M8SL2-00-002-812 Installation and Configuration D3.13
© Copyright Tait Electronics Limited August 2004. All rights reserved.
The table above shows that configuring LN8 with links 2–3 and 4–5 could be used for
systems with or without CTCSS. Configuring LN8 with link 1–2 in normally only used
with systems without CTCSS on the Rx audio.
Procedure
Before commencing this procedure set up the receiver audio processing, such as de-
emphasis and CTCSS filtering, as required for the application. See Section 3.5 in Part B.
This is important for the T803 Telecom line compliance. See the Caution below.
CAUTION: The Rx audio level must not exceed 230mV
rms
at 60% full system devia-
tion. This will ensure that the actual T803 Line-Out level corresponds
to the programmed value and thus ensures levels do not exceed the
power level requirements of the Telecommunications line.
There are three possible ways to monitor the Rx Audio level during adjustment:
• Direct measurement of receiver audio on the backplane
• Indirectly, using transmitter deviation
• Indirectly, using the T803 Line-Out level
Direct measurement of receiver audio on the backplane:
1. Use the RF Test Set to generate an on-channel signal to un-mute the receiver.
2. Modulate the RF carrier with a 1020Hz tone
1
at 60% full system deviation, adding
CTCSS tone for a CTCSS system (ensure that CTCSS filtering is applied in the
receiver as required for the application. See Section 3.5 in Part B).
3. Monitor the audio level from the receiver on the X800-56-PCB3 backplane at pin2
of LN8, with the links (jumpers) in place as directed in Section 3.1.1. Use a high
impedance meter such as an oscilloscope for the measurement.
Receiver/T803
system
Backplane
links (LN8)
Adjustment of Rx
Audio to T803
Audio Frequency Response
With CTCSS on
Rx audio
Link pins 2–3
and pins 4–5
Line Level control on the
front of the Receiver
Receiver internal CTCSS filter should
be included in the path (see Section
3.5 in Part B)
400Hz to 3kHz
No CTCSS on Rx
audio
Link pins 2–3
and pins 4–5
Line Level control on the
front of the receiver
Receiver internal CTCSS filter not in
path but high pass filter in path (Rx
default setup)
220Hz to 3kHz
No CTCSS on Rx
audio
Link pins 1–2 RV2 on the backplane T803 high pass filter only
160Hz to 3kHz
1. A 1020Hz tone is used (rather than 1kHz) because some Test Sets can produce unstable
deviation readings
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