Elecraft KXPA100 Manual - Manual (Page 47)

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Set your transceiver on any frequency in the 20 meter (14 MHz) band and prepare to transmit in a full-
carrier mode such as CW or Tune.
Confirm that the KXPA100 is working: set the transceiver for about 2.5 watts output and make a short
transmission to confirm that the amplifier is producing substantially more than 2.5 watts into the dummy load.
Turn the ALC potentiometer counter-clockwise 10 turns. That ensures it is at its minimum setting.
Set your transceiver for the normal drive level you plan to use with the KXPA100. In any case, the output
must be less than 8 watts. With a Yaesu FT-817 set the output for 5 watts.
CAUTION
In the following steps, transmit no longer than 10 seconds at a time if you have the
bottom cover removed and the KXPA100 sitting on its heat sink, due to the limited
airflow around the fins in that position. After a 10-second transmission, allow 20
seconds for the amplifier to cool before transmitting again.
Transmit in CW or tune mode to provide a steady carrier and adjust the ALC potentiometer to
indicate 100 watts on the KXPA POWER OUT LEDs. Optionally you can connect an external wattmeter
to the KXPA100 but remember that even good wattmeter readings will vary. Use the KXPA100 LED to
determine 100 watts output.
If you removed the bottom cover, you also removed the front panel. With the amplifier
inverted on your table, the 100 watt LED is the on the bottom row (nearest the heat sink)
and the seventh LED from the end closest to you as you access the ALC potentiometer.
That completes the ALC adjustment.
Removing and Replacing the KXPA100 Bottom Cover
The KXPA100 enclosure has three parts in addition to the finned heat sink on the top: the bottom cover (called
the U-Cover because of its shape) and the front and rear panels.
Normally you would never need to remove the covers except perhaps to adjust the ALC for proper operation
with certain transceivers.
You will need:
1. #1 size Phillips screwdriver. Some makes of size #0 screwdriver may fit better. Always use the
screwdriver that best fits the screw in each step. To avoid damaging screws and nuts, a power
screwdriver is not recommended.
2. Needle-nose pliers, 4” to 6” may be helpful.
3. Soft cloth or clean, soft static dissipating pad to lay cabinet panels on to avoid scratching.
CAUTION
Use Electro-Static Discharge (ESD) protection if you touch any components inside the
KXPA100 other than the adjustment screw on the ALC potentiometer. Failure to take
ESD precautions may result in damage to your amplifier.