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ALTERNATE MICROPHONES AND INSTALLATION
For best results, the user should select a low-impedance dynamic type microphone or
a transistorized microphone. Transistorized type microphones have low output
impedance characteristics. The microphones must be provided with a four-lead cable.
The audio conductor and its shielded lead comprise two of the leads. The third lead is
for transmit control and fourth is for receiving control.
The microphone should provide the functions shown in the schematic below.
4 WIRE MIC CABLE
Pin Number
Mic Cable Lead
1 Audio
Shield
2 Audio
Lead
3 Transmit
Control
4 Receive
Control
Fig. 1
Your transceiver microphone schematic.
If the microphone to be used is provided with pre-cut leads, they must be revised as
follows.
1. Cut leads so that they extend 7/16" beyond the plastic insulating jacket of the
microphone cable.
2. All leads should be cut to the same length. Strip the ends of each wire 1/8" and tin
the exposed wire.
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Before beginning the actual wiring, read carefully the circuit and wiring information
provided with the microphone you select. Use the minimum heat required in soldering
the connections. Keep the exposed wire lengths to a minimum to avoid shorting when
the microphone plug is reassembled.
Fig. 2
Microphone plug wiring
To wire the microphone cable to the plug provided, proceed as follows:
1. Remove the retaining screw.
2. Unscrew the housing from the pin receptacle body.
3. Loosen the two cable clamp retainer screws.
4. Feed the microphone cable through the housing, knurled ring and washer as shown
Figure 2.
