Lectrosonics UM300b User Manual download pdf (Page 9)

Frequency Agile UHF Belt-Pack Transmitter

6) Position the microphone in the location you will use in actual operation.

7) While speaking or singing at the same voice level that will actually be used, observe the MODULATION LEDs.

Adjust the AUDIO LEVEL control knob until the LEDs begin to light. Start at a low setting where neither LED

lights as you speak. Gradually, turn the gain up until one LED lights, then the other.

The -20 LED lights when the audio level is about 20dB below full modulation. The “0” LED lights when the limiter

begins to operate. There is over 30dB of limiting range without overload above the “0” LED, so it is desirable that

the it lights up occasionally during use.

8) Once the gain has been adjusted, the audio system audio can be turned on to make level adjustments. Set the

power switch to the ON position and adjust the receiver and/or sound system level as required. Please note,

there will be a delay between the moment the switch is thrown and the time when audio will actually

appear at the receiver output. This intentional delay eliminates turn on thumps, and is controlled by the pilot

tone squelch control.

OPERATING NOTES

The AUDIO LEVEL control knob 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.

If the audio level is too high — both LEDs will light frequently or stay lit. This condition may reduce the dynamic

range of the audio signal.

If the audio level is too low — neither LED will light, or the -20 LED will light dimly. This condition may cause hiss and

noise in the audio, or pumping and breating in the background noise.

The first LED turns on 20dB below full deviation. The “0” LED turns on at full deviation and indicates that the input

shunt compressor is operating. The input limiter will handle peaks over 30dB above full modulation, regardless of the

gain control setting. The limiter uses a true absolute value circuit to detect both positive and negative peaks. The

attack time is 5 milliseconds and the release time is 200 milliseconds. Occasional limiting is desirable, indicating that

the gain is correctly set and the transmitter is fully modulated for optimum signal to noise ratio.

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 (COARSE) changes the operating frequency by larger increments and the

right switch (FINE) changes it in small increments per step. These steps are determined by the programming in the

unit. Refer to the chart of settings provided with the unit. If you are experi-

encing interference, change the operating frequency in FINE steps to find a

clear channel. If it is not possible to find a clear channel using the FINE

switch, return it to its original position and change the COARSE switch by

one click then try the FINE switch again.

To gain access to these switches, slide the access door sideways with a

fingernail.

With the UCR300 receiver, the front panel LED character display will indicate the correct transmitter switch settings.

Rio Rancho, NM – USA

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Lectrosonics UM300b User Manual Page 9