On 11/18/2015 6:05 PM, Dan Maguire via TowerTalk wrote:
I was particularly impressed with the "look inside" view of his 4:1
balun along with the VNWA insertion loss and SWR measurement results as
shown on his OCF-8010E-3K page:
http://myantennas.com/wp/product/ocf-8010e-3k-windom/
Dan, AC6LA
I'm not so impressed. The web site says that the
test is done by the "back to back" balun method.
This isn't a very thorough test because one of
the cores in each balun isn't really doing anything.
A pair of back to back un-un's would similarly pass
this test. The test doesn't really establish that
the "balun" is a balun, only that it is an all pass
network when connected to another instance of itself.
A better design is to cascade a 50 ohm common mode choke
with a balanced 50 ohm to balanced 200 ohm transformer.
Rick N6RK
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