- 10 -
All of the coils on the top half of the switching array are series connected. A relay shorts the signal
to the metal structure, bypassing all of the coils above a given band (the bottom half of the
switching array is effectively a mirror image of the top half). The tuning for each band depends on
the tuning for the previous band. Therefore, tuning must start at the 10 m coil pair and progress in
order up to the 20 m band.
The tuning process requires Voltage Standing Wave Ratio (VSWR) measurement. These
measurements can be accomplished using most any antenna analyzer. However, these devices
typically generate a very small signal (less than 0.2 W), and may show higher than expected VSWR
readings. A reading of 1.3:1 at the tuned frequency is typical at this low power. The VSWR
readings should decrease once the antenna is used with 5 W of power or more. The VSWR reading
on your transceiver will likely show a lower VSWR than a low-power antenna analyzer.
Make sure that the coax used for the tuning process is at least 65 feet long, and that both the coax
and control cable are installed at a 45 degree angle as described earlier in this manual.
To tune each band, each of two coils in the coil pair for that band must be
spread or compressed (see photographs below). By spreading each coil in the
coil pair, the tuned frequency for that band will increase. Likewise,
compressing the coils in a coil pair will decrease the band’s tuned frequency.
You should try to spread or compress each of the two coils in a coil pair by
the same amount. Warning:
1) Preparation.
(
Photos shown show the interior of the
DXE-TW2010
)
To
begin the tuning process, remove the center section switching array cover,
and connect the control and coax cables to the switching array box, as
described earlier in this manual. The coax you use for the tuning process
should ideally be the coax you plan to use for the antenna during normal use.
Connect the coax cable to the device you wish to use to measure VSWR, and
connect the control cable to your controller.
2) Start with 10 meters.
Switch your controller to the 10 m band and
determine to
what frequency
the antenna is
best tuned. If
you wish to
increase the
tuned frequency,
spread open each
of the two coils
labeled “10 m” on the switching array
circuit board, as shown in the photos.
3) Tune next band.
Once the 10 m
band is tuned, switch your controller to
the 12m band and tune the 12m band in a similar fashion as you tuned the 10 m band in step 2.
