Message-ID: <20091228152259.1s7jpzyps0w40o8o@webmail6.kuleuven.be>
Date: Mon, 28 Dec 2009 15:22:59 +0100
From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
References: 	<38A51B74B884D74083D7950AD0DD85E828AD04@File-Server-HST.hst.e-technik.tu-darmstadt.de>
In-Reply-To: 	<38A51B74B884D74083D7950AD0DD85E828AD04@File-Server-HST.hst.e-technik.tu-darmstadt.de>
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Subject: Re: AW: LF: Influence of a TX antenna to a small rx antenna
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Hello Stefan,

there is a easy way to check if you have too much attenuation or not:
Tune the RX to an unused freq (only noise/QRN) and disconnect the =20
antenna; if you can hear the difference between antenna / no antenna =20
then attenuation is not too much.
With a 11m high / 25m long lazy-L antenna at a quiet location I could =20
add 40dB attenuation and still hear the noise increasing when =20
connecting the antenna.
I guess with a kite-antenna 50 to 60dB might be a good value.
Of course it all depends also on the RX used, I use a Kenwood TS440 =20
that seems to be sensitive at LF.

73, Rik  ON7YD - OR7T


Quoting Stefan Sch=E4fer <schaefer@hst.tu-darmstadt.de>:

> Hi Rik es tnx for your answer.
> In the first QSOs from /p I used the TX antenna. I quickly saw that  =20
> SNR is much better with a 6dB attenuator. In the last activity I  =20
> even used 20dB. But the SNR of the small active antenna is  =20
> definitely better. Perhaps it is a good idea to try even more  =20
> attenuation, tnx, I will try that!
> On my QTH at my parents (2003/2004) I also used the TX antenna but  =20
> it was much smaller. This antenna was more suitable for RX although  =20
> the actual QTH is apart from any house in a region of some 100s  =20
> meters...
> 73, Stefan
>
> -----Urspr=FCngliche Nachricht-----
> Von: owner-rsgb_lf_group@blacksheep.org  =20
> [mailto:owner-rsgb_lf_group@blacksheep.org] Im Auftrag von Rik Strobbe
> Gesendet: Samstag, 26. Dezember 2009 23:29
> An: rsgb_lf_group@blacksheep.org
> Betreff: Re: LF: Influence of a TX antenna to a small rx antenna
>
> Hello Stefan,
>
> why not use the "big" TX antenna also for RX. With a sufficient
> atenuator of course.
> On 137kHz I alway used my TX antenna for RX, but a 40dB attenuator was
> required to avoid overload at the RX.
>
> 73, Rik  ON7YD
>
>