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
it acts as a (very poor) antenna that picks up signals and re-radiates
them.
My major trouble with trees is that they increase losses if they are
close to the transmitting antenna. I can confirm that losses drop
considerable if the temperature goes down.
My 500kHz antenna is surrounded by many hundreds of trees, resulting
in a loss resistance of 30 Ohm in winter and 70 Ohm in early summer
(now - mid august - it has dropped to 60 Ohm).
But I have a very low noise level, mainly due to the fact that apart
from my own house all other QRM sources are at least 70m away. The
real QRM culprits such as street lights and overland power lines are
150m (first street light) up to 250m (first overland power line) away.
73, Rik ON7YD
Quoting Mike Underhill <[email protected]>:
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" <[email protected]>
To: <[email protected]>
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 the
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 not
equal the fieldstrengh of a local broadcast station, the broader the
filter, the higher the level, unneccesary loading the mixer.
vy73
Dennis
DL6NVC
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