.
>>>
>>> I will listen another 20 min. on 502 kHz and apprechiate any test=20
>>> signals from amateurs.
>>>
>>> 73, Stefan
>>>
>>>
>>
>>
>
>