I am a newbie wanting to set up a base station at my house on top of my
tv tower. I am interested in building one myself. I have the capability
to weld.

Do the j poles have gain to them? Are they near the performance of a
several element yagi?

Can I make a dual band antenna in each of these styles?

Do the copper j poles last many years? I sometimes have high winds and
lots of rain. Plus, I dont like heights and only want to do this once.

I would ideally like to reach a repeater about 70 - 80 miles away from
me.

On 2004-12-21, wrote:
I am a newbie wanting to set up a base station at my house on top of my
tv tower. I am interested in building one myself. I have the capability
to weld.


I hope you are referring to welding antenna elements, and not building a
tower by yourself


Do the j poles have gain to them? Are they near the performance of a
several element yagi?

Gain over what? Asking about gain without providing a reference point is
sort of useless. If memory serves me correct (and I do admit that my memory
is somewhat porous right now) a j-pole will have about the same gain as a
dipole over an isotropic radiator or 2.4dbi. A yagi would certainly have
more gain over a dipole or a j-pole. Remember that a yagi is directional,
and the j-pole is not. If you want to hit repeaters in more than one
direction, you will need a way to rotate the yagi.




Can I make a dual band antenna in each of these styles?


Yes, google is your friend here.


Do the copper j poles last many years? I sometimes have high winds and
lots of rain. Plus, I dont like heights and only want to do this once.


I have one that has been up for 3 years now. The only difference between now
and when it first went up is that it is a darker color now due to
weathering. It seems to be just as strong now as t was then.


I would ideally like to reach a repeater about 70 - 80 miles away from
me.

That would depend mostly on how high up you can get the antenna (yagi or
j-pole) VHF/UHF is line of sight.



--
Alex / AB2RC
Linux is user friendly, however it is not idiot friendly

AB2RC wrote:
On 2004-12-21, wrote:
I am a newbie wanting to set up a base station at my house on top
of my
tv tower. I am interested in building one myself. I have the
capability
to weld.


I hope you are referring to welding antenna elements, and not
building a
tower by yourself


Do the j poles have gain to them? Are they near the performance of
a
several element yagi?

Gain over what? Asking about gain without providing a reference point
is
sort of useless. If memory serves me correct (and I do admit that my
memory
is somewhat porous right now) a j-pole will have about the same gain
as a
dipole over an isotropic radiator or 2.4dbi. A yagi would certainly
have
more gain over a dipole or a j-pole. Remember that a yagi is
directional,
and the j-pole is not. If you want to hit repeaters in more than one
direction, you will need a way to rotate the yagi.




Can I make a dual band antenna in each of these styles?


Yes, google is your friend here.


Do the copper j poles last many years? I sometimes have high winds
and
lots of rain. Plus, I dont like heights and only want to do this
once.


I have one that has been up for 3 years now. The only difference
between now
and when it first went up is that it is a darker color now due to
weathering. It seems to be just as strong now as t was then.


I would ideally like to reach a repeater about 70 - 80 miles away
from
me.

That would depend mostly on how high up you can get the antenna (yagi
or
j-pole) VHF/UHF is line of sight.



--
Alex / AB2RC
Linux is user friendly, however it is not idiot friendly

No, the tv tower is already up. I meant I can weld the elements. (Of
course only if it is weldable material.) I was wondering if emt tubing
would be a good choice?

The antenna would be about 25 feet up. I had someone else tell me that
a j pole does not work very well. Is this true?

I can rotate the mast by turning the antenna rotor hooked to my tv down
stairs. The only pain would be running down stairs every time I want to
do it.

What would you do in this situation? Can you get as good as or better
performance building one yourself?

On 2004-12-21, wrote:

No, the tv tower is already up. I meant I can weld the elements. (Of
course only if it is weldable material.) I was wondering if emt tubing
would be a good choice?

Aluminum would be a better choice than emt tubing. The EMT stuff will rust
after a while, and is not as strong as it appears to be. It would also be
heaver than aluminum tubing for making a yagi.

You might not need to weld the tubing anyway. You can get nesting tubing,
and connect lengths by splitting the ends a bit and using hose clamps. Also
for the bands you mentioned, the tubing would more likely need to be cut to
length, rather than joined together to increase the length.



The antenna would be about 25 feet up. I had someone else tell me that
a j pole does not work very well. Is this true?


J-poles work well, but it all depends on your definiation of "working well".
The higher the better, 25 feet would probably work, but it depends on the
terrain between the repeaters and your antenna.


I can rotate the mast by turning the antenna rotor hooked to my tv down
stairs. The only pain would be running down stairs every time I want to
do it.


If you already have ther rotor that would be ok, just leave a reasonable
distance between the tv antenna (if there is still one there) and your yagi.

What would you do in this situation? Can you get as good as or better
performance building one yourself?


I think that I would put up at least 2 antennas. A j-pole first, and then a
yagi. If I had a multimode rig, I would put the yagi in a horizontal plane
for ssb use.

As for performance, you can make just about anything that the commercial
manufacturers can. It might cost more or less depending on your skills and
what you have available for materials.


--
Alex / AB2RC
Linux is user friendly, however it is not idiot friendly

On 21 Dec 2004 11:16:16 -0800, wrote:

No, the tv tower is already up. I meant I can weld the elements. (Of
course only if it is weldable material.) I was wondering if emt tubing
would be a good choice?

Hi OM,

The consensus is that it is not. If you are going to invest your time
and effort, short-cuts generally lead to repetition. You wanted to do
this once? You are in the wrong hobby. Better is how to plan doing
it many times, but planning to do it in the least stressful way.

The antenna would be about 25 feet up.

You had a range requirement of upwards to 70 miles. With a 25 foot
elevation, your mileage range is roughly the square root of twice that
- or 7 miles. You can double that if the other antenna is up equally
far. If you are on a rise of land above the mean level, add that to
your elevation. If the antenna at the other end is much higher,
compute its range (hopefully a mountain top).

I had someone else tell me that
a j pole does not work very well. Is this true?

Varies by user as it is susceptible to transmission line length
problems. These problems are SWR related. However, that aside, as a
principle antenna for the range you ask, then that antenna at the
other end has to make up for a lot (it better be higher, an array, or
some combination).

I can rotate the mast by turning the antenna rotor hooked to my tv down
stairs. The only pain would be running down stairs every time I want to
do it.

You have to now investigate if your tower/rotator can in fact stand
the additional wind load factor (or weight, or moment).

What would you do in this situation? Can you get as good as or better
performance building one yourself?

Depends on your resources. It already sounds like you are shy there
in finding aluminum of the proper grade. Best advice is to visit a
metal scrap yard in the crummy part of town. Or - bite the bullet and
pull out your wallet.

If all this is to hit a repeater, and a popular one, you should simply
try it and see what happens with a rubber duck. Then build a simple
ground plane ($5) and hoist it as high as you can (on a broomstick out
the 2nd floor window will do as a test). Popular repeaters are
popular because they solved all these problems for you (by being high
and having gain).

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On 21 Dec 2004 11:16:16 -0800, wrote:

No, the tv tower is already up. I meant I can weld the elements. (Of
course only if it is weldable material.) I was wondering if emt
tubing
would be a good choice?

Hi OM,

The consensus is that it is not. If you are going to invest your
time
and effort, short-cuts generally lead to repetition. You wanted to
do
this once? You are in the wrong hobby. Better is how to plan doing
it many times, but planning to do it in the least stressful way.

It is not I want to only do this once. It is I am a little scared of
heights and do not want to climb up that tower any more than I have to.

The antenna would be about 25 feet up.

You had a range requirement of upwards to 70 miles. With a 25 foot
elevation, your mileage range is roughly the square root of twice
that
- or 7 miles. You can double that if the other antenna is up equally
far. If you are on a rise of land above the mean level, add that to
your elevation. If the antenna at the other end is much higher,
compute its range (hopefully a mountain top).

It is a repeater 80 miles away I would like to hit. I would also to try
long range simplex if possible.

I had someone else tell me that
a j pole does not work very well. Is this true?

Varies by user as it is susceptible to transmission line length
problems. These problems are SWR related. However, that aside, as a
principle antenna for the range you ask, then that antenna at the
other end has to make up for a lot (it better be higher, an array, or
some combination).
The other problem is the transmision line will have to be long,
probably35 feet or more. Is this a problem?
I can rotate the mast by turning the antenna rotor hooked to my tv
down
stairs. The only pain would be running down stairs every time I want
to
do it.

You have to now investigate if your tower/rotator can in fact stand
the additional wind load factor (or weight, or moment).

What would you do in this situation? Can you get as good as or
better
performance building one yourself?

Depends on your resources. It already sounds like you are shy there
in finding aluminum of the proper grade. Best advice is to visit a
metal scrap yard in the crummy part of town. Or - bite the bullet
and
pull out your wallet.

If all this is to hit a repeater, and a popular one, you should
simply
try it and see what happens with a rubber duck. Then build a simple
ground plane ($5) and hoist it as high as you can (on a broomstick
out
the 2nd floor window will do as a test). Popular repeaters are
popular because they solved all these problems for you (by being high
and having gain).

73's
Richard Clark, KB7QHC

On 21 Dec 2004 13:42:56 -0800, wrote:


It is a repeater 80 miles away I would like to hit. I would also to try
long range simplex if possible.

Hi OM,

I've touched on the requirements for you and the repeater. You will
be successful in direct, root proportion to heights for simplex.

The difference between a J-Pole or Ground Plane, or vertical Dipole,
or Discone, or sleeve Dipole.... and so on, will be marginal. The
difference between a simple vertical (as were all those in that list)
and an vertical array has gain for the same power. However, the
difference between that same array compared to any antenna turned 90°
to it can have -20 to -30dB (those are minuses) difference IF you
choose the wrong orientation WRT the listener. This is called crossed
polarization and can be a killer (you wanted to put this up once, and
if that once happens to be cross polarized to the majority of the
traffic you want to engage in - kiss them good bye).

You should be advised that FM is usually vertical, and SSB is usually
horizontal. See any problems with trying to make one antenna work
everywhere?

The other problem is the transmision line will have to be long,
probably35 feet or more. Is this a problem?

Of course. You simply have to investigate by what degree. RG-174
would be like plugging your ears and mouth, other bigger and more
expensive lines would not. Fortunately this is very simple to resolve
as line is characterized in the loss per hundred feet (if you only use
35 feet, you need only reckon 35% of that quoted loss).

73's
Richard Clark, KB7QHC

On 21 Dec 2004 07:33:53 -0800, wrote:

I am a newbie wanting to set up a base station at my house on top of my
tv tower. I am interested in building one myself. I have the capability
to weld.

Do the j poles have gain to them? Are they near the performance of a
several element yagi?

Can I make a dual band antenna in each of these styles?

Do the copper j poles last many years? I sometimes have high winds and
lots of rain. Plus, I dont like heights and only want to do this once.

I would ideally like to reach a repeater about 70 - 80 miles away from
me.

For a j-pole, you might look at the Arrow Antennas site -- for one you
could purchase, or, if you're really handy with metal, you could
replicate one of their designs -- the diagrams & dimensions are all
there.

bob
k5qwg

I would ideally like to reach a repeater about 70 - 80 miles away from
me.

How many miles away don't mean much.

I have no problem reaching a repeater 100 miles away with only
5 watts & a Open Stub J-Pole. BUT, this is a big BUT.
My location in Cheyenne WY is 1000 feet higher than Denver,
and the repeater is on a mountain top 3000 feet above Denver.
That is true line of sight if you could see that far.

Now if you live in the flat lands of NE with antennas only 30 to 50 feet
high. You would be lucky to get 40 miles with 50 watts.
If you live in a valley in the mountains you may only get 4 or 5 miles.

It all comes down to Location, Location, Location.

73 Al Lowe N0IMW

Arrow Antenna

Alex wrote:
As for performance, you can make just about anything that the commercial
manufacturers can. It might cost more or less depending on your skills and
what you have available for materials.

It will also depend - a lot - on what you have available in tooling. That's
why J-poles and quagis are favorite do-it-yourself 2M antennas - you can easily
make either, and well, with typical home hand tools.
N4GSV


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