Howard Lester wrote:
"dave" wrote

A BalUn would help a lot.

For what? If the antenna system is balanced (as are dipoles, inherently), I
seriously doubt a balun would be good for anything.



Most every practical dipole installation has some imbalance in the
installation (the trees are closer to one side than the other, etc.).. a
choke to prevent RF current from flowing on the outside of the feedline
will at least make the pattern more consistent with expectations.
Might make the tuning less "twitchy" too (because you've decoupled the
effect of things near the feedline).

Certainly, a choke at the entrance to the shack is a great way to keep
RF outside.

Jim Lux wrote:
Howard Lester wrote:
"dave" wrote

A BalUn would help a lot.

For what? If the antenna system is balanced (as are dipoles,
inherently), I seriously doubt a balun would be good for anything.


Most every practical dipole installation has some imbalance in the
installation (the trees are closer to one side than the other, etc.).. a
choke to prevent RF current from flowing on the outside of the feedline
will at least make the pattern more consistent with expectations. Might
make the tuning less "twitchy" too (because you've decoupled the effect
of things near the feedline).

Certainly, a choke at the entrance to the shack is a great way to keep
RF outside.

A choke wastes power.

dave wrote:
A choke wastes power.

I certainly wish that the RF power that left my lip
with an RF burn scar had been wasted by a choke.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

dave wrote:
Jim Lux wrote:

Certainly, a choke at the entrance to the shack is a great way to keep
RF outside.

A choke wastes power.

A properly designed common mode choke does not waste power.

Roy Lewallen, W7EL

dave wrote:
Jim Lux wrote:
Howard Lester wrote:
"dave" wrote

A BalUn would help a lot.

For what? If the antenna system is balanced (as are dipoles,
inherently), I seriously doubt a balun would be good for anything.


Most every practical dipole installation has some imbalance in the
installation (the trees are closer to one side than the other, etc.)..
a choke to prevent RF current from flowing on the outside of the
feedline will at least make the pattern more consistent with
expectations. Might make the tuning less "twitchy" too (because you've
decoupled the effect of things near the feedline).

Certainly, a choke at the entrance to the shack is a great way to keep
RF outside.

A choke wastes power.

How might this happen? The choke's not in the desired RF path (i.e. the
inside of the coax and the antenna itself)

Putting an RF impedance of, say, 5K in series with the current on the
OUTSIDE of the shield should effectively reduce the current to zero, so
there's no power being dissipated in the choke.

Yes, if you use a choke with too low an impedance, it might dissipate power.

Jim Lux wrote:
Howard Lester wrote:
"dave" wrote

A BalUn would help a lot.

For what? If the antenna system is balanced (as are dipoles,
inherently), I seriously doubt a balun would be good for anything.


Most every practical dipole installation has some imbalance in the
installation (the trees are closer to one side than the other, etc.).. a
choke to prevent RF current from flowing on the outside of the feedline
will at least make the pattern more consistent with expectations. Might
make the tuning less "twitchy" too (because you've decoupled the effect
of things near the feedline).

Certainly, a choke at the entrance to the shack is a great way to keep
RF outside.

A choke wastes power.