Afsk Tnc Connections - Yaesu FT-847 Operating Manual

Installation

AFSK TNC Connections

(for HF RTTY and Packet, etc.)
The FT-847 is easy to connect to most all Terminal
Node Controllers (TNCs) or other digital modem units
used for RTTY, HF Packet, and other digital modes
utilizing either USB or LSB.
Audio Frequency-Shifted Keying (AFSK) operation
for HF Baudot, AMTOR, 300 bps Packet, etc. is pro-
vided via the rear-panel DATA IN/OUT terminal.
The tip connector of this jack accepts "TX Audio"
from the TNC; the optimum level is 20 mV at 10 k
impedance. The ring connector provides "RX Audio"
from the FT-847's receiver. This is fixed-level audio
200 mV at 10 k , not affected by the setting of the
front panel's AF control.
The other connection required for AFSK operation is
PTT control of the transceiver's transmit/receive sta-
tus. Use the illustration below to connect the TNC's
PTT line to the DATA IN/OUT terminal.
Note: If you use the rear-panel's "PTT" jack for AFSK
operation, the transceiver will operate in the "SSB"
mode, with the microphone connected. Activating PTT
via the DATA IN/OUT jack disconnects the micro-
phone.
16
A I
CCESSORY NTERFACING
Typical connection information is presented below.
Caution!
Some digital modes, such as RTTY (Radio
TeleType), require continuous key-down trans-
mission. While the internal fan is designed to
protect your transceiver from excessive heat, full
key-down output for long periods is not recom-
mended. Especially during hot or humid
weather, we recommend minimizing continuous
full-power transmit time to ensure long life of
the transceiver components, with a three-minute
maximum being recommended (with a five
minute "rest" period thereafter).
If possible, adjust the transmit audio input level
to restrict the power output to 50 Watts or less
on HF, 25 Watts or less on 144/430 MHz, if
longer transmissions (and/or shorter "rest" pe-
riods) are required.
FT-847 O M
PERATING ANUAL