I want to build a home made omni for use on tower.

I want to feed it with coax and have lot of wire, copper pipe, tubing, basic
parts.

I have a pretty good tuner and will use the tuner to tune. Can anyone make a
recommendation as to how to make a not so complicated omni directional
antenna that practical?

I am thinking something about 6 to 10 foot in height only, I can make gnd
planes, but something I can tune to get most bands and simply omni function.
I want to get all bands and I run barefoot and just want to get on the air
with simplest, least complicated, easiest to build omni. I don't need a
electronics lesson in engineering design, just a website or two explaining
the simple build of the magical omni fed with coax that is the best I can
get for my situation.

Thanks

73s

On 9/24/2012 7:20 AM, Tom wrote:
I want to build a home made omni for use on tower.

I want to feed it with coax and have lot of wire, copper pipe, tubing,
basic parts.

I have a pretty good tuner and will use the tuner to tune. Can anyone
make a recommendation as to how to make a not so complicated omni
directional antenna that practical?

I am thinking something about 6 to 10 foot in height only, I can make
gnd planes, but something I can tune to get most bands and simply omni
function. I want to get all bands and I run barefoot and just want to
get on the air with simplest, least complicated, easiest to build omni.
I don't need a electronics lesson in engineering design, just a website
or two explaining the simple build of the magical omni fed with coax
that is the best I can get for my situation.

Thanks

73s


Use the tower!

KD7HB

You have set yourself up for quite a challenge! Limiting yourself to a length of "6 to 10 feet" is going to be a problem. At ten feet you'll be more-or-less resonant on 10 and 12 meters, and will be able to use the tuner for 15m and (maybe) 20.

Even much longer antennas don't work all bands, although some use coils to improve coverage.

In short, a shorty antenna will not work well on all bands. If you have room, you'd be better off with separate verticals for each of the bands you want to use.

I thought of that but there are a bunch of other things on there like TV
antennas, dishes, clothes lines, back yard lights, etc etc. Stunt it, just
wanted to throw up a crazy idea, I know it is a very broad question. What is
the smallest thing I could use with a pretty good tuner? On top the utility
tower?



"Paul Drahn" wrote in message
...
On 9/24/2012 7:20 AM, Tom wrote:
I want to build a home made omni for use on tower.

I want to feed it with coax and have lot of wire, copper pipe, tubing,
basic parts.

I have a pretty good tuner and will use the tuner to tune. Can anyone
make a recommendation as to how to make a not so complicated omni
directional antenna that practical?

I am thinking something about 6 to 10 foot in height only, I can make
gnd planes, but something I can tune to get most bands and simply omni
function. I want to get all bands and I run barefoot and just want to
get on the air with simplest, least complicated, easiest to build omni.
I don't need a electronics lesson in engineering design, just a website
or two explaining the simple build of the magical omni fed with coax
that is the best I can get for my situation.

Thanks

73s


Use the tower!

KD7HB

I thought of that but there are a bunch of other things on there like TV
antennas, dishes, clothes lines, back yard lights, etc etc. Stunt it, just
wanted to throw up a crazy idea, I know it is a very broad question. What is
the smallest thing I could use with a pretty good tuner? On top the utility
tower?

How about a car/truck "screwdriver" antenna?

I have a pretty good tuner and will use the tuner to tune.

The combination of a short vertical, a tuner in the shack, and a coax
feed, is not a particularly happy one.

You *may* be able to tune it, in the sense of presenting a load to
your transceiver which won't cause its output section to complain or
leak blue smoke. However, the losses in the tuner, and (particularly)
in the coax feedline, are likely to be very high... you won't get
much signal out, and you may end up with high enough voltages on some
sections of your coaxial feedline to cause arcing (even at "barefoot"
power levels!)

So, the two approaches I can think of which might work would be:

(1) A "screwdriver" antenna or equivalent... a vertical whip (longer
is better) and a remotely-adjustable loading coil.

(2) A vertical whip, and a remote-controlled (or self-controlled)
antenna tuner / transmatch mounted right at the base of the whip.

In either case, you'll probably need to use the tower itself as the
"ground" (counterpoise) for the tuned antenna... plan on running some
heavy, low-impedance braid from the tuner to the antenna mount point.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

"Tom" wrote in message ...

# I thought of that but there are a bunch of other things on there like TV
# antennas, dishes, clothes lines, back yard lights, etc etc. Stunt it, just
# wanted to throw up a crazy idea, I know it is a very broad question. What
is
# the smallest thing I could use with a pretty good tuner? On top the
utility
# tower?

With an antenna that short, you will need a ground for it to work against.
If you can manage that with guy wires etc., let me relate my recent
experience.

I use a vertical mounted above a metal patio cover, which is about 15x30
feet, roughly 10 feet off the ground. The feedline is 15 feet of RG8 to a
tuner.

Initially, I installed a 9 foot CB whip antenna. It worked quite well on 12
and 10 meters. 17 and 15 meters were hard to match, and marginal contacts
were made on 20 meters.

I replaced that whip with a 14 foot whip. It worked quite well on 20 meters
through 10 meters. I was quite happy with it, but got the bug to experiment
some more.

lastly, I replaced the whip with a 17 foot whip. It works well on 30 meters
through 15 meters, and can be brute force loaded on 40 meters through 10
meters. I don't have much performance info, since the bands have been
stinko for a while.

Both the 9 foot whip and the 14 foot whip did a credible job during the last
set of DX contests, with the 14 foot clearly being better.

In summary, if the antenna is 8-10 feet, I wouldn't count on getting much
performance other than on the higher bands, say 15-10.

On 9/24/2012 9:20 AM, Tom wrote:
I want to build a home made omni for use on tower.

I want to feed it with coax and have lot of wire, copper pipe, tubing,
basic parts.

I have a pretty good tuner and will use the tuner to tune. Can anyone
make a recommendation as to how to make a not so complicated omni
directional antenna that practical?

I am thinking something about 6 to 10 foot in height only, I can make
gnd planes, but something I can tune to get most bands and simply omni
function. I want to get all bands and I run barefoot and just want to
get on the air with simplest, least complicated, easiest to build omni.
I don't need a electronics lesson in engineering design, just a website
or two explaining the simple build of the magical omni fed with coax
that is the best I can get for my situation.

Thanks

73s

Have you chosen a frequency you might want to use? That's kind of
important.

tom
K0TAR

On Monday, September 24, 2012 8:34:09 PM UTC-5, tom wrote:
Have you chosen a frequency you might want to use? That's kind of
important.

I was wondering the same thing. There's a lot of difference between antennas for 4 MHz and 440 MHz.
--
73, Cecil, w5dxp.com

Hi
Thanks for all the info and advice and ideas.

I have the 102 foot dipole up there now, my problem is I just put a TV
antenna HD (two 8 bay bow tie Channelmaster) antennas right above the
dipole's center point (about 1 meter away) and now I am having difficulty
tuning that dipole for anyband. In fact if I try too long the old 1970
transceiver shuts off automatically and scares me that I may have some of
that blue smoke you talked about. So I wanted to get something above it,
omni that would work as well as the dipole did work. Something simple, and
easy becuase nothing up there on the top now.

I think as you folks mentioned the omni fed with coax at short lengths will
be difficult unless it is long enough and with gnd planes, but first wind
storm will bring it down.

I will focus back onto the dipole. Do you think it is too close to the new
TV antennas? Would that cause the innability to tune it where I was able to
before through the manual tuner?

What would be a suitable distance from the center point of that dipole to be
away from anything that would cause such innability to tune. Right now I am
thinking one of the legs of the dipole are fractured and that is the
problem. I don't have a way to test each leg of the dipole, it is about 50
feet of ladder line and then each leg but how do you test from the shack if
there is a fracture without the fancy scopes that you guys have? Other than
bringing each leg down and using ohm meter from one end to the other.

Any comments about having those channel master HD antennas too close to the
center feed point of a dipole? And the havok it can do to an old transceiver
and tuner?

Thanks

73s












"W5DXP" wrote in message
...
On Monday, September 24, 2012 8:34:09 PM UTC-5, tom wrote:
Have you chosen a frequency you might want to use? That's kind of
important.

I was wondering the same thing. There's a lot of difference between
antennas for 4 MHz and 440 MHz.
--
73, Cecil, w5dxp.com

I doubt the TV antenna is affecting the dipole. You may have broken the
dipole or feed line when you put up the TV antenna.

Also check to see that you did not put the TV feedline too close to the
dipole feedline. It should be atleast a foot or more from it..


"Tom" wrote in message
...
Hi
Thanks for all the info and advice and ideas.

I have the 102 foot dipole up there now, my problem is I just put a TV
antenna HD (two 8 bay bow tie Channelmaster) antennas right above the
dipole's center point (about 1 meter away) and now I am having difficulty
tuning that dipole for anyband. In fact if I try too long the old 1970
transceiver shuts off automatically and scares me that I may have some of
that blue smoke you talked about. So I wanted to get something above it,
omni that would work as well as the dipole did work. Something simple, and
easy becuase nothing up there on the top now.

I think as you folks mentioned the omni fed with coax at short lengths
will be difficult unless it is long enough and with gnd planes, but first
wind storm will bring it down.

I will focus back onto the dipole. Do you think it is too close to the new
TV antennas? Would that cause the innability to tune it where I was able
to before through the manual tuner?

What would be a suitable distance from the center point of that dipole to
be away from anything that would cause such innability to tune. Right now
I am thinking one of the legs of the dipole are fractured and that is the
problem. I don't have a way to test each leg of the dipole, it is about 50
feet of ladder line and then each leg but how do you test from the shack
if there is a fracture without the fancy scopes that you guys have? Other
than bringing each leg down and using ohm meter from one end to the other.

Any comments about having those channel master HD antennas too close to
the center feed point of a dipole? And the havok it can do to an old
transceiver and tuner?

Thanks

73s