Parts List

2-4 Transmitter Main Board Instruction Manual
intended only as a guideline. Refer to the instruction manual for the transmitter that came with
your system for specifications.
• MODE 1: Jumper J6 out
- the audio processor is switched by a PTT signal
- the synthesizer or crystal controlled oscillator is switched by a PTT signal
- standby current: Synthesized - typically 7 mA
Crystal Controlled - typically 6 mA
- start-up time: Synthesized - typically 50 ms
Crystal Controlled - typically 25 ms
• MODE 2: Jumper J6 in, jumper J7 in the 'y' position, jumper J18 in the 'x' position
- the audio processor is switched by a PTT signal
- the synthesizer or crystal controlled oscillator is enabled all of the time
- standby current: Synthesized - typically 65 mA
Crystal Controlled - typically 25 mA
- start-up time: Synthesized - typically 25 ms
Crystal Controlled - typically 25 ms
• MODE 3: Jumper J6 in, jumper J7 in the 'x' position, jumper J18 in the 'y' position
- the audio processor is enabled all of the time
- the synthesizer or crystal controlled oscillator is switched by a PTT signal
- standby current: Synthesized - not used in this mode
Crystal Controlled - typically 28 mA
- start-up time: Synthesized - not used in this mode
Crystal Controlled - typically 10 ms
• MODE 4: Jumper J6 in, jumper J7 in the 'x' position, jumper J18 in the 'x' position
- the audio processor is enabled all of the time
- the synthesizer or crystal controlled oscillator is enabled all of the time
- standby current: Synthesized - typically 90 mA
Crystal Controlled - typically 46 mA
- start-up time: Synthesized - typically 10 ms
Crystal Controlled - typically 10 ms
2.1.3 Audio Circuits
All of the audio signal co nditioning (e.g. limiting, filtering, and pre-emphasis) is performed by the
MT-3 Audio Processor. The transmitter board routes the audio lines from the backplane connector
to the audio processor and then to the synthesizer. The audio lines routed to the audio processor
are: two subtone inputs (backplane pins B22 and Z24), a direct modulation input (pin Z28), a
squelched/flat audio input (pin Z20), a 600 ohm balanced input (pins B18 and Z18), and an audio
control line (pin Z22). The audio processor's balanced input pins are isolated from pins B18 and