On 9/12/2020 5:26 AM, Mikek wrote:
My Technical knowledge is limited but, I have built directional AMBCB
antennas. Feed line isolation is critical to make a directional antenna,
directional! I have been criticized and been told, coax cable does not
pick up signal. Must be I don't use the right coax.
This from a previous post I made after I ran out and tested a 230ft Coax
and a 230ft 18ga twisted speaker wire, to see what BCB stations they
received.
You didn't mention what kind of coax you used, but unless you
proactively seeked out double shielded, it WILL leak. I used
to work for Hewlett-Packard/Agilent/Keysight. At one time, HP
has it's own captive wire manufacturing factory. One item of
interest for this discussion is that they made their own
TRIPLE shielded miniature coax to be used in instruments.
They had some connector vendor make special connectors to fit
this HP only coax. In the old HP measurement accessories
catalog, there were "RG-58" class test cables with BNC connectors
colored in HP "mint gray". These were not ordinary RG-58, but
were double shielded. Compared to the black Pomona test cables you
can buy from distributors, the leakage was drastically less.
It is also not surprising that CAT-5 cable has less leakage.
I have used it myself as feedline.
At BCB frequencies, you also have to contend with the skin depth
problem.
Rick N6RK
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