Many thanks to all who replied to my query about 1:16 baluns for use with
the Pennant, Flag and Diamond receiving antennas. Many different
configurations for the transformer were suggested.
>From comments by W8JI, real-world testing by W7IUV, and modeling by
EA3VY, it has become obvious to me that F/B ratio is severely degraded
by:
1) Direct feed with coax
2) Other non-isolation of the feedline from the antenna (i.e.,
"autoformers", etc.)
I also suspect that an "unun" might also not be the best answer.
On-the-air tests between K6NDV and myself (both of us have Pennants fed
directly with coax) have shown the F/B to be no better than 10 dB.
Modeling by EA3VY shows the F/B is degraded to about 8 dB when direct-fed
with coax.
Therefore, it appears to be essential that a proper transformer be used
at the feedpoint to isolate the feddline from the antenna. I haven't yet
decided which configuration to use here, but W7IUV's results with his
design and the design suggested by W8JI are on the top of my list.
Tom's (W8JI) design uses a 73 material "binocular" core, with a 2-turn
primary (#29 AWG) and an 8-turn secondary (#26 AWG) wound on top of the
primary. Tom said, "The core is about 1" long and 1/2" thick, and is
commonly stocked". (By whom?)
Larry's (W7IUV) design is a FT50-43 core with 7 turns of #29 AWG for the
primary, and 28 turns of #29 AWG for the secondary, with the primary and
secondary windings separated as much as possible on the core.
73, de Earl, K6SE
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