Lectrosonics UM400a


Lectrosonics UM400a


The UM400a implements the latest Digital Hybrid Wireless technology in a classic Lectrosonics belt-pack transmitter.

The innovative servo bias input on the standard 5-pin connector provides a programmable, regulated voltage to accommodate a wide variety of electret microphones. The TA5F connector also provides taps for low impedance dynamic mics, electret lavalier mics with positive or negative bias and line level inputs.

Input gain is adjustable over a 43 dB range to perfectly match the audio input level for optimum modulation, minimum distortion and maximum signal to noise ratio. Input levels are accurately indicated by two LEDs on the control panel.

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  • RF Carrier Frequency Range: Block 26 (665.600 - 691.100 MHz)
  • Frequency selection: 256 frequencies in 100kHz steps
  • RF Power output: 100 mW (nominal)
  • Pilot tone: 25 to 32 kHz frequency; 5kHz deviation
  • Frequency stability: ± 0.002%
  • Deviation: ± 75 kHz (max)
  • Spurious radiation: 90 dB below carrier
  • Equivalent input noise: –120 dBV, A-weighted
  • Input level: Nominal 2 mV to 300 mV, before limiting. Greater than 1V maximum, with limiting.
  • Input impedance: Dynamic mic - 300 Ohms, Electret lavalier - Input is virtual ground with servo adjusted constant current bias, Line level - 2.7 k Ohms
  • Input compressor: Dual envelope compressor, >30 dB range
  • Gain control range: 43 dB; semi-log rotary control
  • Modulation indicators: Dual bicolor LEDs indicate modulatio. of -20, -10, 0, +10 dB referenced to full modulation.
  • Low frequency roll-off: –18 dB/octave; 35Hz to 150Hz
  • Audio frequency response (overall system): 35 Hz to 20 kHz, +/-1 dB 
  • Controls: 2 position “OFF-ON” slide switch for noiseless turn on/turn off operation. Front panel knob adjusts audio gain. Recessed control on side panel adjusts low frequency rolloff. Rotary switches on side panel adjust transmitter frequency.
  • Audio Input Jack: Switchcraft 5 pin locking (TA5F)
  • Antenna: Detachable, flexible wire supplied. 50 Ohm port allows connection to test equipment.
  • Power Consumption: 80mA
  • Battery: Precision compartment auto-adjusts to accept any known alkaline 9 Volt battery.
  • Battery Life: 5 hours (alkaline); 10 hours (lithium)
  • Operating Temperature: -20 to +140 degrees F Weight: 6.3 ozs. including battery