Service Manual

A1
Page
5.9
6 ~ CIRCUIT DIAGRAMS
TNM-M-E-0012 Issue 1.23
5.2.3.4 Mute/Audio Balance Adjustment
Note. This adjustment has default setting of 1000/2600 and should not need changing except for specific
requirements.
1.
Select the
Mute/TCXO
page and select
Open Mute.
2. Set the RF signal generator to the receiver alignment frequency, and adjust the RF level such that the
desired mute opening SINAD (typically 10dB SINAD) is achieved.
3.
Select
Mute Closed
and remove the RF input from the radio
.
4.
Select the
Mute/TCXO
page
5.
Set the
Squelch Open
and
Squelch Close
sliders to the fully left position. This ensures the receiver
will be muted.
6.
Set the
Squelch Close
slider to the fully right position.
7. Reconnect the RF input to the radio.
8.
Adjust the
Squelch Open
slider to the right until the mute opens.
9. Reduce the Signal Generator output level by approximately 2dB (or by an amount equal to the
desired mute hysteresis level).
10.
Adjust the
Squelch Close
slider to the left until the mute closes.
11. The mute should now open and close at the desired RF levels.
12. Unsquelch the radio and set the radio volume to minimum.
13. Monitor the DC voltage across the speaker or load.
14.
Adjust the
Rx Audio Balance
DAC to achieve a minimum in the measured DC voltage (within
0V±10mV) and leave at this setting.
15.
Note. On revision 2 radios and higher, an additional
Tx Audio Balance
DAC is also provided
.
For these radios, the
Tx Audio Balance
DAC is defaulted to zero for normal setting. However, for a
more accurate setting, the DC voltage at TP731 needs to be noted during Rx and adjusted by the
Tx
Audio Balance
DAC to give the same reading (to within 10mV).