Infrared Transmitter 2.3/2.8 MHz

Product Highlights

  • Now features improved range - up to 12,000 sq. ft.*
  • Phoenix Contact® connector audio inputs
  • Meets ADA accessibility guidelines
  • Looks great! Sleek, professional styling complements room aesthetics.
  • Front cover can be painted to match décor.
  • 5-year warranty


The WIR TX75 C Infrared transmitter ensures participants in your conference room, courtroom, classroom or other mid-sized venue receive direct, clear communication of your message without sacrificing security. The sleek and stylish TX75 C is designed to maximize coverage area - now up to 12,000 square feet* in single-channel mode when using the RX22-4 receiver. Two slaves (WIR TX75 S) can be added for additional coverage up to 12,000 square feet each (36,000 sq. ft. total), when mounted up to 100 feet from the master transmitter. Placing additional slaves in the same room increases coverage and enhances freedom of movement. A single CAT-5 cable carries both power and signal to slaves–truly a one-cable connection. Mounting bracket and power supply are included.

Note: This new series has Phoenix Contact® connectors and improved range.

*Operating range varies based on receiver used.  See emitter specifications for coverage area by receiver type.

System Includes

(1) WIR TX75 C Infrared Transmitter operating on 2.3/2.8 MHz

(1) BKT 024 wall / ceiling mounting bracket

(1) TFP 046 power supply

(1) WLC 004 main power cord (U.S.)


  • Now features improved range - up to 12,000 sq. ft.*
  • Phoenix Contact® connector audio inputs
  • Power-saving – if no audio is present after a few minutes, unit automatically disables power to IR diodes, reducing power consumption by 80 percent.
  • WIR TX75 S slave emitter available (sold separately)
  • Headset, stethoset and body-pack receivers available for use with WIR TX75 C or WIR TX75 D PRO (sold separately).
  • Robust digital communication bus between master and slave units reduces interference.
  • Master unit has troubleshooting lights built in to simplify installation.
  • Separate phoenix audio inputs for each channel - 2.3/2.8 MHz accept balanced or unbalanced line level inputs; use together for stereo operation or separately for mono.
  • Unit senses if only one channel is in use and doubles the output power on that channel for twice the coverage.
  • 5-year warranty

*Operating range varies based on receiver used.  See emitter specifications for coverage area by receiver type.


WIR TX75 C Architectural and Engineering Specifications

  • The infrared transmitter shall consist of an all in one modulator and emitter operating on 2.3/2.8 MHz or 3.3/3.8MHz. The carrier frequency shall use 50kHz deviation and 50µS pre-emphasis.
  • The transmitter shall have a minimum coverage of 12,000 sq ft with the WIR RX22-4 receiver in single-channel mode.
  • The transmitter shall be housed in a heavy-duty black plastic enclosure with a durable infra-red transparent front lens. It shall be convection cooled without fans. The transmitter includes an omni-directional mounting bracket for various permanent installations.
  • The transmitter shall have a line level phoenix jack input for each of the channels. Each channel shall have an audio input level LED. There shall be a single 3.5mm microphone input with gain control. The mic input shall have a channel selector switch.
  • The transmitter shall have a switch to turn off all indicator LED’s.
  • The transmitter shall have two RJ45 outputs supplying power and baseband signal to two WIR TX75-S slave emitters via CAT-5e cable. Each RJ45 output shall have a green and yellow LED signaling that the slave emitters are receiving power and baseband signal. A single CAT-5e cable supplies power, signal and digital control to the slave unit up to 100 ft from the transmitter.
  • The transmitter shall be powered by a 48VDC universal power supply, 50-60Hz, 100-240 VAC input, 19.2W.
  • The transmiiter shall be covered by a two-year parts and labor warranty, 90 days on accessories.
  • The transmitter operating on 2.3/2.8 MHz shall be the Williams Sound model WIR TX75 C.
  • The transmitter operating on 3.3/3.8 MHz shall be the Williams Sound model WIR TX75 D.


Dimensions, Weight:

10.0" W (25.4 cm) x 3.1" D (7.9 cm) x 1.5" H (3.8 cm) w/o faceplate or 2.5" H (6.4 cm) w/faceplate, 0.6 lbs (0.3kg)


Black with silver colored silk screen and silver colored faceplate

Optional: white colored faceplate

Power Supply:

Desktop style international power supply with IEC line cord, 100-240 VAC input, 50-60Hz, 24W; 48VDC output

DC Power Input:

2.5mm ID barrel connector, 48 VDC, 0.4A center positive

Power Indicator:

Green LED

Sleep/Power Save Mode:

Shuts off carrier when no audio is present for 3 minutes


FM Wideband, ±50kHz deviation max, 50 μS pre-emphasis

Carrier Frequencies:

WIR TX75 C: 2.3 MHz (Ch1) and 2.8 MHz (Ch2)

WIR TX75 D: 3.3 MHz (Ch1) and 3.8 MHz (Ch2)

Default at power on = carriers off. Carriers are automatically enabled upon presence of audio.

Emitter IR Power:

0.7 W

Master Only Coverage Area
(minimum, 1-Ch mode):

12,000 sq. ft. (464 sq. m.) in single-channel mode with the RX22-4 receiver

6,000 sq. ft. (557 sq. m.) in single-channel mode with the RX15-2 receiver

4,000 sq. ft. (186 sq. m.) in single-channel mode with the RX18 receiver

Audio Inputs / Controls:

Line inputs: Phoenix Contact® connectors for Ch1 and Ch2 accept line level, balanced or unbalanced audio

Microphone input:

3.5 mm, stereo jack with signal and bias connected to tip, electret microphone compatible (4 VDC bias supply with 2.7k ohm series resistor)

Microphone gain adjust:

Rotary potentiometer

Microphone channel switch:

Selects microphone input to Ch1 or Ch2

Audio indicators:

Yellow LED blinks at nominal audio level. One per channel

Indicators On/Off:

2-position switch turns on/off indicator lights

“to slave" Output/Input:

(2) 8p8c RJ45 connectors output 48VDC 0.4A power, baseband RF and a bi-directional RS-485 bus for control and status communications

Slave Status Indicators
(on “to slave" jacks):

Green: Power/Unit Status

Yellow: Transmit/Cable Status

Signal-to-Noise Ratio:

70 dB, (line input)

Frequency Response:

95Hz to 17.6kHz, -3dB re 1kHz (line inputs)

125Hz to 17.0KHz, -3dB re 1kHz (microphone input)

Total Harmonic Distortion:

<1% (1 kHz, nominal deviation, line or microphone input)

Operating Requirements:

0-50° C (32°-122°F)

Mounting Kit:

Wall or Ceiling mount: BKT 024 Omnidirectional mount

Optional: slave linking bar (MLB 003)


5 Years


CE, C-tick, FCC, Industry Canada, WEEE, RoHS, CB Scheme

Compatible Receivers:

WIR RX22-4, WIR RX18, WIR RX15-2

Other Models


Accessories for Infrared Transmitter 2.3/2.8 MHz [WIR TX75 C]

BKT 024 Wall/ceiling mounting bracket

MLB 003 Linking Bar for WIR TX75

TFP 046 Power supply for WIR TX75 PRO


Download/View Name Type Language
WIR TX75 C/D Specifications Specifications English
IR for Ease EASE English
Building Information Modeling (BIM) CAD Drawings English
WIR TX75 C/D Quick Setup Guide Manuals English
White Paper - Powering the TX 75 with PoE White Papers English
Infrared Brochure - High Res Brochures English
DC6 - Powering TX75 VIA CAT5.pdf CAD Drawings English
WIR TX75 C/D Manual Manuals English


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