M8SL2-00-002-812 T854 Initial Tuning and Adjustment C3.13
© Copyright Tait Electronics Limited August 2004. All rights reserved.
3.9.5 Line Level Without Compressor
This section assumes that the compressor is not used. If the compressor is required, refer
to Section 3.9.6.
1. Remove the CTCSS signal (if used).
2. Adjust the line sensitivity as follows:
• set the injected signal at the line input to the required line level (typically –10 to
–20dBm)
• adjust RV210 (line sensitivity) to provide ±3kHz (±2.4kHz) [±1.5kHz] deviation
3. Reapply the CTCSS signal (if required).
3.9.6 Compressor
The compressor may be used on the line input only, the microphone input only, or on
both the line and microphone inputs. If the compressor is used, refer to one of the fol-
lowing sections as appropriate.
3.9.6.1 Compressor On Line Input Only
1. Set RV210 (line sensitivity) fully clockwise and key the transmitter by earthing the
Tx-Key line.
2. Reduce the line level to –50dBm at 1kHz and set RV220 (compression level) fully
clockwise.
3. Check that ±3kHz deviation (±2.4kHz) [±1.5kHz] is still available.
4. Slowly increase the audio input level until the demodulated waveform shows sig-
nificant signs of clipping (approximately ±4.5kHz (±3.6kHz) [±2.3kHz] deviation).
5. Adjust RV220 anticlockwise until the demodulated waveform is just clipping
(approximately ±4kHz (±3.2kHz) [±2kHz] deviation).
6. Increase the input level to –10dBm and check that the test tone is still held just into
clipping. The input line level should be typically –10 to –20dBm.
3.9.6.2 Compressor On Microphone Input Only
1. Key the transmitter by earthing the Tx-Key line and plug a microphone jack into
the front panel socket.
2. Adjust RV220 (compression level) fully clockwise.
3. Acoustically couple the microphone to a tone box (1kHz) and close the PTT
switch.
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