ELECRAFT KX3 Owner's Manual page 27

 After you are comfortable with setting up and
using the spectrum display, you can connect the
USB/serial cable between the PC and the KX3.
 Typically, some spectral noise will appear in
the display in the form of "spikes" or
modulation sidebands. These can arise from
several sources, including nearby power
supplies, ground noise, or the computer and its
peripherals. You can often use isolation
transformers, improve grounding, and use
shielded cables to reduce the amplitude of these
signals.
 The HDSDR program can also display the
actual frequency range in use if it is set up to
communicate with the KX3. To do this, set up
the program to use KX3, K3, or Kenwood
protocol, and connect the KX3's ACC1 jack to
a USB or RS232 port on the computer (see pg.
5). The program should then correctly display
the actual signal frequencies as you tune the
KX3. You may also be able to tune the KX3
from the program, depending on the program's
features.
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