What Rick reported is perfectly sound!
If the currents in each of the bifilar pair are balanced - that is they
are equal magnitude and opposite phase - there will be no net flux in
the core. If they are *not* balanced, there *is* then a CM component
that will tend to drive flux in the core, and be opposed by that flux.
In other words, that arrangement tends to drive current balance in the
two legs of the ladderline.
It's exactly the system I use to transition from ladderline on my
multiband doublet to my unbalanced 238 tuner.
73,
Steve G3TXQ
On 22/04/2013 15:16, Walt K8CV wrote:
Sorry, I find this a wee bit hard to swallow. I picture a big lump of
large toroids, with two plastic pieces of coax jacket going through
them, with one wire in each that connect to the open wire. This
conglomeration is serving some useful purpose? The little RF electrons
going NORTH to the antenna are passed by the gate keeper in the
conglomeration? WOW, that's interesting, as to the little electrons
reflected from the antenna he says " no, you can't pass "! Is there
some magic DSP going on here? How does this toroid know all this? Have
toroids become sentient and aware over night? I can see the scenario
when the ( sic ) good RF is on the inside of a coaxial cable and
protected from the toroid by the cable shield, getting to the antenna
and the ( sic ) bad RF, ON THE OUTSIDE OF THE COAX SHIELD, getting
stopped when they are reflected, but the open wire setup looks a
little DODGY to ME! This is the month of APRIL, but not APRIL 1 :-)
right ??
FLAME SUIT ON !!
Walt K8CV
----- Original Message ----- From: "Rick - DJ0IP / NJ0IP" <Rick@DJ0IP.de>
To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Sent: Monday, April 22, 2013 8:53 AM
Subject: Re: [TenTec] Built in SWR meter bannans
Dave,
Sorry, my memory failed me there.
It was long ago that I did this.
I had to search for my notes and drawings (file). Found them.
Actually I removed the center cable from coax, and discarded the
shield and insulation. Then I put two pieces in parallel and ran them
through the same beads; lots of beads.
Then I covered it with heat-shrink tubing and fed the open wire into
one end, and connected the other end through a short coax stub to my
antenna tuner.
So yes, I did use only the center of two pieces of coax, but they ran
through the same string of beads, not separate beads.
73
Rick
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