Hi Andy,
I am using a 204BA (4 el on a 26 ft boom). The directors and reflectors are
grounded to the boom. So, the total 30 M dipole includes the boom length and
the effect of the reflector and outer director. My Gamma match is a piece of #
14 wire that runs from the end of the boom to the mast on the side opposite
the 20 M driven el.
There is an insulator in the wire at the mast. The wire slopes from about 16
inches up the mast down to the outer end of the boom. I was able to tune this
configuration to either 40 M or 30 M using a variable capacitor in series with
the feedline at the insulator. The series capacitor is adjusted to about 100
pf on 30 M. Note you may want to move the tie point to the mast up or down a
bit to optimize the match. I was able to tune it down to about 1.1:1 at the
band center.
I have the 204BA at 74 ft and I think the matched boom works out GREAT on 30
or 40 M. I have used it on both bands.
Good luck,
Bruce AA4Z
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