454 TMAA01-01 Line-Interface Board TM8100/TM8200 Service Manual
© Tait Electronics Limited June 2006
2. Set the DIP switches on the line-interface board (S1) to the following
default test settings:
■ DIP1 on (two-wire audio interface)
■ DIP2 off
■ DIP3 off
■ DIP4 on (busy/gate = rx-gate)
■ DIP5 on (busy/gate logic active high)
■ DIP6 off
■ DIP7 off (two-wire keying)
■ DIP8 off (time delay disabled).
Disassemble the radio in order to gain access to the options cavity. For
detailed disassembly instructions, refer to “Disassembly and
Reassembly” on page 129.
3.
Note When installing the internal options loom, take care that it is
folded in the way shown in Figure 17.2.
Connect the internal options loom between SK2 on the line-inter-
face board and SK102 on the radio’s main PCB.
4. Set up the test equipment shown in
Figure 17.1
, and follow the
adjustment procedure for RV1, RV2 and RV3 described in the following
section.
17.2.4 Adjusting RV1, RV2 and RV3
Setting the Keying
Time Delay (RV1)
The keying time delay circuit is used to prevent the burst of noise occurring
before a mobile is able to mute the audio when the carrier signal disappears.
The keying time delay is used in conjuction with the keying signal
(SK1 pin 1).
Set DIP8 on, and adjust RV1 for the required time delay. Rotate RV1
clockwise to increase the delay, and counterclockwise to reduce the delay.
Table 17.3 Line-interface settings in the Programmable I/O form, Audio tab
Rx/PTT Type Tap In Tap In Type Tap In Unmute Tap Out Tap Out Type Tap Out Unmute
Rx None A-Bypass In On PTT R7 D - Split Busy Detect
EPTT1 T5 A-Bypass In On PTT None C-Bypass 0 On PTT
Table 17.4 Line-interface settings in the PTT form, External PTT (1) tab
Field Setting
Advanced PTT PTT Transmission Type Voice
Audio Source Audio Tap In
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