C3.14 T854 Initial Tuning and Adjustment M8SL2-00-002-812
© Copyright Tait Electronics Limited August 2004. All rights reserved.
4. Increase the audio level until the demodulated waveform shows significant 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 audio level by 10dB and verify that the test tone is held just into clip-
ping.
7. Whistle steadily into the microphone, checking that approximately ±4kHz
(±3.2khz) [±2kHz] deviation is produced. The modulated waveform should be
basically sinusoidal.
8. Speak into the microphone, checking that the modulation peaks reach about
±5kHz (±4kHz) [±2.5kHz] deviation.
9. As the line is to be used without compression, set RV210 (line sensitivity) as
described in Section 3.9.5.
3.9.6.3 Compressor On Both Line and Microphone Inputs
Set up as described in Section 3.9.6.1.
3.10 Power Alarms (if used)
When fitted to the T854 transmitter an alarm board monitors the transmitter output
power and generates a low forward-power and/or high reverse-power alarm as appro-
priate.
This is achieved by monitoring the output voltages of the transmitters forward and
reverse power directional coupler. A comparison between these voltage levels and user
defined reference voltages generates alarm conditions accordingly. The low forward
power output signal is also gated with the Tx-enable input to ensure that no alarm is
generated when the transmitter is not transmitting. The high reverse power alarm out-
put is not gated. The alarm signal is output on the T854 Aux D-range.
There are two alarms boards currently available, the recently introduced and improved
T800-10-0520 Tx-Alarm/Channel Select board and the older T1500-52-0000, which it
replaces. The alarm outputs of both the these boards are compatible with the
T1511-20-0000 CCM module and the T803-02 Tone Remote and Alarm interface.
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