Attaching A Microphone And Adjusting Gain; Operating Notes; Adjusting The Transmitter Frequency - Lectrosonics um400a Instruction Manual

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 sing-
ing 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
Less than -20 dB
-20 dB to -10 dB
-10 dB to +0 dB
+0 dB to +10 dB
Greater than +10 dB
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.
Rio Rancho, NM
-10 LED
Off Off
Green Off
Green Green
Red Green (optimum)
Red Red
Frequency Synthesized UHF Belt-Pack Transmitter

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 the frequency selected with the re-
ceiver. Simply change frequencies to one where no RF
is indicated on the receiver.
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 400 Series receivers, a front panel
LCD character display will indicate the correct transmit-
ter switch settings once a clear frequency has been
located with the scan function (if the receiver is so
equipped).
0 1 0 1
F F
E 2 E 2
D 3 D 3
C C
4 4
B 5 B 5
A 6 A 6
9 7 9 7
8 8
1.6M 100K
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