RF choke/balun question
 

What size loop and how many turns should I use to create a RF choke with my
coax, right before the antenna?

Vinnie S.

Vinnie S. wrote:
What size loop and how many turns should I use to create a RF choke with my
coax, right before the antenna?

Vinnie S.

8 to 10 turns on an 8 inch form, remove the form, with RG-8X or similar
"mini" coax. 6-8 turns with RG-8 or 213.

HTH

-SSB

On Wed, 26 Jan 2005 21:25:07 GMT, SideBand wrote:

Vinnie S. wrote:
What size loop and how many turns should I use to create a RF choke with my
coax, right before the antenna?

Vinnie S.

8 to 10 turns on an 8 inch form, remove the form, with RG-8X or similar
"mini" coax. 6-8 turns with RG-8 or 213.

HTH

-SSB


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

Vinnie S.

Vinnie S. wrote:
On Wed, 26 Jan 2005 21:25:07 GMT, SideBand wrote:


Vinnie S. wrote:

What size loop and how many turns should I use to create a RF choke with my
coax, right before the antenna?

Vinnie S.

8 to 10 turns on an 8 inch form, remove the form, with RG-8X or similar
"mini" coax. 6-8 turns with RG-8 or 213.

HTH

-SSB



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?

-SSB

On Wed, 26 Jan 2005 22:03:22 GMT, SideBand wrote:

Vinnie S. wrote:
On Wed, 26 Jan 2005 21:25:07 GMT, SideBand wrote:


Vinnie S. wrote:

What size loop and how many turns should I use to create a RF choke with my
coax, right before the antenna?

Vinnie S.

8 to 10 turns on an 8 inch form, remove the form, with RG-8X or similar
"mini" coax. 6-8 turns with RG-8 or 213.

HTH

-SSB



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.

Vinnie S. wrote:
On Wed, 26 Jan 2005 22:03:22 GMT, SideBand wrote:


Vinnie S. wrote:

On Wed, 26 Jan 2005 21:25:07 GMT, SideBand wrote:



Vinnie S. wrote:


What size loop and how many turns should I use to create a RF choke with my
coax, right before the antenna?

Vinnie S.

8 to 10 turns on an 8 inch form, remove the form, with RG-8X or similar
"mini" coax. 6-8 turns with RG-8 or 213.

HTH

-SSB



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

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