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 third lead
is
for transmit/receive control and the fourth lead
is
the speaker return lead which disables the speaker during transmit. The
microphone should provide the functions shown
in schematic below.
4-Wire
Mic
Cable
Pin
Number
2
3
4
Mic
Cable Lead
Audio Shield
Audio Lead
Transmit Control
Receive Control
1/8"
STRIP
a TIN
Fig. l . Microphone cable preparation.
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 7I16" beyond the plastic insulating jacket
of
the
microphone cable. (See Fig. 1.)
10
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