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Racket Radio TNC Interconnections
Most popular packet radio tncs can be connected to thè MIC jack of
thè FT-2311R as follows:
TNC Transceiver Jack
Receiver Audio in
Squelch Ctrl
in
PTT (gnd=tx)
out
Transmit Audio out
FT-2311R MIC Jack
pin 4 (8 ohms, de-emphasized)
pin 5* (open=8V, closed=OV 1 mA)
pin 6
pin 8 (400 ohms, pre-emphasized)
Use shielded cable for thè audio lines, and keep thè interconnecting
cable as short as possible to avoid RF pickup.
VERSION A
V E R S I O N
B
MIC r\—
MIC
Q6O5
2SC1623
Modification for Packet Radio
In thè European version (B), pin 5 of thè MIC jack is wired in parallel
with thè T CALL button on thè front panel to accept tone burst acti-
vation from thè microphone. This feature is not needed for packet
radio operation, however, so pin 5 may be rewired to provide output
of thè Squelch detect line for packet radio tncs. In other version
(not equipped with a T CALL button or generator), pin 5 is already
wired this way. The tone burst may stili be activated after this modifi-
cation in European versions, but only by thè T CALL button on thè
front panel.
in thè European version (B), this pin is wired for Burst control
from thè microphone. It can be modified as follows;
(1)
Remove thè ten screws affixing thè top and bottom covers, and
remove thè covers, using care not to strain thè speaker wires.
(2)
Remove thè four screws affixing thè front panel, and gently
separate it from thè chassis, just enough to gain access to
thè CNTL Unit without straining thè wiring.
(3)
Cut thè green wire at pin 5 of thè MIC jack on thè rear of
thè CNTL Unit, and carefully tape thè end of this wire out
of thè way.
(4)
Referring to thè diagram below, connect a 200mm wire between
thè point indicate on thè solder side of thè Main Unit and
pin 5 of thè MIC jack. Route this wire so that it wijl not
interfere with installation of thè covers.
(5)
Replace thè front panel and its four screws,
and then thè
top and bottom covers and their ten screws.
CNTL Unit(lnside front panel)
DH
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