User's Manual
6
LM400
LECTROSONICS, INC.
CONTROLS AND FUNCTIONS
MIC
The Microplug (2.5 mm) input on the transmitter accommodates 2 wire positive bias lavalieres. This jack will mate with
a Switchcraft 850 plug.
ON/OFF SWITCH
Turns the battery power on and off. Even when the switch is turned off or on abruptly, the pilot tone muting system
prevents “thumps” or transients from occurring.
“ON” LAMP
Glows green when the battery is good and the ON/OFF switch is ON. The lamp will glow yellow/orange as the battery
voltage drops and finally glows red when there is about 30 minutes of operation left with the recommended alkaline
battery. The lamp will flash red when there are only a few minutes of life left. A NiMh battery will give little or no
warning when it is depleted. If you wish to use NiMh batteries in the LM400, we recommend trying fully charged
batteries in the unit, noting the length of time that the batteries will run the unit and in the future use somewhat less
than that time to determine when the battery needs to be replaced. A weak battery will sometimes light the POWER
LED to the “good” green indication immediately after being put in the unit, but will soon discharge to the point where the
LED will go red or shut down, just like a flashlight with “dead” batteries. If the lamp fails to light, the battery should be
replaced.
FREQUENCY ADJUST
These two rotary switches adjust the center frequency of the carrier. The 1.6M is
a coarse adjustment and the 100K is the fine adjustment.
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
1.6M 100K
MODULATION LEDS
Indicate the proper setting of the MIC LEVEL control. There are two bicolor modulation LEDs that can light either red or
green.
“-20dB level” One modulation LED glows green and the transmitter is 20 dB below full modulation.
“-10 dB level” Both modulation LEDs glow green and the transmitter is close to full modulation.
“+0 dB level” The -20 LED glows red and the -10 LED glows green. The transmitter is in slight limiting and is fully
modulated. This is probably desirable. See the discussion below under Input Limiter.
“+10 dB level” Both LEDs are red. The transmitter is in limiting and you may want to reduce the transmitter audio
gain. See the discussion below under Input Limiter.
FREQUENCY
1.6MHz
100kHz
OFF
ON
AUDIO
LEVEL
-10
-20
ANTENNA
MIC
LECTROSONICS
LM400
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