Opinions please...

[Julius Fazekas n2wn]

Greetings All,

Ok, I want to build a balun. It should be able to
handle 200 Watts RF (safety factor built into this
number), 80 thru 30 Meters (160M would be nice) and be
efficient. I want to use a Toroid to do this so it
fits inside an enclosure. My question is how small of
a toroid can I use and which variety? I'm thinking
something in the T-100-6 range.

Thanks,
Julius
n2wn
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[Masleid, Michael A.]

Hello Julius

> Ok, I want to build a balun. It should be able to
> handle 200 Watts RF (safety factor built into this
> number), 80 thru 30 Meters (160M would be nice) and be
> efficient.

Well, I'm guessing here, but I think you'll need to
use ferrite to keep the inductance reasonable.  You
also want to keep the B field low so it doesn't get
hot or non linear.  Let's shoot for 200 gauss peak.

If you were running 200 watts into 50 ohms, you'd need
100 volts on the line, but that would be into a matched
load.  Into a doublet lets say we have a 10:1 VSWR, so
we'll see 1000 volts at the balun.

How many turns?  Lets try 10.  Frequency, 1.8 MHz.

Using Fair-Rite's formula, we'll need 6.26 cm squared
core area.  If you use FT-100-43 I think you'd need
to stack them up until you have a 1" diameter by 5"
long tube.

I might be way off though.

73, de Michael, AB9GV
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[Stuart Rohre]

All  the hard work of balun design has been done in the balun kit offered by
The Wireman, Landrum S.C. (on web).  I believe Amidon might also have Balun
kits and both fit the power range you want.

Typically, it is hard to get one balun to work 160m to 10m.  See the Jerry
Sevick books,  (Baluns and Ununs) for worked out examples that never get
hot.
-Stuart
K5KVH


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[Charles Greene]

Julius,

Off hand, without doing the design, I'd say something on the order of one
F-140-43 or two F-114-43.  You can't get there with a T-XX-6; not enough
umph.  Takes F-XX-61 at the least.  Why limit it to 160 to 30 meters? The
BL-1 covers 160 through 6.  See http://www.njqrp.org/balun/index.html

Chas,

W1CG

At 02:25 PM 10/12/2004, J F wrote:

>Greetings All,
>
>Ok, I want to build a balun. It should be able to
>handle 200 Watts RF (safety factor built into this
>number), 80 thru 30 Meters (160M would be nice) and be
>efficient. I want to use a Toroid to do this so it
>fits inside an enclosure. My question is how small of
>a toroid can I use and which variety? I'm thinking
>something in the T-100-6 range.
>
>Thanks,
>Julius
>n2wn

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