34
Transmitter Operation
Digital Mode Operation
(
SSB-Based AFSK
)
The
FT-818
provides extensive capability for digital mode operation on the HF, VHF, and
UHF bands. The use of AFSK (Audio Frequency-Shifted Keying) configurations allows a
wide variety of different communication modes to be utilized. The Menu provides for spe-
cific digital mode selections, which include custom BFO offsets to optimize the receive and
transmit passbands for the mode selected.
Before beginning Digital operation, you need to define which Digital mode will be utilized.
To do this, use Menu #26 as follows (in this example, we will set up RTTY as the Digital
mode):
1. Press and hold in the key for one second to enter the Menu mode.
2. Rotate the
knob to select Menu #26 (DIG MODE).
3. Rotate the
knob to select “RTTY”.
4. Press and hold in the key for one second to save the new setting and exit.
Use this technique to set up any digital mode.
RTTY (Radio TeleType) Operation
The “RTTY” mode on the
FT-818
is based on LSB-side carrier injection, in accordance
with long-standing amateur practice. If you need USB-side injection for your application,
see the “User” mode discussion below.
1. Connect your TNC (Terminal Node Controller) or terminal modem to the
FT-818
’s
rear-panel
DATA
jack, per the illustration.
2. Press the
/
key, as needed, to select the DIG mode (the “DIG”
icon will appear on the display). Be certain to use the “TX Audio” line from your TNC,
not an “FSK Key” line, for the transmit-data connection.
3. Press the
/
key, as needed, to select the DIG mode (the “DIG”
icon will appear on the display). You should now be able to tune around the band, and
any RTTY signals heard should be capable of being decoded.
GND
KEY
DATA
ACC
ANT
:
INPUT DC13.8V
PTT
DATA IN
GND
AFSK
OUT AF IN
PTT
DATA OUT
Pin Label
Note
DATA IN
Maximum Input Lebel:
1.0 V pp Impedance: 10 kΩ
PTT
Ground to Transmit
DATA OUT Maximum Output Level:
300 mVpp Impedance: 10kΩ
