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G8MNY > TECH 12.05.18 10:03l 48 Lines 1550 Bytes #-2492 (0) @ WW
BID : 19347_GB7CIP
Read: DK3UZ GUEST OE7FMI
Subj: Coax Sleeve Balun
Path: DB0FHN<DB0PM<OE2XZR<OE5XBR<OE1XAB<HG8LXL<N0KFQ<NS2B<N9PMO<I0OJJ<
GB7CIP
Sent: 180512/0838Z @:GB7CIP.#32.GBR.EURO #:19347 [Caterham Surrey GBR]
>From g8mny%gb7cip.#32.gbr.euro@i0ojj.ampr.org Sat May 12 10:41:27 2018
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From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (Updated Dec 04)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
This type of balun is to be found in most textbooks & many aerial designs. It
is a 1:1 balun & does not alter the impedance.
Balun is made from ¬ wave lengths of scrap coax (longer needed to cover the
fatter outer) braid or pipe over the top of the feeder. It is electrically
connected to the coax braid 1/4 wave from the balanced feeder connections.
ÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
BALANCED ÚÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
BÄÄÄ) UNBALANCED FEEDER
BÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
ÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
This works by hiding the unbalanced outer aerial connections from the outside
world so it can't radiate.
In practice I recommend heatshrink sleeving & heat glue it used to seal the add
outer section.
Common mode Z is only high at the resonant frequency, where it eliminates any
outer feeder current on the unbalanced coax.
Z
Hi ³ .".
³ / \
Low³...-' `-.....
ÀÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄ F
Fo
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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