Therefore, strange though it may sound, the
HW-101's final stage can be used as an
amplifier by feeding an exciter signal into its
receiver input. Testing reveals that this
presents a reasonable load impedance to the
K2, and about 1 watt of drive is required to
bring the HW-101 to full output. The
modification consists of wiring one of the rear-
panel jacks as an exciter input, and
(optionally) wiring another as a receive
antenna output.
ai.1. The Basic Mod
Remove the bottom cover. Run a short length
of miniature coax from the "Spare" rear-apron
phono jack to pin 4 of relay RL1. (This is the
relay near the antenna connector). This is the
same pin to which L905, the 8.5 MHz trap, is
connected.
Re-label the Spare jack "Exciter In".
Build the K2 Amplifier Keying Circuit, which will drive the HW-101's T-R relay from the
8R output of the K2. I elected to build this in an external enclosure and connect it
through the Aux I/O connector, but it can also be installed inside the K2. (Be sure to
enable the 8R Hold feature of the newer firmware release.) Connect the output of this
circuit to the PTT and ground lines of the HW-101's microphone connector. You can
either use a substitute microphone plug, or wire the HW-101's PTT line to a rear-panel
phono jack.
Verify that the PTT circuit is working correctly, then connect the antenna output of the
K2 to the new Exciter In jack, and the antenna to the HW-101's antenna jack. Verify that
the K2's receiver is working normally through the new antenna connection.
I have the KAT2, and I found it useful to connect the K2's Ant2 output to the HW-101,
and Ant1 to an antenna switch which switches the antenna between the K2 and the
HW-101. This makes it easy to switch between "barefoot" and the amplifier.
Be sure to disconnect the K2 completely when using the HW-101 as a transceiver.
Hot Water for the K2 Page 184
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