Lectrosonics UM190 User Manual download pdf (Page 5)

CONTROLS AND FUNCTIONS (cont’d)

Since the internal circuits are all tightly regulated and the RF output stage has a separate discrete regulator, the

transmitter will continue to operate to a battery voltage of 6.5 Volts. From 6.5 Volts to 6 Volts, the transmitter will

still operate, but with degraded performance. Please note that a weak battery will sometimes light the POWER

LED immediately after turn on, but will soon discharge to the point where the LED will go out, just like a flashlight

with "dead" batteries.

The combination of an accurate battery condition indicator and regulation of all internal circuits provides much

longer battery life, as well as consistent performance over the life of the battery.

MODULATION LEDS

Indicate the proper setting of the MIC LEVEL control.

LEVEL LED -- Flickers or glows when sufficient audio is present.

LIMIT LED -- Lights up when the input level is high enough to cause limiting. The input limiter has a very

high overload threshold (over 40 dB). Generally speaking, some limiting is desirable in normal operation to

improve the signal to noise ratio of the system. The limiting action is not audible and does not create

distortion. A highly trained ear would hear only the compression of the peaks in the audio signal, which is

desirable with most tape recorders and many sound reinforcement systems.

MIC LEVEL

Used to adjust the audio input level for the proper modulation.

ANTENNA

The flexible wire antenna supplied with the UM190 UHF transmitter is cut to 1/4 wavelength. It is removable via a

twist lock connector. The 50 Ohm RF port can also be connected directly to test equipment.

ADJUSTABLE LOW FREQUENCY ROLL-OFF

A 6dB/octave low frequency roll-off is provided in the audio section, with the -3dB point adjustable

from 30Hz to 150Hz.

THE BELT CLIP

The belt clip may be removed for special applications by removing one screw.

USE ONLY THE SCREW THAT IS SUPPLIED

The circuitry is tightly packed into this unit. A longer screw will permanently damage the transmitter!

50 Ohm

Antenna Port

Figure 3 - UM190, UHF Antenna Location

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Lectrosonics UM190 User Manual Page 5