Hardrock-50
Amplifiers with Rev. G and earlier Rear Panels have a Solder Jumper,
SJ305 which connects HR50 5V to DB9 pin 1. On these rear panels, SJ305
must be jumped. On Rev. I Rear Panels, there is a Polyfuse, F301 which
connects HR50 to DB9 pin 1. On this rear panel, nothing needs to be
done.
In all cases, please check HR-50 DB9 pin 1 for the
presence of 5V before attempting to control the amp with your HL2+.
Please note that the HR-50 Rear Panel revision is not the same as what
comes up on the HR-50 display when the HR-50 is powered up.
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Hardrock-50 Menu Settings for use with the HL2+:
2. KX3 Serial: No (Yes inverts the data coming from the HL2 Plus)
3. FT-817 Mode: No
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The correct DB9 cable to use between your HL2+ and the Hardrock-50 is a straight through “regular” M-F serial cable.