Portable Display FM Transmitter (150 MHz)
LT-700-150

Highlights

  • Portable transmission – Broadcast the interpreter or tour guide’s voice to everyone in the audience without having to carry a microphone or be plugged into a wall.
  • Superior Audio Quality – 80 dB signal-to-noise ratio, setting the industry’s sound quality standard.
  • With a choice between 32 channels, Listen products are ideal for a wide range of applications.
  • 100 % Digital – Listen receivers are digitally-tuned so transmission won’t drift; assurance that when a channel is selected, it stays on that channel.
  • Uses standard alkaline or NiMH batteries – Built in SmartCharge™ won’t allow batteries to overcharge (NiMH batteries only).
  • Look & Listen™ LCD shows channel, battery status, and programming information.
  • Up to six (6) simultaneous transmitted channels.
  • Transformer charging plug or drop in charging contacts.
  • Built in SmartCharge™ won’t allow batteries to overcharge. Charging circuitry is conveniently built into Listen’s LT-700-150 Transmitter; never worry about unplugging a transformer at a certain time.
  • Mute switch.
  • Mic and/or line level inputs.
  • Many accessory options make Listen products ideal for a wide range of applications.
  • Limited Lifetime Warranty with hassle-free support.

Overview

The Listen LT-700 Portable Transmitter is used to wirelessly broadcast audio for a variety of portable applications. Whether its voice or music, the user can broadcast audio to everyone in the audience without having to carry a microphone or be plugged into a wall. The LT-700 is excellent for factory tours, outdoor events, wireless microphone applications, classrooms, training, or personal use – anywhere amplified sound is needed, with no installed system is present. With the many features of the LT-700, portable transmission has never been easier for users!

Note: for use in Australia

Includes

LT-700-150 Portable Display FM Receiver (150 MHz)
Quick Reference Card

Architectural Specs

The portable FM transmitter shall be capable of broadcasting on 32 channels. The unit shall incorporate a microphone sensitivity switch. The device shall broadcast on both wide and narrow band channels with a SNR of 80 dB or greater. The device shall have an audio frequency response of 50 Hz to 15 KHz (±3 dB). The device will incorporate a mute switch. The battery door shall be capable of being mechanically locked. The device shall incorporate an LCD display that indicates channel, battery level, low battery, battery charging, and RF signal strength. The device shall be able to enable companding. The unit shall operate off of two (2) AA batteries; alkaline or NiMH. The portable transmitter shall incorporate automatic battery charging circuitry for recharging of NiMH batteries, with the ability to charge via a wall transformer or drop in charging case. The Listen LT-700-150 is specified.

Specifications

 SpecificationsLT-700-150
AudioRF Frequency Range150.8000 MHz - 152.3500 MHz     
Number of Channels6 wideband, 26 narrowband
Number of Simultaneous TransmittersSix (6)
Frequency Accuracy± .005% stability 32 to 122º (0 to 50ºC)
Transmitter Stability50 PPM
Transmission Rangeup to 45.7m (150 ft.)
Output Power10 mW maximum
AntennaUses microphone cable
Antenna Connector3.5 mm connector
ComplianceC-Tick
System Frequency Response50 Hz - 15 kHz (±3dB)
System Signal to Noise RatioSQ enabled 80 dB, SQ disabled 60 dB
System Distortion<2% total harmonic distortion (THD) at 80% deviation
Microphone InputUnbalanced, tip of 3.5mm connector, -20 dbu nominal,
-30 dbu maximum, impedance 21 ohms
Microphone SensitivityThree position switch: high, middle, and low; 6db increments
Line InputUnbalanced, ring of 3.5mm connector, -10 dbu nominal input level,
-3 dbu maximum, impedance 10K ohms
Microphone Power3VDC Bias
 
Controls & IndicatorsUser ControlsPower, mute, channel UP/DOWN
Set-up Controls (battery compartment)Mic sensitivity, NiMH/alkaline battery, SQ enable/disable
ProgrammingChannel lock out, Channel lock
LEDRed, illuminated when unit is on. Flashes when batteries are low,
or to indicate charging. Flashes when muted.
DisplayChannel Designation, lock status, signal strength indication, battery life, RF Power
   
 Battery TypeTwo (2) AA batteries, alkaline or NiMH
PowerBattery Life (Listen batteries)15 hours alkaline (LA-361), 8 hours NiMH rechargeable (LA-362)
Battery Charging (NIMH only)Fully automatic, 13 hours
Power Supply I/P 120VAC; O/P 7.5VDC 250 mA; Drop in contact points for use with charging cases. Power supply not included (LA-202)
Power Supply Connector2.3mm OD by 0.7mm ID, barrel type connector 7.5 VDC, center positive <250mA. Drop in contact points for use with Listen charging cases
Power Supply ComplianceRoHS, WEEE, UL, PSE, CE, CUL, TUV, CB compliant
   
PhysicalDimensions (H x W x D)3.00 x 1.00 x 5.00 in. (7.6 x 2.5 x 13.0 cm)
ColorDark Grey with white silk screening
Unit Weight3.9 oz (111g)
Unit Weight with batteries5.8 oz (164g)
Shipping Weight1.0 lbs. (0.45kg)
DoorManually Lockable (on sides). Up, down, and power buttons through door
   
EnvironmentalTemperature - Operation14 to 104º F (-10 to 40º C) 
Temperature - Storage-4 to 122° F (-20 to 50° C)
Humidity0 to 95% relative humidity, non-condensing
   
Specifications are subject to change without notification

Requirements

Used With

Accessories

Support Documents

    • FAQ

    What is the range of the LT-700-150 portable transmitter?
    Line of site up to 45.7 m (150 ft.).
     
    Can I have multiple transmitters operating in one facility?
    Yes. There can be up six (6) simultaneous channels with 150 MHz.
     
    Can I use a line source with the portable transmitter?
    Yes. Listen offers the LA-263, a mic/line input cable for this use.
     
    How long do the batteries last on the portable transmitter?
    Alkaline batteries last 15hours; NiMH rechargeable batteries last 8 hours.
    Does the LT-700-150 provide phantom power?
    Yes, 3VDC for electret condenser microphones.
     
    Will the LT-700-150 portable transmitter work for two-way communication?
    No. However, Listen does not recommend a two-way system for tour group applications. A two-way system means that everyone hears every sniffle, cough, comment etc. The tour guide loses control of the tour and the tour becomes unproductive.

    Troubleshooting Guide

    What is the range of this transmitter?

    • A range of up to 150 feet is achievable depending upon the following:

      • The orientation of the Microphone cord, which is the transmitting antenna.
      • The objects between the transmitter and receiver. All material, especially metal, will weaken the signal strength.
      • The type of receiver and its receiving antenna.

    What channels should I be transmitting on?

    • It is recommended that wideband channels are used for best audio quality. If transmitting multiple simultaneous channels, narrowband frequencies may be required.

    The signal being transmitted is inconsistent, my receivers cut in and out.

    • The receivers may be out of range of the transmitter.

    How do I connect my TV, VCR, CD player, etc. to this transmitter?

    • Listen provides a Line Input Cable (LA-263) that will allow you to connect an RCA connection to the transmitter.

    My microphone sounds very low in audio level.

    • Make sure that the microphone sensitivity switch, located in the battery compartment, is in the correct position. Consult the microphone users manual for the correct setting.

    What type of microphones can I use with this transmitter?

    • Any Listen condenser microphone may be used with this transmitter.

    My batteries will not charge.

    • Make sure you are using NiMH batteries.
    • Make sure the battery select switch, located in the battery compartment, is in the NiMH position.
    • Make sure that the power cord is plugged in properly.
    • If using a charging case, make sure that the transmitter is properly placed in the charging pocket.

    The batteries in my transmitter will not hold a charge.

    • It is time to replace the batteries. Listen recommends that the batteries be replaced every 3 years or after 500 charges.
    • Make sure that the transmitter is actually receiving the charge. The red LED on top of the transmitter will flash when charging.
    • Make sure that the unit is being turned off when not in use.

    When I use the mute function, the auxiliary input can still be heard.

    • The Mute function only mutes the microphone input. Any auxiliary audio input will still be transmitted.

    How do I lock out channels?

    • Enter the program mode by holding the UP and DOWN buttons simultaneously for 5 seconds. The PGM icon will appear. Once in the program mode, scroll through the channels using the UP and Down buttons. Briefly pressing the power button will toggle each channel in and out of Lockout. When the channel is locked out, the L/O will be displayed on the LCD indicating that channel is locked out.

       

     

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