The UM400a implements the latest Digital Hybrid Wireless® technology in a classic Lectrosonics belt-pack transmitter.
A 5-pin input jack 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.
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 latest digital/analog hybrid technique is presented
in a classic Lectrosonics wireless belt-pack transmitter. 24-bit digital audio is combined with optimized FM to cre- ate unprecedented audio quality and RF performance. The RF transmission is an aggressively optimized FM system with +/-75kHz wide deviation for a high signal to noise ratio. The overall system delivers full bandwidth audio frequency response up to 20kHz and the operating range of the finest analog wireless systems.
The innovative servo bias input on the standard 5-pin connector provides a programmable, regulated voltage to accommodate a wide variety of electret microphones. It is no longer necessary to install resistive pads for some mics to prevent overload of the input stage, divide the bias voltage down for some low voltage mics, or reduce the limiter range at minimum gain settings. To simplify wiring connectors, a single configuration for all microphones is now available for the UM400a transmitter input, and an alternate wiring configuration works well with all 5-pin inputs on Lectrosonics transmitters.
Compatibility with earlier analog Lectrosonics receivers and even some receiver models from other manufactur- ers is provided by custom firmware emulations built into the DSP code. A simple procedure using the frequency and power switches selects the desired operating mode.
Operating Frequencies (MHz):
Block 470: 470.100 - 495.600
Block 19: 486.400 - 511.900
Block 20: 512.000 - 537.500
Block 21: 537.600 - 563.100
Block 22: 563.200 - 588.700
Block 23 lower: 588.800 - 607.900
Block 23 upper: 614.100 - 614.300
Block 24: 614.400 - 639.900
Block 25: 640.000 - 665.500
Block 26: 665.600 - 691.100
Block 27: 691.200 - 716.700 (export only)
Block 28: 716.800 - 742.300 (export only)
Block 29: 742.400 - 767.900 (export only)
Block 944: 944.100 - 951.900
256 synthesized UHF frequencies
100 mW output power
DSP controlled dual envelope input limiter
DSP emulations for analog compatibility
Servo bias input preamp
DSP based pilot-tone signal
Circulator/Isolator output stage
Adjustable low frequency roll-off
Frequency selection: 256 frequencies in 100kHz steps
RF Power output: 100 mW (nominal)
Pilot tone: 25 to 32 kHz; 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 lavaliere: Input is virtual ground with servo adjusted constant current bias, Line level: 2.7 k Ohms
Input limiter: Dual envelope "soft" limiter; greater than 30 dB range
Gain control range: 43 dB; semi-log rotary control
Modulation indicators: Dual bicolor LEDs indicate modulation of
-20, -10, 0 and +10 dB referenced to full modulation
Audio Performance (overall system) Frequency Response: 32 Hz to 20 kHz (+/-1dB)
THD: 0.2% (typical)
SNR at receiver output:
Controls: Two position "ON-OFF" power switch, Audio input gain knob, Low frequency roll-off pot on side panel, Two 16-position rotary switches adjust frequency