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RF Technology R50
1.1.4 C.SQ
The C.SQ trimpot is used to set the carrier squelch sensitivity. Carrier squelch is
useful at higher signal levels than noise squelch and can be used from 1 - 200
uV input.
It is provided mainly for use in fixed link applications where a high minimum signal
to noise ratio is required or where very fast squelch operation is required for
data transmission. The carrier squelch will open and close in less than 2 mSec.
In most base station applications carrier squelch is disabled by turning the adjustment
counter clockwise until the screw clicks.
The carrier squelch may be set to a predetermined level with the WinTekHelp
software or by using the following procedure:
(a) First turn the adjustment fully counter-clockwise. Then set the noise squelch as
above.
(b) Connect a source of an on channel signal with the desired threshold level to the
receiver's RF input.
(c) Turn the screw clockwise until the SQ LED goes OFF. Then turn the screw back
until the LED just comes ON.
1.1.5 LINE
The LINE trimpot is used to set the line and direct audio output levels. It is normally
set to output 0dBm on the Line output when the carrier is modulated with a
1kHz audio signal at 60% of maximum deviation. NB that 0dBm is equivalent
to 774 mV to an open circuit, or 387mV into a 600 ohm load.
1.2 Fr ont Panel Indicator s
1.2.1 PWR LED
The PWR LED shows that the dc supply is connected to the receiver and that the
microprocessor is not being held in a RESET state.
1.2.2 SQ LED
The SQ LED comes on when the audio to the line and direct outputs is un-squelched.
The LED and squelch function are controlled by the external squelch input, and/or the
noise, carrier, tone, or DCS squelch circuits.
1.2.3 ALARM LED
The ALARM LED can indicate several fault conditions if they are detected by the self
test program. The alarm indicator shows the highest priority fault present.
See Table 1.
LED Flash Cadence
Fault Condition
5 flashes, pause
Synthesizer unlocked
4 flashes, pause
Tuning volts out of range
3 flashes, pause
Low RSSI
2 flashes, pause
The current channel is not programmed or the frequency
