B3.14 T855 Initial Tuning and Adjustment M8SL2-00-002-812
© Copyright Tait Electronics Limited August 2004. All rights reserved.
Observe the sinad meter and reduce the RF level until the receiver mute closes.
Slowly increase the signal level until the receiver mute just opens and stays open.
With PL240 pins 1 and 2 linked (G – H; high pass filter bypassed), check that the
sinad is less than 6dB.
Reset the signal generator for the required opening sinad, adjust RV230 fully anti-
clockwise, then clockwise until the mute just opens.
3.12.3 High Pass Filter
Set the audio processor links as follows:
Reset the RF signal generator output to –70dBm and note the line level (measure-
ment A).
Reduce the 1kHz generator to zero output and measure the line level again (meas-
urement B).
Check that measurement B is at least 30dB below measurement A.
3.13 RSSI
The T800-04-0000 RSSI is an optional PCB which adds signal strength monitoring and
high level mute facilities to the basic receiver.
Ensure the T800-04-0000 PCB is fitted in SK320 and SK330 in the IF compartment.
Align the receiver as instructed in Section 3.6 and Section 3.7.
Apply an on-channel signal from the RF generator at a level of –110dBm with
±3kHz deviation (±2.4kHz) [±1.5kHz] at 1kHz.
Adjust RV320 (RSSI level) to give 2.0V RSSI output on pin 5 of D-range 1 (PL100)
when measured with a high impedance DMM.
Plug Link Function
PL210 1 – 2A – B de-emphasised response
PL230 2 – 3N – P audio from internal CTCSS speech filter
PL240 4 – 5K – L audio input via PL230 or I/O pad
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