User's Manual
6
CONTROLS AND FUNCTIONS
INPUT JACK
The input on the UM400 accommodates virtually every lavaliere, hand-held or shotgun microphone available. Line level
signals can also be accommodated. Use a Switchcraft TA5F connector on the cord. See the separate sheet titled
“Transmitter 5-Pin Input Jack Wiring” regarding the correct connections for various microphones, and other
sources.
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. When the lamp glows red, 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 MM400, 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.
LF ROLL-OFF
ADJUST
FREQUENCY
1.6M
100K
FREQUENCY
ADJUST
ANTENNA
OFF ON
–20
0
LECTROSONICS
LEVEL
AUDIO
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
LF ROLL OFF
35 150
75 Hz
UM400
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” One Led is red and the other is 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.