Specifications

17
F. MODEL 141 MICPLEXOR
1. Description
The Model 141 Micplexor is basically a microphone commutator. It is designed to accept
the outputs from three dynamic microphones, amplify their signals to line level, and scan
them at a rate determined to minimize the
"aliasing"
effect so as to present a spatial
average of the sound field to the Model 140 Sound Analyzer. The output of the
Micplexor is at a high level so that the signal may be transmitted to the Model 140 via a
simple line pair. The scan rate is approximately three times per second. The unit is
battery powered for ease of remote operation.
2. Controls
a. Microphone Inputs
The input to the Micplexor is through three standard microphone connectors, type
XLR-
3-31,
located on the front panel. The inputs are transformer coupled and are designed for
any typical dynamic microphones with an impedance of 150 to 200 ohms. Pin 1 is shield;
pins
2
and
3
are balanced signal input.
b. Level Controls
Each of the microphone inputs to the Model 141 may be adjusted over a 6dB range by the
slide potentiometers on the front panel. This allows adjustment for slight sensitivity
differences between microphones. When each of the slide pots are all the way to the top
of their travel, the gain of each of the input amplifiers is the same.
c. Power
Power is supplied to the Micplexor from two nine volt transistor type batteries,
NEDA
number
1604.
A pair of these batteries will normally supply up to 25 hours of operation.
The unit is turned on and off via the slide switch marked
POWER
on the front panel.
d. Battery Check
The
BATT TEST
slide switch on the front panel tests the condition of the internal
batteries when moved to the
ON
position. If the
LED
on the front panel lights in the
ON
position, the batteries have adequate strength to operate the instrument. If the
LED
fails
to illuminate, the batteries need to be replaced. The circuitry of the Model 141 is
disconnected in the
ON
position, and the unit will only function when the
BATT TEST
switch is in the
OFF
position.