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LF: Re: Re: A help with rx sensitivity ??

To: "LF-Group" <[email protected]>
Subject: LF: Re: Re: A help with rx sensitivity ??
From: "Dick Rollema" <[email protected]>
Date: Thu, 22 Jul 1999 12:02:14 +0200
Reply-to: [email protected]
Sender: <[email protected]>
From PA0SE

Geri, DK8KW, wrote:

I am probably the closest amateur-LF station to DCF39, so my
measurment is not relevant. I receive it here constantly -33 dBm(75) with
my new "Umbrella-Type Antenna", about 120 km away from the transmitter
site.

Dear Geri,

I am a bit amazed that the signal is "only" -33 dBm because at my QTH the
signal has exactly the same strength but I am 500 km from DCF39!
I use a Wandell & Goltermann PSM-5 Pegelmessplatz.

According to CCIR graphs for "Land" (sigma = 30 mS/m, epsilon = 40)  the
signal at your place should be some 18 dB stronger than with me.

Maybe the ground between DCF39 and my QTH is better, propagation wise
speaking, than between DCF39 and your QTH.

I read your are using  a new antenna. Did you also pay attention to the
earthing system? It is in this part of the system that invariably the
greatest
losses occur.

The situation at my place seems to be not too bad, going by the reports I
receive.

I earthed the rig to the central heating system and that is connected via
the gaspipe to real ground.

Total resistance is about 60 ohm, of which  some 48 ohm is loss in the
earthing system and 12 ohm in the loading coil (L = 3,3 microhenry).


I had a look at your website with the conversion table for dBm, dB and
S-points. Very useful indeed!

Hope we can have a QSO in the near future.

73, Dick, PA0SE




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