In a message dated 6/2/03 8:59:01 AM Pacific Daylight Time, jim.wil@cox.net
writes:
> What am I missing here--I don't understand the difference between a "balun"
> (at least a 1:1 balun) and a "choke." Possibly K9MI is referring to a 4:1
> (or something else other than 1:1) balun?
>
> Aren't they in fact the very same thing? If they each were in a "black
> box," would they not both appear the same?
A balun is a balanced (antenna) -to- unbalanced (coax) transformer
typically wound on some sort of ferrite core. The newer versions are the
"current
type". There are a couple of good books on the subject.
An RF choke is a air wound coil at the antenna end of a coax run. It
'chokes' RF from going down the coax shield but does nothing for the
balanced-to-unbalanced feedline/antenna situation.
An important purpose of these devices is to keep the outside of the coax
shield from radiating - an important consideration for RFI problems.
Cheers,
Steve K7LXC
TOWER TECH
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