On 8/7/01 4:12 PM, Tom Rauch at w8ji@akorn.net wrote:
>There must be some misunderstanding Bill. Current baluns are the
>less core-critical type of balun.
That's good to know.
>By far the most core, power, and impedance critical balun is the
>voltage type balun. It is also the balun that virtually always offers
>the poorest antenna balance.
Also good to know. Exactly the type of information I need.
>One problem with bead baluns is they offer a very low impedance
>per bead, and most of that impedance is resistive. So the stack
>tends to get hot in situations where common-mode voltage from the
>feedpoint to the coax (across the balun core stack) is high.
Is this typical of a tribander whose feedpoint impedance is empiracally
designed to be about 50 ohms?
>You are better off winding an air core choke out of coax unless you
>have a space limitation, because impedance actually goes up by
>somewhere around the square of the turns compared to a one-for-
>one impedance vs size and cost increase in a stack of beads.
Why not just wind a current-type balun using a big core and some very
small-diameter teflon coax? You get the turns advantage of a coil,
without the size, weight and bulk problems of a coiled coax balun?
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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