Elecraft PX3 Owner's Manual - Manual (Page 24)

24
Opposite Sideband Nulling
Complete nulling of the opposite (unwanted) sidebands depends upon accurate setting of the phase and
amplitude of the I/Q outputs from the KX3. Although the PX3 comes with settings that should provide good
suppression of the unwanted sideband, it may be possible to improve them if you wish.
Getting Ready
A signal source with a variable level of about -40 dBm on each of the bands listed in Table 1 is required. The
PX3 contains a built-in signal generator that is suitable or you can use an external signal generator such as the
Elecraft XG3. If you use the built in signal generator in the PX3, set up the equipment with a coupling wire to
introduce signal into the KX3 antenna as shown on page 27.
 Remove your microphone, keys, etc., that might be accidentally bumped to avoid transmitting into your
signal source.
 You can save a lot of button-pushing by assigning the
OSB Ampl (Opposite Side Band Amplitude) and
OSB Phaz (Opposite Side Band Phase) menu functions to the function keys. For example, to use FN1
for OSB Ampl and FN2 for OSB Phaz as follows:
o Hold L AB E L S to display the labels assigned to the FN keys.
o Tap M E N U and turn the SELECT knob to OSB Ampl, then tap F N 1 and note that the
label for FN1 changes to OSB Ampl .
o Turn the SELECT knob to OSB Phaz , then tap FN2 and note that the label for FN2
changes to OSB Phaz .
 Tap Menu (if you aren’t still in the menu) turn the
SELECT knob to Lvl Mode and tap the knob
again to display dBm. Exit the menu.
 On the PX3 front panel, set the display parameters as follows:
o S P A N : 50 (kHz).
o R E F : 130 (dBm)
o S C AL E :
80.0 (dB)
o D I S P : Tap to turn off the waterfall display.
 Before changing any settings, record the current amplitude and phase values in the initial settings
columns for each band on Table 1 on page 24. This is important in case you want to return to the factory
defaults. Tap the
B A N D + and B A N D - switches on the KX3 to select each band and tap the F N 1 and
F N 2 switches on the PX3 to display the OSB Ampl and OSB Phase values shown.
 If you have transverters installed, the settings obtained on the HF band the transverter uses for an I.F.
may not be optimum because the tuning range the transverter requires may fall outside of the normal
Ham band. If you have a suitable signal generator, you can adjust the amplitude and phase for each
transverter band. Those settings will not change the adjustments for normal H.F. operation on the band
used as the I.F. You will need a signal generator capable of covering the input frequency for each
transverter. Table 2 provides you a place to note and record the settings.