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ZS2ABF > ANTENN 25.06.08 17:54l 78 Lines 3123 Bytes #999 (0) @ WW
BID : 5A0365ZS2ABF
Read: GUEST
Subj: Re: feeding an 80 meter loop question
Path: IZ3LSV<IK2XDE<DB0RES<DB0GOS<ON0AR<HS1LMV<CX2SA<ZS0MEE<ZS0ELD
Sent: 080625/1110Z @:ZS0ELD.ELD.ZAF.AF #:5674 [5675] FBB7.01.35 alpha
From: ZS2ABF@ZS0ELD.ELD.ZAF.AF
To : ANTENN@WW
Hi antenna fans,
I have just read one of the 80Mts loop topic messages. In reply:
I built an 80 Mts loop over a year ago and have never regretted it.
It is in the form of a square. 20Mts on each leg and is 10Mts high from the
ground. Supported by 4 fibre glass, (ex Street light) poles. The insulated
wire is normal house hold "plug circuit, wiring copper wire" 5mm O/D. It is
attached at the top of the poles with nylon rope through a round insulator.
The rope is long enough to allow the Loop to be lowered, when and if required.
I feed it with 50 Ohms coax directly to the centre of one of the 20Mts sides.
At this side connection point I have inserted a home made 4:1 Balum. Made from
a piece of Ferrite rod cannibalised (Typical African) from an old short wave
portable radio.
My 3 element beam is long gone and, I have not missed it. My loop tunes from 3
Megs up to 6 meters with no problem using the internal tuner on my old Kenwood
TS450SAT.
I have done comparison tests with other hams living close by and when they get
an S7 noise level I have only S3 or there a bout's. It is a very "quiet"
aerial and requires no maintenance, except for replacing the nylon rope +-
every 3 years. I live 8 Kilometres from the sea (Indian Ocean) and here at the
coast Corrosion is normally a problem due to the high salt content in the air.
Therefore if you are considering putting up a loop, go for it you will be a
satisfied Ham.
My friend here in town is a very good Radio Technician and he also has a loop
but he has decided not too feed it with 50 ohms coax up to the 4:1 Balum. He
uses Twin feeder instead.
If you look at an article on loops in a copy of the 1990 ARRL Ham handbook it
describes the "The Loop Sky Wire" and say's do not let anyone tell you to fit
a Balum. Attach the coax and that's it !. Experiment a little and see what
suits your conditions and liking.
On my friends ladder line he can see static jumping around in bad weather. I
have seen none on mine.
The shape of the loop is not really important, so if you live in an area that
has limited space, configure the loop to fit. The idea is to have as much
space within the loop as possible. Therefore a circle is the best. The problem
then is you have to use too many poles to make a circle. So the next best is
the square. You may have a shape that is like the letter "L", then you would
have to use 6 poles to fill it on each side etc, etc.
Best 73's Peter ZS2ABF
You know the UFO guy.
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73 - Peter, ZS2ABF @ ZS0ELD
Message timed: 12:44 on 2008-Jun-25
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