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The signal from the KPA100's 4-MHz crystal oscillator (X2) may be
audible at the high end of the 80-meter band. If this is the case, you can
move it to a point just above 4 MHz using trimmer C27. The signal from
the 4-MHz oscillator on the K2 Control board may be much stronger.
Rotate C27 slightly to identify the KPA100 signal.
SWR Bridge Null Adjustment (C1)
Connect a 50-ohm dummy load rated at 5 watts or higher to the
KPA100's SO239 antenna jack (J2).
Select the 40 meter band (7000-7300 kHz). Set the K2's POWER
control for about 5 watts.
Temporarily remove power from your K2/100 and set the FWD and
REFL potentiometers on the KPA100 (R26 and R27) for about 43K ohms
resistance measured between the center arm and ground.
Set the SWR null trimmer (KPA100-C1, near the antenna jack) so
that its adjustment slot is
perpendicular
to the KPA100 rear panel.
Note:
With the KPA100 installed, the TUNE mode display includes both
forward power and SWR. For example,
5.0 1.0 -1
means
5.0 watts, output, and an SWR of 1.0:1.
Locate a small insulated-handle screwdriver or tuning tool, and
prepare to adjust C1 on the KPA100. Enter TUNE mode by holding
T U N E
. Adjust C1 for an SWR indication of
1.0-1
on the K2 LCD.
Cancel TUNE mode by tapping or holding
T U N E
again.
Note:
You'll see an indication of
1.0-1
over a small range of C1's
rotation. Position C1 at approximately the middle of this range, repeating
the TUNE adjustment several times if necessary.
Optional SWR fine adjustment
You may be able to adjust C1 more accurately by measuring the reflected
voltage directly using a DMM or an analog voltmeter. Connect the (-)
lead to the ground jumper on the KPA100 board (near U1). Touch the (+)
lead to TP4 near pin 1 of KPA100-U5 (LM358). Repeat the TUNE
procedure from above, adjusting C1 for a reading as close as possible to
zero volts on the voltmeter.
8R Menu Setting
The
t-r
control must be set to
8r hold
when the KPA100 is installed. To
check the setting, tap
M E N U
and locate
t - r
by turning the VFO knob or
pressing the
B AN D +
or
B AN D -
buttons. Hold
E D I T
to enable the
t - r
function, then tap
D I S P L AY
to toggle between
8 r n o r
and
8 r h o l d
. Be
sure
8 r h o l d
is selected, then tap
M E N U
twice to exit the menu
function.
Power Calibration (R26 and R27)
Connect an external wattmeter between the KPA100 antenna jack
(J2) and the 50-ohm dummy load.
Select the 40 meter band (7000-7300 kHz). Set the POWER control
for 5.0 watts.
Note:
This calibration step can be done later at a higher power level if
your wattmeter doesn't have an accurate low-power scale.
Locate a small flat-blade screwdriver and prepare to adjust R26 on
the KPA100. Enter TUNE mode on the K2. Adjust R26 for a power
indication on the K2 LCD that matches the reading of the external
wattmeter. Cancel TUNE mode. Repeat as needed until the K2's LCD
shows the same power level as the external wattmeter.
Set R27 to exactly the same position as R26 (visually). This will
provide adequate accuracy for SWR readings.
Check the SWR in TUNE mode on every band. The SWR should be
close to 1.0 to 1 on all bands (
1.0-1
).
Temperature Calibration and K2 Current Limit Set
Turn the KPA100 bias control, R6, fully counter-clockwise.
