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 a low output impedance characteristic. The microphones must be
provided with a four-lead cable. The audio conductor and its shielded lead
comprise two of the leads. The fourth lead is for receiving control, and the
third is for transmitting control. The microphone should provide the
functions shown in schematic below.
4 WIRE MIC CABLE
Pin Number
Mic Cable Lead
1 Audio
shield
2 Audio
Lead
3 Transmit
control
4 Receive
Control
Fig. 3
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.
Before beginning the actual wiring read carefully, the circuit and wiring
information provided with the microphone you select. Use the minimum
head required in soldering the connections. Keep the exposed wire lengths to
a minimum to avoid shorting when the microphone plug is reassembled.
Fig. 4
Microphone plug wiring
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 Fig. 4.
5. The wires must now be soldered to the pins as indicated in the above
wiring tables. If a vise or clamping tool is available it should be used to
hold the pin receptacle body during the soldering operation, so that both
hands are free to perform the soldering. If a vise or clamping tool is not
available, the pin receptacle body can be held in a stationary position by
inserting it into the microphone jack of the front panel. The numbers of
the pins of the microphone plug are shown in Fig. 5, as viewed from the
back of the plug. Before soldering the wire to the pins, pre-tin the wire
receptacle of each pin of the plug.
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