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Old March 29th 17, 01:26 PM posted to rec.radio.shortwave
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Default Semi-related: FM Dipole Total Length

In article , writes:
George Cornelius wrote: "Note that the feed line is _not_ part of the antenna. "

That's what I always thought, so I
figured it's length(height) did not
matter. I think I'm just wayyyy
over-complicating this matter, and
should go with a simple zip-cord
dipole. Like I said, the old one
worked great, even with one half
broken off and tied around the
feed line. It was even pulling in
stations when it was detached from
the stereo receiver and sitting
in a pile in the corner!


Actually, any metal nearby will affect reception,
so that isn't such an odd statement as it sounds.

But, anyway, thanks for sending me a jpeg. I had it
all wrong in my head about how you were set up, and,
yes, with your F-connector to screw terminal balun
plugged directly onto the connector at the back of
the set you would have a pure vanilla installation
for twinlead and, if a-d is right, with about 1/2
wavelength - say five feet - of parallel feedline,
300 ohm or not, to the antenna, then we may be
able to rule out feed line as an issue and that
leaves the antenna. Shortest path between two
points: put another balun at the far end, tie it
to two 2.5" lengths of ordinary wire, and use
five feet of the speaker wire feed line between
them. You can always figure out how to drop the
baluns and use coax later on. Or to beg borrow
or steal five feet of twinlead from someone.

As I mentioned privately, I have the following old
commercially made FM dipole and am willing to ship it
to you:

64" end-to-end
70" feed line
1.75 oz weight by my little handheld postal scale balance

George
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Old March 29th 17, 01:37 PM posted to rec.radio.shortwave
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Default Semi-related: FM Dipole Total Length

In article , (George Cornelius) writes:
tie it
to two 2.5" lengths of ordinary wire,


Oops! 2.5 _feet_ on each side.
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Old March 29th 17, 04:00 PM posted to rec.radio.shortwave
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Default Semi-related: FM Dipole Total Length

George Cornelius wrote: "Oops! 2.5 _feet_ on each side. "

30". My first dipole was about that
length per side. Got in only the upper
half of the band. Once I got up past
35" per side, I started getting in
stations below 97 FM.

Now I'm up to 80" total, and I get the
whole band in, but moderate static
throughout.
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Old April 2nd 17, 04:32 AM posted to rec.radio.shortwave
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First recorded activity by RadioBanter: Sep 2012
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Default Semi-related: FM Dipole Total Length

In article , writes:

30". My first dipole was about that
length per side. Got in only the upper
half of the band. Once I got up past
35" per side, I started getting in
stations below 97 FM.

Now I'm up to 80" total, and I get the
whole band in, but moderate static
throughout.


Oh, if both antennas behave the same way
then we have to look somewhere else for
the discrepancy.

And you can be sure there is one, or we
have done something astounding: we will
have overturned 100 years of experience
with building dipole antennas.

I found two more commercially made FM
dipoles today, and of course they are
all roughly the same length. One was
tacked to a piece of plastic trim -
basically quarter round - and behind my
old Harmon Kardon 330B receiver, which
I no longer use.

Attaching the antenna and moving the
speakers over from some other sound
system I had been trying out, I fired
it up, and what I found was:

o The public radio station at 91.7 I
had been having trouble with on the
other side of town, and closer to
the tower, came booming in and
read 8 points on the signal strength
meter. So low end of the band was
OK.

o Major stations both at low end and
high end of the band came in at roughly
the same reading.

o Did not go into further detail, say
with more distant stations, but from
just a few minutes of testing, the
standard dipole design is working like
a charm with no preference for any
particular part of the band.

I would start looking for problems at
your receiver end, and if that is not
the problem, put the commercial dipole
outside, into a 4:1 xformer, and use
ordinary CATV coax to feed back into the
house and into your F connector.

I expect that one or the other of these
will tell the story.

George
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