Lectrosonics UM400 - Manual (Page 11)

Frequency-Agile UHF Belt-Pack Transmitter
Attaching a Microphone and Adjusting Gain
1) Ensure the battery is in good condition.
2) Insert the microphone plug into the input jack, align­
ing the pins; be sure that the connector locks.
3) Attach the antenna to the SMA connector on the
top of the transmitter.
4) Mute the associated receiver’s audio output.
5) Turn on the transmitter.
6) Position the microphone in the location you will
use in actual operation. While speaking or singing
at the same voice level that will actually be used,
observe the Modulation LEDs. Adjust the AUDIO
LEVEL control until the –20 dB LED glows green
with occasional red flickers and -10 dB glows green.
This will set the gain of your transmitter to between
+0 dB and +10 dB modulation. (See chart below.)
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
7) Once the gain has been adjusted, the audio system
audio can be turned on to make level adjustments
in the main audio system.
NOTE: The transmitter Audio Level Control should
not be used to control the volume of your sound
system or recorder levels. This gain adjustment
matches the transmitter gain with the user’s voice
level and microphone positioning.
Operating Notes
If the audio level is too high — both LEDs will blink red
frequently or glow a steady red. This condition may
reduce the dynamic range of the audio signal.
If the audio level is too low — neither LED will glow, or
only the -20 LED will glow green. This condition may
cause hiss and noise in the audio.
Different voices will usually require different settings of
the AUDIO LEVEL control, so check this adjustment as
each new person uses the system. If several different
people will be using the transmitter and there is not time
to make the adjustment for each individual, adjust it for
the loudest voice.
Adjusting the Transmitter Frequency
If you are experiencing interference from another
signal on your frequency, you may want to change the
operating frequency of your system. The left switch
changes the operating frequency by 1.6 MHz per step
and the right switch changes it 100 kHz per step. Start
by changing the operating frequency in 100 kHz incre­
ments to find a clear channel. If it is not possible to find
a clear channel using the 100 kHz switch, return it to its
original position and change the 1.6 MHz switch by one
click then try the 100 kHz switch again.
To gain access to these switches, slide the access door
sideways with a fingernail.
With the 400 Series receivers, a front panel LCD char­
acter display will indicate the correct transmitter switch
settings.
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
Rio Rancho, NM 11