I built a 4:1 balun based on an old QST article.
http://www2.arrl.org/members-only/ti...df/9008028.pdf

I used 10 Fair-Rite 2643540002 beads on each of the 2 pieces of
RG-71B/U 93 ohm coax. These are #43 ferrite .562 OD .250 ID and 1.125
inches long.

Is this enough #43 ferrite to be an effective balun on 80 thru 10
meters?

The balanced side is connected to about 30 ft of 450 Ohm window line
that feeds a 135 ft off center fed dipole at 75 ft from one end. The
unbalanced side is connect to the coax output of an AEA ET-1 manual
tuner through 20 ft of Mini 8 coax.

Will this type balun work with the high swr that it will see on some
bands?

I can get a good match on 80 thru 10 meters except for 12 meters. It
seems to work, but I may be converting more RF to heat than radiating.
The external balun is a matter of convenience as it is a lot easier to
bring the coax into the tuner than it is to bring in the window line.
Would it be better to just use a 1:1 balun between the coax and the
window line?

Mike kc9doa

On Sun, 25 Mar 2007 07:16:52 GMT, Mike M.
wrote:

I can get a good match on 80 thru 10 meters except for 12 meters. It
seems to work, but I may be converting more RF to heat than radiating.

Hi Mike,

Perhaps, but without more data, it could be working just as well as it
appears to be.

Would it be better to just use a 1:1 balun between the coax and the
window line?

That is simple enough to check by simply moving one leg of the dipole
to the choked coax feeding the other side (and abandon the redundant
choked line). This, of course, returns us to my observation above.
Without more data, there is no way to say what would be "better."

73's
Richard Clark, KB7QHC

Mike ,
You might want to try my balun .
http://www.bloomington.in.us/~wh2t/balun.html
You can use light guage wire for lower power applications .
73, Ace - WH2T

Dr.Ace wrote:
You might want to try my balun .

Are you sure 12 turns on a one inch air core
coil form is good enough for 160m? Wouldn't
the reactance need to be in the hundreds
of ohms?
--
73, Cecil, w5dxp.com