RadioBanter - 80 Meter Horizontal Loop

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On Tue, 7 Jun 2005 14:45:32 -0400, "Fred W4JLE"
wrote:

I will be sending you some photos of my final installation. I did a number
of tests comparing how tight you can wind the loops. I was amazed at how non
critical it was, considering all the dire warnings one receives from the old
wife's tales.

Fred, any hints on winding your 450-ohm line around the wood dowels? I
have a feedline I wouldn't mind lengthening if I could do it without
loose ladderline everywhere.

bob
k5qwg

Why bother, unless you're having a problem with the heat? 20% loss is
just about exactly 1 dB.

That's 1 db I'd rather keep to myself...Why give it away if it's
not required? If you pump up the power, heat will likely be a
problem. But saying that, I'd rather avoid the tuner altogether...
MK

On Tue, 7 Jun 2005 14:55:25 -0400, "Fred W4JLE"
wrote:

Of Course you are, all horror stories aside.

Don't confuse the angels dancing on the pinheads around here with practical
world experiences. The best solution is to increase the length of your
dipole to 130 feet and feed it with 100 foot of 450 Ohm ladderline. Connect
a piece of coax with a ferrite bead choke to the 450 Ohm line. Your tuner
will love you and you can use all bands from 80 on up.

The electrical plug on your rig has losses that are about as meaningful real
world..

Thanks for the encouragement and antenna.

I have two dipoles up right now. One is a 20 meter mono-bander that
was setup specifically for 20 meters and to test a test design for a
PVC 'cobra head' (whatever the generic name).

The other is a piece made of junk that I put up using parts I already
had available. (#14 electrical wire, PVC insulators and TV Coax). It
started as a 20 meter dipole, I added 40 and then 80 meters. It
wasn't supposed to be anything but a temporary antenna until I made a
new one, but weather, timing and money won't cooperate with me. I
have patched and patched it. Ice tore down one leg this winter and
destroyed half the PVC insulators I was using for spacers. Yesterday I
rewired the PL-259, cut the connection to the wires and re-wired it
and cut off the 40 and 20 meter elements. It tunes and hears much
better now.

I have always wanted antennas that would cover all bands without a
tuner. This was practical as a novice when all I could work was 80,
40, 15, and 10 meters. Three parallel dipoles hanging from one
antenna feed worked well. When I advanced to General, I used two
parallel dipoles and an antenna switch. (CW: 80, 40-15, 20, &10; and
SSB: 75, 40, & 10).

Today, my idea isn't as practical as it was. I now have a rig that
covers 160-6 meters on one HF connector. That's eleven bands!!
That's a lot of parallel dipoles on a feed even with the bands split
up into two antennas.

I acquired an antenna tuner recently and it tunes very quickly. I
still don't like it, but I can operate anywhere from 160-6 meters on
it (not that I have heard anyone on 6 yet.)

I would like to build a portable antenna using 300 ohm TV- twin lead
for the feed for the tuner. Is there a recommended length and feed
point for all bands?

Thanks

Buck
N4PGW

--
73 for now
Buck
N4PGW

If you would send me an e-mail so I can get your address, I will send you
some photos. Are you on broadband or dial up?

"Bob Miller" wrote in message
...
On Tue, 7 Jun 2005 14:45:32 -0400, "Fred W4JLE"
wrote:

I will be sending you some photos of my final installation. I did a
number
of tests comparing how tight you can wind the loops. I was amazed at how
non
critical it was, considering all the dire warnings one receives from the
old
wife's tales.

Fred, any hints on winding your 450-ohm line around the wood dowels? I
have a feedline I wouldn't mind lengthening if I could do it without
loose ladderline everywhere.

bob
k5qwg

I can send you a copy of a program I wrote. It is based on Cecil's work. You
can put in the length of the dipole you want to use, the frequency, and type
of feed line. It gives you the choice of giving you the length of feedline
for that single case, or a start and stop frequency in which case it prints
out a chart of frequency vs. total length.Add jumpers to make up the
difference above 80 feet and your good to go!

For portable operation a 130 foot dipole fed with 80 feet of 300 Ohm to a
small piece of Plexiglas and two sets of banana jacks would allow you to
put jumpers of various lengths into the jacks. The second set goes to the
rig via a convenient length of 50 ohm coax with a choke balun of ferrites.
Lengths of 1,2,4, and 8 foot would allow you to make up jumpers to enable 75
meters from 3.8 to 4 and all the other bands with the exception of 60
meters.

It can be made smaller if your only interested in 40 and up etc. Easy to
carry, no tuner and worst swr around 1.7:1

For example a 2 foot jumper would put you at 4.0, and a series of an 8,2,
and 1 jumper for 3.8

"Buck" wrote in message
...

I would like to build a portable antenna using 300 ohm TV- twin lead
for the feed for the tuner. Is there a recommended length and feed
point for all bands?

Thanks

Buck
N4PGW

--
73 for now
Buck
N4PGW

On Tue, 7 Jun 2005 15:51:51 +0000 (UTC), "Reg Edwards"
wrote:

If you can't get the internal SWR meter on an Icom 735 (or similar
rigs) down to exactly 1:1 then either there's something wrong with the
tuner or with the tuner operator.

The tuner either works or it doesn't. There's no half-way house.
Without a tuner anything can happen. And it usually does.

There are far too many sleepless nights unnecessarily caused by the
SWR meter not being in the right imagined ballpark. Just ask
yourselves is the transmitter loaded with roughly 50 ohms or isn't it.
The SWR on the feedline hardly matters two hoots - the so called SWR
meter doesn't measure it anyway.

Do G5RV addicts realise that under even the best conditions the SWR on
the feedline is as high as 10-to-1 regardless of what the meter says.
But it doesn't seem to worry them.
----
Reg.

I know I'll be corrected if I am wrong, but if I am correct, the SWR
is high (actually varies by band) on the feedline for the G5RV. The
twin lead portion doesn't have the losses the coax does with that SWR
so more of the signal gets to the antenna than it would if it were
just coax going to a twenty meter dipole.

--
73 for now
Buck
N4PGW

On Tue, 07 Jun 2005 15:16:47 -0500, Cecil Moore
wrote:

Wes Stewart wrote:

Cecil Moore wrote:

Fred W4JLE wrote:
All my feedlines have a 9:1 SWR by design.

Heh, heh, I understand perfectly.

You do?

Of course! The feedline Z0 equals 450 ohms. 450/9=50
Fred is using my design from:
http://www.qsl.net/w5dxp/notuner.htm

Can the 17 and 10 meter bands be tuned to a better match or are they
compromised so the antenna doesn't need additional matching sections?

--
73 for now
Buck
N4PGW

Pardon me while I learn from this discussion.

The 450 ohm antenna is designed to be tuned by using exactly 1/2
electrical wave lengths to match both the transmitter and antenna.
This should mean that any differing feedline should work equally as
well (except for the losses) if I am correct....

On Tue, 7 Jun 2005 18:02:43 -0400, "Fred W4JLE"
wrote:

I feed it with an electrical 1/2 wave length of exactly 450 Ohm feedline.
The 50 Ohms from my antenna is repeated at the other end of the feedline. An
SWR bridge calibrated for 50 Ohms and my rig see 1:1.

--
73 for now
Buck
N4PGW