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RF Systems "MLB" {Magnetic Longwire Balun} - What Is It ?
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December 24th 06, 03:52 PM posted to rec.radio.shortwave
John Smith
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First recorded activity by RadioBanter: Nov 2006
Posts: 2,915
RF Systems "MLB" {Magnetic Longwire Balun} - What Is It ?
wrote:
John Smith wrote:
wrote:
...
Get a Wellbrook.
http://www.wellbrook.uk.com/longwire.html
Interesting instructions. Looks like the "correct way" utilizes a 9:1
voltage balun between feed and antenna and a 1:1 current balun (called
isolator "AFI 5030" in the diagram) between other end of feed and the rig.
Regards,
JS
If the feeder is buried, (coax), then is the isolator required?
Brian
No. The capacitive coupling to ground should be more that sufficient to
offer a low ohmic resistance to ground.
If it was me, I'd still wrap a few turns around an old ferrite core
taken from a discarded am radio and construct a 1:1 current balun
against common mode. However, I'd also run my coax through pvc pipe
when going underground. In fact, I have a long run of coax from the
shack to the antenna farm done exactly that way.
JS
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