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 receive control, and the third is for transmit 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. 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.
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. 2
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. 2.
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. 3, 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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