CHA 40/20 FD
Page 10
In this example, the antenna is resonant between 7,000 and 7,150 KHz, so the antenna is slightly long if you
want the antenna to resonate at 7,150 KHz. The spread between 7,000 and 7,150 KHz is 150 KHz and, using
our rule-of-thumb from above, that is three half turns on the Line Winders
–
leaving us with the choice to
add one or two half turns on the Line Winders. Since the SWR on 7,150 KHz is lower than on 7,000 KHz, we
should add just one half turn on the Line Winders to increase the resonant frequency of the dipole to around
7,150 KHz. Some trial-and-error may be necessary, but remember as long as the SWR is 2.0 or less across
the intended band, it is good enough.
Figure 5. 3
rd
Case - Antenna is Resonant in Frequency Band.
2.
Be sure the Line Winder is at the end of the Antenna Wire.
3.
Take or make the necessary half turns on the Line Winder. Plate (5) show how to measure and roll up
each half turn of wire.
4.
Secure the wire turns with a Bongo Tie (n) as show in plate (5).
5.
Restart the tuning procedure from step (1).
Plate 5. 1/2 Tuning Wrap.
