I have constructed a simple telescopic dipole for 2M to 6M to use with my
FT-817ND. This works fairly well but it is prone to RF on the feeder and
some noise pickup. This is almost certainly the result of feeding a
balanced antenna with unbalanced coax. As I need a wideband balun I can't
use traditional VHF tuned baluns. Question is which type of balun can I
scale up (down?) to VHF from HF and maintain efficiency? Toroidal balun?
Ferrite choke? Coiled coax? If ferrites or iron dust cores are involved
then what mix?
Any ideas?
Dick G4BBH

I've used about 8 - 9 inches of #43 beads on RG303 coax for a choke
balun on VHF/UHF with success.
RUK


On Wed, 25 Feb 2009 10:21:45 -0000, "Richard Ferryman"
wrote:

I have constructed a simple telescopic dipole for 2M to 6M to use with my
FT-817ND. This works fairly well but it is prone to RF on the feeder and
some noise pickup. This is almost certainly the result of feeding a
balanced antenna with unbalanced coax. As I need a wideband balun I can't
use traditional VHF tuned baluns. Question is which type of balun can I
scale up (down?) to VHF from HF and maintain efficiency? Toroidal balun?
Ferrite choke? Coiled coax? If ferrites or iron dust cores are involved
then what mix?
Any ideas?
Dick G4BBH

On Wed, 25 Feb 2009 10:21:45 -0000, "Richard Ferryman"
wrote:

I have constructed a simple telescopic dipole for 2M to 6M to use with my
FT-817ND. This works fairly well but it is prone to RF on the feeder and
some noise pickup. This is almost certainly the result of feeding a
balanced antenna with unbalanced coax. As I need a wideband balun I can't
use traditional VHF tuned baluns. Question is which type of balun can I
scale up (down?) to VHF from HF and maintain efficiency? Toroidal balun?
Ferrite choke? Coiled coax? If ferrites or iron dust cores are involved
then what mix?
Any ideas?
Dick G4BBH


I have a 6-meter wire dipole fed with RG8X that was getting about 79
watts forward, 20 watts reverse. A coil of coax, four turns about 5
inches across just below the feedpoint, gave me 100 watts forward. How
this would work on 2 meters, I don't know, but it would be easy to
try.

bob
k5qwg

"Richard Ferryman" wrote in
news
I have constructed a simple telescopic dipole for 2M to 6M to use with
my FT-817ND. This works fairly well but it is prone to RF on the
feeder and some noise pickup. This is almost certainly the result of
feeding a balanced antenna with unbalanced coax. As I need a wideband
balun I can't use traditional VHF tuned baluns. Question is which
type of balun can I scale up (down?) to VHF from HF and maintain
efficiency? Toroidal balun? Ferrite choke? Coiled coax? If ferrites
or iron dust cores are involved then what mix?

Here is a design: http://www.vk1od.net/balun/G1-1-FT140-61/index.htm .

There are many alternatives.

Owen

Any ideas?
Dick G4BBH