Elecraft K2ATOBKIT - Manual (Page 14)

14
Receiver Pre-Alignment, 10-30 meters
This step is necessary if you made any changes to the
10-30 m band-pass filters (steps 4, and 6, page 8). If
you didn't make these changes, continue with Fine-
Tuning Filter Settings, page 15.
Switch to 20 meters and set the VFO for about
14100 kHz.
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.
i
Since some inductors are shared between two
bands, you must always align the bands in the order
indicated. Always use this procedure if you re-align the
filters later.
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.)
Note: When switching to each of the remaining bands
to be aligned, you'll need to inject a signal or use an
antenna.
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.
Transmitter Alignment, 10-30 Meters
Set the POWER control for 2.0 watts. Connect a
dummy load at the antenna jack.
Switch to 30 meters. Adjust L8 and L9 for
maximum power output in TUNE mode. Avoiding
using TUNE mode for more than 5 seconds at a time.
Switch to 20 meters (14100 kHz) and adjust C21
and C23 for maximum power output.
Switch to 15 meters (21100 kHz) and adjust L10
and L11 for maximum power output.
Switch to 17 meters (18100 kHz) and adjust C32
and C34 for maximum power output.
Switch to 10 meters (28200 kHz) and adjust L12
and L13 for maximum power output.
Switch to 12 meters (24900 kHz) and adjust C44
and C46 for maximum power output.
AGC Threshold Test
A few K2 builders found that their overall receive gain
was too low because of a less-than-ideal AGC
threshold setting. If you think you might benefit from a
change in this threshold, follow the steps below.
Otherwise, skip to the next page.
Connect an antenna to the K2, and switch to a
quiet band (one with little atmospheric noise). Turn
AGC off by holding the P R E / A T T N and A G C
switches together.
If the level of background noise increases
significantly with AGC off, even on a quiet band, you
may benefit from an adjustment to the AGC threshold.
Remove the Control board and temporarily substitute a
potentiometer for R1, presetting it to R1's fixed value.
Once you find a value of R1 that brings I.F. gain up
slightly while not compromising AGC performance on
large signals, you can install a fixed resistor of that
value.
If you did make a change to R1's value, you'll
need to recalibrate C A L S H I and C A L S L O
(owner's manual, page 84).