Elecraft KPA100 Manual - Manual (Page 50)

50
Turn the high-current supply back on.
Turn off and disconnect the low-current power supply. It should
not be used during the remaining tests.
Fan Test
Set the POWER control for 11 watts or higher.
Edit the PA menu parameter. Tap
D I S P L AY
until you see FAN
n o r (normal). The fan should not be running.
Tap
D I S P L AY
again to set the fan mode to FAN LoHi. The fan
should switch to low speed, which should be barely audible.
Tap
D I S P L AY
to select FAN Hi. The fan should switch to high
speed. Tap
D I S P L AY
to return to FAN nor. Exit the menu.
External Amplifier Keying Test (PA KEY)
Use the MODE switch to select CW mode (mode letter changes to
C). Enter CW TEST mode by holding
V O X
. The letter C should now be
flashing. In this mode, the K2 will not put out any power when you key
the rig either with a key or with the TUNE switch.
Set your DMM to its lowest resistance scale. Connect the (-) probe
to ground, and touch the (+) probe to the tab of Q9 on the KPA100 board
(or to the center conductor of the PA KEY output jack, J7).
The DMM should be indicating a high resistance (typically indicated
by a flashing display). Hold
T U N E
on the K2 to key the transmitter. The
resistance reading should drop to less than 3 ohms.
Tap any switch to exit TUNE mode. Exit CW test mode by holding
V O X
. The mode letter will stop flashing.
Bias Current Adjustment
i
This is the most important KPA100 alignment step. If your
20-amp power supply does not have accurate current measurement
capability in the 0-1 amp range, you'll need a DC milliammeter to set
the bias current. Most DMMs have a suitable high-current range. A
full-scale range of about 1 amp (1000 mA) or higher is required, with
resolution of 0.02 amps (20 mA) or better.
Turn the K2 off.
Turn the high-current power supply off.
As a precaution, connect a dummy load (any power rating) to the
KPA100's antenna jack (J2). This will protect the transmitter in the event
that bias is set too high or the transmitter is keyed.
Rotate R6 on the KPA100 (Bias Set) fully counter-clockwise.
If you're using a DMM to make the current measurements, set it to a
1 amp or higher range. Your DMM may have a separate high-current
tip jack. Consult the DMM's manual before using it.
The DMM must be inserted in series with the positive lead of the
DC power cable. Connect the (+) lead of the DMM to the power supply
side of the circuit, and the (-) lead to the KPA100 side.
Turn on the high-current power supply, then turn on the K2. Using
the menu (secondary), make sure that the PA menu entry is set to ON.
Exit the menu.
Use the MODE switch to select CW mode (mode letter changes to
C ). Enter CW TEST mode using
V O X
(the letter C should flash).
Rotate the POWER control on the K2 through its full range (0.1-110
watts), then set it to 0.1 watts (fully counter-clockwise). The DMM (or
other current meter) should show about 200-400 mA, depending on how
you have the K2 configured.