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K0CQ > TECH 16.09.04 20:16l 20 Lines 785 Bytes #999 (0) @ WW
BID : 21696_W0AK
Read: GUEST OE7FMI
Subj: Re: Pawsey Stub Coax Baluns.
Path: DB0FHN<DB0RGB<DB0SL<DB0FSG<DB0ZKA<DB0KFB<DB0CZ<HB9EAS<HB9AK<K1UOL<
WB3DTG<N0RVX<W0AK
Sent: 040916/0131Z @:W0AK.#CIA.IA.USA.NOAM #:21696 [Des Moines] $:21696_W0AK
From: K0CQ@W0AK.#CIA.IA.USA.NOAM
To : TECH@WW
The so called "current balun" with a gang of toroids around the outside of the
coax does add impedance in series with the outside of the shield and so works
towards balancing the impedance to ground from the shield terminal and the
center conductor of the coax.
Other baluns, like the Pawsey stub do the same thing over a narrower band
where the stub is a quarter wave long.
Still other baluns like the ferrite cored baluns FORCE a voltage balance,
which may not match an imperfectly balanced antenna.
The decoupling stub and current baluns allow the antenna balance to set the
balance and don't force a balance. Often that results in better antenna
performance.
73, Jerry, K0CQ @ W0AK.#CIA.IA.USA
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