M8SL2-00-002-812 T855 Initial Tuning and Adjustment B3.13
© Copyright Tait Electronics Limited August 2004. All rights reserved.
3.11 Audio Processor
3.11.1 Line Amplifier Output
Apply an on-channel signal from the RF generator at a level of –70dBm with
±3kHz deviation (±2.4kHz) [±1.5kHz] at 1kHz.
Adjust RV210 (front panel line level) to give an output of +10dBm on the 600Ω
line.
Check for any clipping or distortion on the oscilloscope.
Set the line level to the required output level.
3.11.2 Monitor Amplifier Output (Speaker Output)
Adjust RV205 (front panel monitor volume) to give an output of 2V
rms
into a 4Ω
resistive load.
Check for any clipping or distortion on the oscilloscope.
Switch to a 4Ω speaker and adjust RV205 to the required level.
3.12 CTCSS
3.12.1 Decoder Operation
Program a CTCSS tone on the default channel using PGM800Win.
Set the RF signal generator output to –70dBm.
Modulate the generator with both:
• a 1kHz tone at ±3kHz deviation (±2.4kHz) [±1.5kHz]
• and a CTCSS tone at the programmed frequency at ±500Hz deviation (±400Hz)
[±300Hz].
Check that the receiver gate opens and the front panel “Gate” LED is on.
3.12.2 Opening Sinad
Adjust RV230 (front panel gating sensitivity) fully clockwise.
Reduce the RF signal level to –110dBm.
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