Message-ID: <20090820170908.8hjj1qmrwo04kck0@webmail6.kuleuven.be>
Date: Thu, 20 Aug 2009 17:09:08 +0200
From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: Re: Tree noise
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Mike,

I am a bit sceptic about "bio-electric noise".
If a tree turns out to be a noise source I might be more likely that =20
it acts as a (very poor) antenna that picks up signals and re-radiates =20
them.
My major trouble with trees is that they increase losses if they are =20
close to the transmitting antenna. I can confirm that losses drop =20
considerable if the temperature goes down.
My 500kHz antenna is surrounded by many hundreds of trees, resulting =20
in a loss resistance of 30 Ohm in winter and 70 Ohm in early summer =20
(now - mid august - it has dropped to 60 Ohm).
But I have a very low noise level, mainly due to the fact that apart =20
from my own house all other QRM sources are at least 70m away. The =20
real QRM culprits such as street lights and overland power lines are =20
150m (first street light) up to 250m (first overland power line) away.

73, Rik  ON7YD
Quoting Mike Underhill <mike@underhill.co.uk>:

> Dennis (DL6NVC)
> Please could you try your loop away from the tree.  Preferably more than=
 2
> metres.  I have found severe bio-electric(?) noise from trees from 3.5=
 to
> 500MHz.using loops, whips and UHF Yagis.  The noise drops to almost zero=
 if
> the tree ambient temperature is below about zero Celsius.
> Mike - G3LHZ
>
> ----- Original Message -----
> From: "Dennis" <Dennis.Hennig@gmx.de>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Wednesday, August 19, 2009 2:03 PM
> Subject: LF: Re: 500kHz qrg range* THANKS!
>
>
>>
>>> 2. Most of the time there is a terrible broadband noise present in my
>>> home location, which blocks everything below 14MHz and even degrades
>>> Polskie Radio I on 225kHz and BBC4 198kHz (with the rx loop outside th=
e
>>> house in a tree). That's the reason why I did not report any reception=
 on
>>> 500kHz in the last weeks. There simply wasn't anything to receive...
>>> Although in a few kHz bandwidth this broadband noise of course does no=
t
>>> equal the fieldstrengh of a local broadcast station, the broader the
>>> filter, the higher the level, unneccesary loading the mixer.
>>
>> vy73
>> Dennis
>> DL6NVC
>>
>>
>>
>>
>>
>>
>>
>>
>> --
>> Neu: GMX Doppel-FLAT mit Internet-Flatrate + Telefon-Flatrate
>> f=FCr nur 19,99 Euro/mtl.!* http://portal.gmx.net/de/go/dsl02
>>
>>
>
>
>