Parts List

Transmitter Main Board Instruction Manual 2-13
Table 3-1 MT-3 Audio Processor Current Consumption.
Function Current Draw
keyed / unkeyed
Switched Audio Standby
Both Microphone and Balanced Input enabled
6.0 / 0.3 mA
Only Microphone or Balanced Input enabled 4.5 / 0.3 mA
Only Auxiliary Input enabled 3.0 / 0.3 mA
Continuous Audio Standby
Both Microphone and Balanced Input enabled
6.0 / 3.5 mA
Only Microphone or Balanced Input enabled 4.5 / 1.5 mA
Only Auxiliary Input enabled 3.0 / 0.5 mA
2.4.3 Audio Processor Turn-on Time
The turn-on time of the audio processor is 25 ms. This measurement is made with the standard
factory settings with a 1 kHz tone applied to the balanced input. The turn-on time is the time it
takes the audio processor to output a stable audio signal from the time its power (+9.5 Vdc) is
switched on. The turn-on time can be virtually eliminated by configuring the audio processor for
continuous audio standby (see section 2.1.2.7 Transmitter Standby Modes).
2.4.4 Audio Processor Signals
The MT-3 Audio Processor has six audio inputs, two audio outputs and one audio control input.
Five of the audio inputs are used primarily for voice signals. The sixth, the Direct modulation input,
is used primarily for data signals. The audio control input is used to switch audio outputs so the
transmitter can transmit voice or data.
2.4.4.1 Audio Processor Outputs
Both the audio outputs, Modulation Output (P3-1) and Low Frequency / Direct Modulation Output
(P4-2), are gated by audio switches U9 and U10 respectively which are controlled by the Tx Audio
Control Input (P4-4). The audio switches operate complimentary to each other so there can ever
only be one source modulating the transmitter. In standard configuration, the Modulati on Output
port is used so switch U9 is always on.