Cecil Moore wrote:

The following results are approximate but show the resonance trend on
80m Vs dipole length. Take a certain length dipole and adjust the length
of the 450 ohm ladder-line for resonance on 7.15 MHz. i.e. NOTE: All of
the following antenna systems are resonant on 7.15 MHz. and cover the
entire 40m band with an SWR of 3.5:1 or less (good for built-in
autotuners). Here are the approximate results:

dipole length : feedline length : resonance on 80m

170' : ~85' : 3.62 MHz (3.52-3.72)

160' : ~87' : 3.7 MHz (3.6-3.8)

150' : ~89' : 3.8 MHz (3.7-3.9)

140' : ~91' : 3.92 MHz (3.82-4)

130' : ~92.8' : 4.06 MHz (resonant out of band)

120' : ~94.7' : 4.23 MHz (resonant out of band)

Yesterday I had a 130' dipole that exhibited the above characteristics.
I have changed it to a 144' dipole and now, with one length of
ladder-line, the antenna covers all of 40m and 200 kHz of 80m using the
limited range autotuner built into my IC-756PRO. A bonus is that the
autotuner also tunes this fixed antenna system on 30m and 17m.

Happy New Year, Cecil. Really neat design. Can you describe the
balun you used?

Thanks,

Jim, AC6XG