Elecraft K3 Assembly Manual - Manual (Page 65)

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Power Amplifier Jumper Block
The Power Amplifier (PA) jumper block is required to operate the K3 without the optional KPA3 100 watt
power amplifier module installed. Your RF board was shipped with the jumper block installed. Even if you are
planning to install the KPA3 at this time, do not remove it until instructed to do so. You will be performing
some essential tests and calibration procedures before the KPA3 module is installed.
If you remove it for any reason before installing the KPA3, replace it as shown in Figure 90. Inspect the
position of the jumper block carefully to endure it is mated with the four pins at the ends of both connectors.
Your K3 may be damaged when power is applied if the jumper block is positioned incorrectly!
Figure 90. Installing the PA Jumper Block.
Finishing the Enclosure
Even though you may be planning to install the KPA3 100 watt amplifier at this time, you must complete the
enclosure to run some essential tests and calibration procedures first. These tests require the enclosure panels be
in place, particularly the bottom cover that acts as a heat sink for the low power amplifier (LPA) transistors.
Fan Opening Cover
A large opening in the rear panel is provided for fans required to cool the KPA3 100-watt amplifier module. If
you did not purchase the KPA3 option with your kit, a blank panel is provided to cover this opening. If you
purchased the KPA3 option with your kit, skip the following two steps and go directly to AUX RF Cable below.
The blank panel has a BNC connector hole marked ANT3. This is for the optional K144XV module. If you
do not have the K144XV, press a BNC Hole Cover into the opening in the panel with the small, smooth end of
the cover on the side of the panel that has the ANT3 label.
Install the panel in the opening on rear panel with a 3/16” (4.8 mm) black pan-head screw (SS) into the
threaded bushing at each corner. Do not use washers under the screws.
AUX RF Cable
If you installed the AUX RF connector for the KRX3 subreceiver, that cable should be lying near the rear
panel. If the KPA3 shield is installed it will be inside the shield. Check the cable carefully to ensure you have
fully insulated the metal conductor at the end. Failure to do so may result is severe damage to your K3 if it
comes in contact with a live circuit. Recommend you tape the cable to the rear panel or, if the KPA3 shield is
installed, tape it to the shield to keep it secure inside the K3.