I recently built a 250 pF transmitting mica
cap into a weatherproof box with a relay
that shorts it out when energized. This cap
is on the antenna side of the balun on my
80 meter inverted vee. The antenna is cut for
CW and operates normally for CW when the relay
is energized. For phone, the relay is not
energized and the cap tunes the antenna to
the phone band. The relay coil is powered by
DC through the coax via an RF choke. Works
perfectly, even at 1500W.
Although this is not elegant, it sure seems a
lot easier and more foolproof than fancy broadbanding
schemes. After all, we don't need wide instantaneous
bandwidth.
Rick N6RK
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