NOTE: The TX GND OUT pin (pin 2) of the       LINEAR jack is a transistor "open       collector" circuit. It is capable of handling       positive relay coil voltages up to +60V DC       at 200 mA or +30V DC at 1A. If you plan       to use multiple linear amplifiers for different       bands, you must provide external band       switching of the "Linear Tx" relay control       line from the "TX GND OUT" line at the       LINEAR jack. The specified range for ALC voltage to be       used with the FTDX 1200 is 0 to -4 Volts       DC. Amplifier systems utilizing different ALC       voltages will not work correctily with the       FTDX 1200, and their ALC lines must       not be connected if this is the case.

IMPORTANT NOTE! Do not exceed the maximun voltage or       current ratings for the TX GND OUT pin       (pin 2) of the LINEAR jack. This line is not       compatible with negative DC voltages, or       AC voltages of any magnitude. Most amplifier relay control systems require       only low DC voltage/current switching       capability (typically, +12V DC at 25~75       mA), and the switching transistor in the       FTDX1200 will easily accomodate such       amplifiers.

NOTE When the FC-40 is connected to the FTDX 1200, TX GND (pin 2) of the TUNER jack and the :LINEAR jack (pin 2) are common circuits. Therefore the maximun voltage at TX GND (pin 2) of the LINEAR jack must not exceed +5V. End of "Interfacing to Other Linear Amplifiers"