Operating instructions

8 1892 1344 - SX450G Transceiver Operator Guide v1.7 / Nov 2007
PL1-12 PL1-12 CS5 channel select input
(MSB)
PL1-13 - not connected -
PL2-1 PL1-14 RF DET TX RF present flag
output
HIGH (+5V, internal 10K pull-up) = TX RF
present
LOW (0V) = no TX RF
NOTE: only available when high TX RF power is
selected
PL2-2 PL1-15 AF O/P receiver audio output 600mV p.p. nom. into 10K; AC-coupled; Rout =
2K3.
PL2-3 PL1-16 SQO squelch flag output NPN open collector via 470O; ON = no signal,
OFF = signal present.
(NOTE: OFF when transceiver in standby mode)
PL2-4 PL1-17 OOL out-of-lock output NPN open collector via 470O; ON = out of lock
(NOTE: OFF when transceiver in standby mode)
PL2-5 PL1-18 DMOD digital modulation
input **
+3V to +12V square wave, DC-coupled
** DMOD and AMOD may not be used
simultaneously. Leave unused input
unconnected.
PL2-6 PL1-19 AMOD analogue modulation
input **
750mV p-p., AC-coupled (pre-settable 200mV to
3V p-p.)
** DMOD and AMOD may not be used
simultaneously. Leave unused input
unconnected.
PL2-7 PL1-20 RSSI 'S' meter output 0V to +3V output, rising with received signal level
(typ. 50dB range)
PL2-8 PL1-21 SQOR squelch override input HIGH (>+2.0V) enables AF O/P regardless of
squelch state (RX only)
LOW (+0.8V or o/c) = normal operation
(internal pull-down, 70K to 0V)
POWER SUPPLY AND CURRENT CONSUMPTION
The SX450G requires a power supply of 5V to 15V DC (7.2V DC nominal). Because the
circuitry includes switched-mode power supplies, the current consumed varies inversely
with input voltage, and the external power supply must be capable of supplying the
corresponding current shown in the table below.
Input
State
5V 7.2V 12V
RX 45mA 30mA 25mA
TX 5mW 45mA 30mA 25mA
TX 500mW 400mA 250mA 200mA
Table 1 - Maximum supply current for various input voltages
Note: Connection to a vehicle supply without proper external transient suppression can
cause the internal configuration data to be corrupted.