Hi Doc,
Found your comments regarding effects on Medium wave broadcast
antenna systems very interesting indeed, and as you say, LF must be effected
even more by surrounding objects, considering how narrow tuned they are,
with our tiny antenna's. If I keep my present system in place until Winter
time, I will observe whether there is a gradual rise in Antenna current,
back to what it was, last Winter.
If we can get rid of Loran, on both sides of the Atlantic, perhaps we will
one day have an LF/LF qso, however a friend of mine in Canada tells me that
the Loran signal really makes a mess of reception on 136 khz, pity
really.
Best regards
Finbar EI0CF
-----Original Message-----
From: Doc Gruis <[email protected]>
To: [email protected] <[email protected]>
Date: 22 July 1999 02:56
Subject: LF: De-tuned antenna
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"
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