ELECRAFT 73
Receiver Pre-Alignment
Since the same filters are used on both receive and transmit, it is
possible to align all the remaining bands on transmit only.
However, you can pre-align the filters on receive by using a signal
or noise generator, separate ham transceiver, or on-air signals and
atmospheric noise. This pre-alignment on receive will make
transmitter alignment easier, since the filter adjustments will
already be at or close to their final values.
Switch to 80 meters and set the VFO for about 3750 kHz
(mid-band). Turn on the RF preamp by tapping
P R E / A T T N until
you see the PRE annunciator turn on.
Use a signal generator or an antenna to inject a signal or noise
at this frequency.
Adjust L3 and L4 for maximum signal strength.
i
Since some inductors are shared between two bands, you
must always align the remaining bands in the order indicated.
Always use this procedure if you re-align the filters later.
Switch to 20 meters (14100 kHz) and turn on the preamp. Set
C21 and C23 to their mid-points. Adjust L8 and L9 for maximum
signal strength. (This step pre-sets C21, C23, L8, and L9 before
final adjustment in the next two steps.)
Switch to 30 meters (10100 kHz) and turn on the preamp.
Adjust L8 and L9 for maximum signal strength.
Switch back to 20 meters (14100 kHz). Adjust C21 and C23
for maximum signal strength.
Switch to 15 meters (21100 kHz) and turn on the preamp.
Adjust L10 and L11 for maximum signal strength.
Switch to 17 meters (18100 kHz) and turn on the preamp.
Adjust C32 and C34 for maximum signal strength.
Switch to 10 meters (28200 kHz) and turn on the preamp.
Adjust L12 and L13 for maximum signal strength.
Switch to 12 meters (24900 kHz) and turn on the preamp.
Adjust C44 and C46 for maximum signal strength.
This completes receiver alignment.
i
During receiver alignment, you may have noticed that
signal strength is somewhat lower in volume when you select the
narrowest filter (100 Hz setting, FL4). This is because the K2's
crystal filter is optimized for wider bandwidths (250-800 Hz).
Despite the slightly greater attenuation, the narrower settings are
very useful in reducing QRM (interference) from strong, nearby
signals. (Any of the filter settings can be changed, and FL2-FL4 can
even be turned OFF. See page 85 for information on customizing
filter settings.)
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