Channel Selection

It is important to choose channels that are free from interference to achieve proper operation of your Listen equipment. This process is trial and error. Before turning on the transmitter, listen to the wide band channels on the receivers (lettered channels at 72 MHz and channels that start with a “2” for 216 MHz when using a Listen receiver). Listen to the audio through the headphone or via the speaker and choose a channel with the least amount of interference. Unless you are interfacing with an existing narrowband transmission system, always use a wide band channel.

If you are using multiple channels follow this process:

1.Same Space If you are using multiple transmitters in the same space, the highest number of channels that will work simultaneously is six at

72 MHz and three at 216 MHz. With all of the transmitters

off, listen for interference on all the wide band channels with a

Listen receiver. Using the frequency compatibility tables on pages 15-17, eliminate any channels that have noticeable interference. Now choose the channels with the widest channel spacing. It is recommended that adjacent channels be spaced at least 300k Hz apart. If there is no interference the following channels are recommended. For a 72 MHz system, use channels A, C, E, I, J and H. For a 216 MHz system, use channels 2A, 2K and 2V.

2.Distributed Spacing If you are using transmitters that are distributed over a large area, you can achieve more simultaneous broadcast channels. However, it is critical that your receiver(s) be located as close to its transmitter as possible. You can use adjacent channels (see frequency compatibility tables (on pages 15-17) in this case as long as the adjacent channel transmitter is at least 50% further away from the receiver than the original transmitter. Example: The transmitter for the receiver on channel E is 100 feet from the receiver. The adjacent channel transmitter on channel D should be at least 150 feet away.

It is highly recommended that after channel selection has been achieved, you lock the channel so that it cannot be changed by the user. To accomplish LOCK on the LT-800, press the “UP” button for 3 seconds. Repeat the process to unlock.

Notes in regard to using 72 MHz and 216 MHz systems:

1.72 MHz is a secondary frequency band. This means that other transmitters are licensed to use these frequencies. Thus, you may experience interference from paging transmitters and other types of transmissions. You will need to find a clear channel by listening to all the wide band channels.

2.216 MHz is a primary frequency band and no other types of transmissions are authorized to use it. Thus, you will find the highest probability of clear channels in this band. However, you may experience intermodulation of the TV Channel 13 aural carrier if there is a channel 13 transmitter in your area and you are close to the transmitter. If you cannot find a clear channel in 216 MHz band due to channel 13, it is recommended that you switch to

a 72 MHz system.

Wide Band Recommendation Listen recommends that you always use a wide band channel unless you need to be compatible with existing narrow band receivers from other manufacturers. Wide band channels have lower noise than their narrow band counterparts.

At 72MHz

The LT-800 at 72 MHz operates on 17 wide band channels and 40 narrow band channels.

•Letters= Wide Band Channels

(Example: E)

•Numbers= Narrow Band Channels

(Example: 32)

At 216MHz

The LT-800 at 216 MHz operates on 19 wide band channels and 38 nar- row band channels.

•“2” as left digit= Wide Band

Channel (Example: 2C)

•“1” and “3” as left digits= Narrow

Band Channels (Examples: 1A; 3R)

LT-800-072, LT-800-216 specifications

Listen Technologies has established itself as a leading provider of assistive listening systems, and its LT-800-072 and LT-800-216 transmitters are exemplars of their commitment to quality and innovation. These devices are designed to enhance the audio experience in environments where clear sound transmission is crucial, such as theaters, lecture halls, museums, and places of worship.

The LT-800-072 is a powerful, reliable FM transmitter that operates on the 72-76 MHz frequency band. It supports both mono and stereo transmission, making it versatile for various applications. One of its standout features is its robust selectable power output, which allows users to adjust the strength of the transmission based on the specific requirements of the environment, ensuring optimal coverage without interference. This flexibility is particularly beneficial in larger spaces, where sound needs to travel further without losing clarity.

On the other hand, the LT-800-216 is designed for use within the 216 MHz frequency range, offering another layer of versatility for varying listening preferences and regulatory requirements. It boasts a compact design, making it easy to integrate into existing audio systems or set up independently. The device also features a built-in audio input that accommodates multiple audio sources, including microphones, mixers, and other devices, allowing for seamless integration and functionality.

Both transmitters utilize advanced technology to deliver exceptional audio quality. The modulation techniques employed in these devices help eliminate static and background noise, ensuring that users receive crystal clear sound. The inclusion of multiple channels allows simultaneous transmission, which is a significant advantage in settings where multiple languages or presentation options are necessary.

Durability and ease of use are also critical characteristics of the LT-800-072 and LT-800-216. They are constructed with high-quality materials that withstand the rigors of regular use, making them ideal for both permanent installations and portable applications. Additionally, user-friendly controls and clear indicators simplify operation, enabling operators to focus on delivering an excellent auditory experience rather than troubleshooting technical issues.

In summary, the Listen Technologies LT-800-072 and LT-800-216 transmitters provide advanced sound transmission solutions characterized by flexibility, excellent sound quality, and robust build quality. Their capabilities make them suitable for various applications, effectively addressing the diverse needs of listeners in a range of environments.

Listen Technologies LT-800-216, LT-800-072 manual Channel Selection

Models: LT-800-072 LT-800-216