Assuming that the feedline is ladder line or open wire for low loss, add
an eighth wavelength of feedline on 20 meters (about 8 feet). That may
or may not help on 10 meters (the problem is thee same, the radiator has
a very high impedance, and the feedline must be used as an impedance
transformer to bring it down. Maybe some work with the ARRL program
TLW is in order.
73,
Don W3FPR
On 12/8/2012 4:14 PM, Vic Rosenthal wrote:
If the feed line happens to be near an even multiple of a half wavelength the
impedance will be very high and there will be a voltage loop (HV point) at the
tuner. As someone else noted, losses would also be very high, so using a 40m
coax fed dipole on 20 is a poor idea.
Vic k2vco
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