Message-ID: <379690E9.EBAA9D13@netins.net>
Date: Wed, 21 Jul 1999 20:32:57 -0700
From: "Doc Gruis" <donnatom@netins.net>
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To: rsgb_lf_group@blacksheep.org
Subject: LF: De-tuned antenna
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I really don't know if there is the practice in Europe of
directional AM broadcast stations, i.e., 540 to 1600 (or 1700) KHz., but
it sure is practiced here in the U.S.  

     The mention was made of the foliage growth close to the feed line,
etc.  Here are a couple of many instances of natures messing up an
antenna system.  Well, maybe three...)

     1.  One station I worked at was on 1390 KHz. and had a four tower
array and the tower field was surrounded by corn fields and even though
they were over a hundred feet away at the closest point, the radiation
pattern of the station was altered and so was the impedance's, tuning,
phase, etc., of the towers.

     2.  I worked at another 4 tower station on 1360 and for no apparent
reason the whole array would go in and out of tune and specifications. 
Then one evening, I spotted a field mouse in the tuning house and found
nests built inside the lighting isolation transformers or coils,
whichever they happened to have.  The little mice must have thought it
very warm due to R-F heating.

     3.  And it seems like last winter someone on this list was talking
about ice formation and that is enough said.

     SO if the tuning is that sensitive at a frequency about ten times
your 136 KHz. band, it must be devastating at the long waves!

     I certainly enjoy the postings to this list.  Thank you very much! 
AND your home pages are very good indeed.

     I have a 1 watt beacon operating on 175 KHz. and will be putting up
a new antenna this autumn.  My efforts must be modest since our lot is a
rather conventional 50 X 150'.

73!

Doc, K0HTF and long wave "D"