On Wed, 26 Jan 2005 23:08:40 GMT, SideBand wrote:



Thanks. I am going to use LMR-400. I assume that is about the same thickness as
the RG-8.

Vinnie S.

Yes.. Roughly equivalent. What's the application? You building a dipole
or an inverted V?



Sticking a 6 foot Firestick in the attic, using eight 9' wires as a ground
plane. Then when the weather warms, I stick a Imax in a tree.

Vinnie S.

You shouldn't need a choke for that, but it won't hurt either. Keep the
plane of the coil perpendicular to the antenna (the firestik) in that
setup, and drape the wires for the ground plane over the top of it.. If
you can get a foot or two separating the coil/choke and the ground plane
wires.

-SSB


That is going to be tough. I can definitely get it under, but not by a a foot.
When you mean perpendicular, you the outer edge of the coil directly under the
antenna, king of the antenna point up at 12 o'clock at the coil? At least, that
is the way I remember perpendicular, being a vertical touching the horizontal
forming a T.

Vinnie S.

Vinnie S. wrote:
On Wed, 26 Jan 2005 23:08:40 GMT, SideBand wrote:



Thanks. I am going to use LMR-400. I assume that is about the same thickness as
the RG-8.

Vinnie S.

Yes.. Roughly equivalent. What's the application? You building a dipole
or an inverted V?



Sticking a 6 foot Firestick in the attic, using eight 9' wires as a ground
plane. Then when the weather warms, I stick a Imax in a tree.

Vinnie S.

You shouldn't need a choke for that, but it won't hurt either. Keep the
plane of the coil perpendicular to the antenna (the firestik) in that
setup, and drape the wires for the ground plane over the top of it.. If
you can get a foot or two separating the coil/choke and the ground plane
wires.

-SSB



That is going to be tough. I can definitely get it under, but not by a a foot.
When you mean perpendicular, you the outer edge of the coil directly under the
antenna, king of the antenna point up at 12 o'clock at the coil? At least, that
is the way I remember perpendicular, being a vertical touching the horizontal
forming a T.

Vinnie S.

No.. that would be parallel..

Make a circle with your forefinger and thumb. Stick your other
forefinger thru it.. That's how it should look, only not touching. If
you can't get it a foot up, get it as far up as you can, and drape the
ground plane wires over top of the coil. Not REALLY critical, but it
will help with matching.

-SSB

On Thu, 27 Jan 2005 02:56:39 GMT, SideBand wrote:


That I can do. I got 16" between the joists, and stick the coil directly under
the antenna. So if you are looking from an overhead view, the antenna is
directly in the middle of the open part of the coil. The GP wires will be over
it. Is this correct? It sounds like a plan.

Thanks for your help !






Vinnie S.

Vinnie S. wrote:
On Thu, 27 Jan 2005 02:56:39 GMT, SideBand wrote:


That I can do. I got 16" between the joists, and stick the coil directly under
the antenna. So if you are looking from an overhead view, the antenna is
directly in the middle of the open part of the coil. The GP wires will be over
it. Is this correct? It sounds like a plan.

Thanks for your help !






Vinnie S.
Yep.. you got it this time. Looking down the antenna, you're looking at
an "O" (the choke) with the antenna being the center point of the
circle. Wires physically above the coil.

Good luck.

That's what us HAMs are supposed to be here for.

-SSB

On Thu, 27 Jan 2005 05:00:04 GMT, SideBand wrote:

Vinnie S. wrote:
On Thu, 27 Jan 2005 02:56:39 GMT, SideBand wrote:


That I can do. I got 16" between the joists, and stick the coil directly under
the antenna. So if you are looking from an overhead view, the antenna is
directly in the middle of the open part of the coil. The GP wires will be over
it. Is this correct? It sounds like a plan.

Thanks for your help !






Vinnie S.
Yep.. you got it this time. Looking down the antenna, you're looking at
an "O" (the choke) with the antenna being the center point of the
circle. Wires physically above the coil.

Good luck.

That's what us HAMs are supposed to be here for.

-SSB


The PVC condiut is up. I ran a conduit so I can run the coax right to the
basement, from the attic. I will make a run tomorrow to get coax and supplies.
The Firestik arrived.

Also, I roughly measured the distance to the tree where I want to put a
permanent antenna. The distance is huge, about 275 feet of total coax. I figured
I can use LMR-400DB (direct burial). I estimate about 2 dB loss at that
distance. How much power loss is that on a HR-2510, using a Imax-2000 with a GP
kit, assuming a good SWR? I am not running power. Will that antenna offset that
loss by itself?I really don't have a choice. It's not going on the house.
Besides, the damn house is too low anyway. I can get way higher on the tree.

Vinnie S.

Vinnie S. wrote:
On Thu, 27 Jan 2005 05:00:04 GMT, SideBand wrote:


Vinnie S. wrote:

On Thu, 27 Jan 2005 02:56:39 GMT, SideBand wrote:


That I can do. I got 16" between the joists, and stick the coil directly under
the antenna. So if you are looking from an overhead view, the antenna is
directly in the middle of the open part of the coil. The GP wires will be over
it. Is this correct? It sounds like a plan.

Thanks for your help !






Vinnie S.

Yep.. you got it this time. Looking down the antenna, you're looking at
an "O" (the choke) with the antenna being the center point of the
circle. Wires physically above the coil.

Good luck.

That's what us HAMs are supposed to be here for.

-SSB



The PVC condiut is up. I ran a conduit so I can run the coax right to the
basement, from the attic. I will make a run tomorrow to get coax and supplies.
The Firestik arrived.

Also, I roughly measured the distance to the tree where I want to put a
permanent antenna. The distance is huge, about 275 feet of total coax. I figured
I can use LMR-400DB (direct burial). I estimate about 2 dB loss at that
distance. How much power loss is that on a HR-2510, using a Imax-2000 with a GP
kit, assuming a good SWR? I am not running power. Will that antenna offset that
loss by itself?I really don't have a choice. It's not going on the house.
Besides, the damn house is too low anyway. I can get way higher on the tree.

Vinnie S.

Vin:

Your loss will actually fall somewhere between 1.89 and 2dB.

2 db equates to roughly 23% power loss, assuming 1:1 SWR at the antenna.
Since 1:1 isn't easily attained (you can't get it with a resonant dipole
or a 1/4 wave whip without some sort of feed point matching, and then
you lose some radiation efficiency), you can assume you're going to get
some additional feed line (coax) losses (heating, mostly) because of
the mismatch at the antenna. For that run I would highly suggest
staying away from coax and see if you can find some 200 ohm twinlead.
Output coax from the radio to the outside to a 4:1 balun to the twinlead
to a 4:1 balun (in reverse), to about 20 feet of coax to the antenna.
Losses will be MUCH lower than with coax.

The other option would be 450 ohm twinlead (ladderline) and a 9:1 balun
at both ends. Ladderline is running about $0.19 +/- a foot, depending on
where you're getting it. The cost for the baluns and the ladderline WILL
be less than the run of LMR400.

The caveat here will be that you will need to keep the ladderline well
away from ALL metal.. within about a foot of the ladderline.

For that long of a run, I would personally run a pair of 9:1 baluns and
the 450 ohm ladderline. The cost and the losses will be lowest there.

The reason for the 25' of coax at the antenna end is to keep the
ladderline from being unbalanced by the antenna.

Estimated losses for the 9:1's and 450 ohm... .6 db (and that's at the
highest), depending on the quality of the baluns. Less than 5% power
loss, and not quite so much effect due to poor SWR at the end.

Your dipole should see about a 1.3:1 - 1.5:1 SWR across the CB band. If
it's possible to make a "V" antenna in the branches (inverted or not)
the SWR could be lower, and you could definitely see some improvements
over a vertical dipole.

HTH

-SSB

On Sat, 29 Jan 2005 03:23:53 GMT, SideBand wrote:


The PVC condiut is up. I ran a conduit so I can run the coax right to the
basement, from the attic. I will make a run tomorrow to get coax and supplies.
The Firestik arrived.

Also, I roughly measured the distance to the tree where I want to put a
permanent antenna. The distance is huge, about 275 feet of total coax. I figured
I can use LMR-400DB (direct burial). I estimate about 2 dB loss at that
distance. How much power loss is that on a HR-2510, using a Imax-2000 with a GP
kit, assuming a good SWR? I am not running power. Will that antenna offset that
loss by itself?I really don't have a choice. It's not going on the house.
Besides, the damn house is too low anyway. I can get way higher on the tree.

Vinnie S.

Vin:

Your loss will actually fall somewhere between 1.89 and 2dB.

2 db equates to roughly 23% power loss, assuming 1:1 SWR at the antenna.
Since 1:1 isn't easily attained (you can't get it with a resonant dipole
or a 1/4 wave whip without some sort of feed point matching, and then
you lose some radiation efficiency), you can assume you're going to get
some additional feed line (coax) losses (heating, mostly) because of
the mismatch at the antenna. For that run I would highly suggest
staying away from coax and see if you can find some 200 ohm twinlead.
Output coax from the radio to the outside to a 4:1 balun to the twinlead
to a 4:1 balun (in reverse), to about 20 feet of coax to the antenna.
Losses will be MUCH lower than with coax.

If I have the HR-2510 at 10 Watts DK, I am still putting out about 7.5 watts. If
I turn up the DK to about 20 watts, I can still transmit about 15.5 watts. I
guess that is not bad.

I guess the point is I can still get at least the power of a standard CB with an
antenna directly overhead.

The other option would be 450 ohm twinlead (ladderline) and a 9:1 balun
at both ends. Ladderline is running about $0.19 +/- a foot, depending on
where you're getting it. The cost for the baluns and the ladderline WILL
be less than the run of LMR400.


The caveat here will be that you will need to keep the ladderline well
away from ALL metal.. within about a foot of the ladderline.

This will be a major problem. I have all my plumbing well within a foot, across
the entire length of the house. All where I would bring the ladder line into the
house. I cannot move the entry point without some serious digging and entering
from the front of the house. There are numerous obstacles like the driveway and
sidewalk. I will have to look into the 200 ohm twin lead.

For that long of a run, I would personally run a pair of 9:1 baluns and
the 450 ohm ladderline. The cost and the losses will be lowest there.

The reason for the 25' of coax at the antenna end is to keep the
ladderline from being unbalanced by the antenna.

Estimated losses for the 9:1's and 450 ohm... .6 db (and that's at the
highest), depending on the quality of the baluns. Less than 5% power
loss, and not quite so much effect due to poor SWR at the end.



Your dipole should see about a 1.3:1 - 1.5:1 SWR across the CB band. If
it's possible to make a "V" antenna in the branches (inverted or not)
the SWR could be lower, and you could definitely see some improvements
over a vertical dipole.


In the attic, I am using a 6 foot Firestik. It is the highest I can go up there.
It is an electrical 5/8 wave, though physical 6 feet. I am using 8 pieces of 9
foot wires as a ground plane. Luckily, I have electricians in the family. This
should work OK for now?

Vinnie S.