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Combining a compact, stylish design with outstanding coverage and simple setup, the LA-140 IR Radiator/Emitter from Listen Technologies is an expandable option for any infrared assistive listening application.

Two LA-140 units can be mounted together horizontally or vertically, doubling the power of your system without taking up an excessive amount of space. Additionally, two units can be powered by a single LT-82 transmitter or optional power supply with standard CAT-5 cable, making setup and installation simple.

Each unit includes hardware for mounting on wall, ceiling, desk, mic stand or tripod, making the LA-140 an incredibly versatile choice for nearly any IR assistive listening system.

With a compact design and availability in either white (-WH) or grey (-GY), the LA-140 IR Radiator/Emitter from Listen Technologies is a discreet and dependable choice.


One (1) LA-140 Stationary IR Radiator
One (1) Mounting hardware (allows for wall, ceiling, desk, mic stand and tripod mounting)
Twenty-five (25) ft. (7.6 m) of coax cable, matched color
Twenty-five (25) ft. (7.6 m) of CAT-5 cable, matched color
One (1) Quick Reference Card

Up to two LA-140 radiators can be powered by one LT-82. If additional power is required, order an additional power supply.


  • Up to 3,716 m² (40,000 ft.²) of maximum coverage per radiator
  • Two (2) radiators can be combined and powered by a single LT-82 transmitter or optional power supply via standard CAT-5 cabling
  • Can be mounted together horizontally or vertically for double the power in a compact space
  • Automatic radiator diode shutoff feature extends radiator life
  • Delay compensation to eliminate dropout in the infrared signal
  • Available in either white or grey for discrete installation in a variety of settings
Configurations & Architectural Specs


LA-140-GY Stationary IR Radiator -Grey
LA-140-WH Stationary IR Radiator -White

Architectural Specs

The radiator-emitter shall have a single carrier transmitting area of 3,716 m² (40,000 ft.²) for each radiator when used with LR-4200 / LR-5200 receivers. The radiator shall be powered via CAT-5 cabling and the RF from the transmitter shall be carried by 50 ohm coaxial cable. The radiator shall have three indicating LEDs for power, no carrier present and carrier present. The radiator LEDs shall be deactivated after 30 minutes if there is no audio signal present from the transmitter. The radiator shall come in a white or grey color and shall include all of the mounting hardware capable of mounting the radiator on a wall, on a ceiling, in a corner, on a desk, on a mic stand or on a tripod. The Listen LA-140 is specified.

Product Specifications
Specification LA-140


User Controls Termination Switch, Delay Compensation Switch, Indicator LEDs on/off, Compatibility Switch


Red LED Indicates power is present.
Yellow LED Indicates no connection to transmitter or radiator.
Green LED Indicates carrier and power are present and radiator is emitting IR signal.


Frequency Range 1 MHz - 5 MHz
Input/s BNC Connection. -25 dBm to -5 dBm input nominal
Output/s BNC Connection. -15 dBu nominal
Coverage Area 3,716 m² (40,000 ft.²) maximum coverage per radiator when used with LR-4200 / LR-5200 Receivers


Power Supply Input RJ-45 connector. 30 VDC, powered from transmitter via CAT-5 cable or optional LA-205 power supply.
Power Supply Output RJ-45 connector. 30 VDC, powers up to one additional radiator. (Maximum two radiators powered from each LT-82 transmitter or LA-205 power supply)
Emitter Power 3 W
Cable Length 250 ft. with (1) LT-82 and (2) LA-140 or 700 ft. with (1) LT-82 and (1) LA-140.


Width 8.00 in. (203 mm)
Height 5.50 in. (140 mm)
Depth 2.60 in. (66 mm)
Color LA-140-GY (Grey), LA-140-WH (White)
Shipping Weight 6.0 lbs. (2.70 kg)
Mounting Radiator can be mounted on a wall, on a ceiling, in a corner, on a desk, on a mic stand or on a tripod. Wall box mounting plate fits a standard single gang electrical box.
Weight 2.1 lbs. (0.95 kg)
Weight (Loaded) 2.4 lbs. (1.09 kg)


Temperature - Operation -14 °F (-10 °C) to +104 °F (40 °C)
Temperature - Storage -4 °F (-20 °C) to +122 °F (50 °C)
Relative Humidity 0 to 95% relative humidity, non-condensing


Standards FCC Part 15, Industry Canada, CE, RoHS
Used With
Q How much coverage is provided with the LA-140?
A Approximately 10,000 ft² (929 m²).
Q Does the number of audio sources (carriers) affect the coverage?
A Yes, for two (2) sources (carriers), the total coverage is half of 10,000 ft² (929 m²). For four (4) sources (carriers), the coverage per carrier is one-fourth.
Q How many radiators can you use on a system?
A Up to 100.
Q How many radiators will I need?
A Refer to the technical resource section of the Listen website for assistance in making this calculation.
Q Does the LA-140 come with a power supply?
A No, you must use either the power supply included with the LT-82 transmitter or purchase the optional LA-205 power supply.
Q How do I connect multiple radiators?
A You can daisy-chain the radiators together using coax cables. Power for up to two radiators can be daisy-chained using a short length of CAT-5 cabling or you can power two radiators off one transmitter.
Q Can I disable the LEDs on the radiator?
A Yes, the LEDs can be turned off at a switch on the back of the radiator.
Q How many emitting diodes does the LA-140 have?
A The LA-140 radiator has 84 diodes. It has 7 columns of diodes with 12 diodes each. If one diode goes out, you will lose only the diodes on that column.
Q What is the warranty of the LA-140?
A The LA-140 has a 3-year warranty.
Q How is power delivered to the radiator?
A Power is delivered with CAT-5 cables (connected between the radiator and either the LT-82 transmitter or the LA-205 power supply).
Q How many radiators can be powered from the LT-82 or LA-205 power supply?
A Two.
Q What is the purpose of the delay compensation switch?
A This switch allows you to set up delay timing in a multi-radiator system so that each radiator receives the carrier at exactly the same time. This prevents signal dropouts that can be caused by out-of-phase signals (multi-path). With Listen’s delay compensation switch, it is not necessary to cut all of your coaxial cables to the same length - your shorter runs can use shorter cables, keeping your installation clean (and cost-effective).
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