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[TowerTalk] Voltage or Current Balun?

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Subject: [TowerTalk] Voltage or Current Balun?
From: W8JI@contesting.com (Tom Rauch)
Date: Tue, 7 Aug 2001 16:12:31 -0400
> Power handling capability isn't really an issue here. I know some people
> have had trouble trying to run a full gallon into some current-type
> baluns. I don't own an amplifier. If I ever did, it would probably be in
> the 400-1000 watt range.

There must be some misunderstanding Bill. Current baluns are the 
less core-critical type of balun. 

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.

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.

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.

 

73, Tom W8JI
W8JI@contesting.com 

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