Lectrosonics MM400c - Manual (Page 9)

Watertight Miniature UHF Belt-Pack Transmitter
Rio Rancho, NM 9
Mic Jack
The Mic Jack is a 2.5 mm microplug that is wired to ac-
commodate two-wire positive bias lavalieres. While the
M152-WP (waterproof) is specifically designed for the
MM400C, other two-wire lavaliere microphones can be
adapted to the MM440C using the WPMC-3 or WPMC-
10 kits. A Switchcraft 850 connector (Lectrosonics P/N
21357) can be used in an emergency though it is not
waterproof. (See Replacement Parts and Accessories.)
The equivalent input circuit wiring for the Mic Jack is
shown below:
Audio Level
The Audio Level Control is used to adjust the audio
input level from the microphone for proper modulation of
the output signal from the transmitter.
Modulation LEDs
The two bicolor Modulation LEDs provide a visual
indication of the audio signal level input from the mi-
crophone. These LEDs can glow either red or green
to indicate modulation levels as shown in the following
chart.
Signal Level -20 LED -10 LED
Less than -20 dB Off Off
-20 dB to -10 dB Green Off
-10 dB to +0 dB Green Green
+0 dB to +10 dB Red Green
Greater than +10 db Red Red
When the Power ON/OFF Switch is configured for
Audio Mute Mode, the -10 Modulation LED is also used
to indicate if the transmitter is in an audio muted, or an
unmuted condition. In Audio Mute Mode, if the Power
ON/OFF switch is set to OFF, the transmitter remains
powered up; however, the audio is muted and the -10
Modulation LED blinks green.
If the Power ON/OFF switch is set to ON and the switch
is configured for Audio Mute Mode, -10 and -20 LEDs
operate normally to indicate audio level.
Mic
Jack
330pF 330pF
FB
FB
100
2k
2k
30uF
6V Mic Bias
To Mic Amp
2k
2.2nF
Frequency Select Switches
1.6M 100K
0 1
2
3
4
5
6
7 8 9
A
B
C
D
E
F 0 1
2
3
4
5
6
7 8 9
A
B
C
D
E
F
Frequency Select Switches
Two 16-position rotary Frequency Select Switches are
used to select the operating frequency, for setting Com-
patiblity Modes and for configuring the Power ON/OFF
switch.
The switches are accessed by loosening the retaining
screw holding the cover plate, lifting the cover away
from the housing and rotating it to expose the switches.
For setting the operating frequency, the left switch
(1.6MHz) adjusts the operating frequency up or down in
1.6 MHz increments. The right switch (100kHz) ad-
justs the frequency up or down in 100 kHz increments.
(See Operating Instructions, Adjusting the Transmitter
Frequency.)
A sequence of Frequency Select Switch settings and
Power ON/OFF toggles are used to set Compatibility
Modes and for configuring the Power ON/OFF switch.
(See Operating Instructions, Setting Compatibility
Modes and Power Switch Function Selection.)
Antenna
The permanently-mounted, flexible steel cable antenna
is cut to 1/4 wavelength of the center of the frequency
block (the frequency range) of the transmitter.
Belt Clip
The belt clip may be removed for special applications
by gently spreading the spring wire clip and pulling
the ends out of the holes in the case. The clip can be
installed in either the up or down position so that when
the transmitter is worn, the antenna can be pointing up
or down. Replacement belt clips are available. (See
Replacement Parts and Accessories.)