Lectrosonics UM400a - Manual (Page 9)

Frequency Synthesized UHF Belt-Pack Transmitter
Rio Rancho, NM 9
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 oc-
casional red flickers and -10 dB glows green.. This
will set the gain of your transmitter for signal peaks
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 (optimum)
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. Adjust the
receiver output level to match the sound system or
recorder.
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 will need to change the operat-
ing frequency of your system.
If you are using a receiver with a frequency scan func-
tion, find a clear frequency with the receiver, then set
the transmitter to match.
Note: Leave the transmitter turned off while you
search for a clear frequency.
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 increments 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 Lectrosonics Digital Hybrid receivers, a front panel
LCD character display will indicate the correct transmit-
ter 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
1.6 MHz 100kHz