Specifications

17FT-857D Operating Manual
The “TX GND” T/R control line is a transistor “open collector” circuit, capable of handling
positive amplifier relay coil voltages of up to +50V DC and current of up to 400 mA. If you
plan on using multiple linear amplifiers for different bands, you must provide external
band-switching of the “TX GND” relay control line from the CAT/LINEAR jack.
Important Note!
Do not exceed the maximum voltage or current ratings for the “TX GND” line at the
CAT/LINEAR jack. This line is not compatible with negative DC voltages, nor AC
voltages of any magnitude.
Most amplifier control relay systems require only low DC voltage/current switching
capability (typically, +12V DC at 25 ~ 75 mA), and the switching transistor in the
FT-857D will easily accommodate such amplifiers.
CW KEY/KEYER CONNECTIONS
All commonly-available keyer paddles should work perfectly with the built-in Electronic
Keyer. The wiring configuration for the paddle is shown below.
INSTALLATION
LINEAR AMPLIFIER INTERFACING
For straight-key operation, only the tip and shaft connections are used.
Note: Even when using a straight key, you must use a three-conductor (“stereo”) plug. If a
two-conductor plug is used, the key line will be constantly shorted to ground.
When using an external electronic keyer, be absolutely certain that it is configured for
“positive” keying, not “negative” or “grid block” keying. The “key-up” voltage of the FT-
857D is +5V, and the “key-down” current is only about 1 mA.
For CW automated keying using a personal computer, with an external memory keyer pro-
viding for manual sending, it usually is possible to connect the keyed lines together via a
“Y” connector. Check with the documentation accompanying your keyer and your contest/
DX software for any cautions which need to be observed.
COMMON
COMMON
DOT
DOT
DASH
DASH
KEY
GND
GNDKEY