Channel Selection - Listen Technologies LR-300 User Manual

Channel Selection

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 receivers, press and hold seek
for 5 seconds. Repeat the process to unlock. 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 (lettered channels at 72
MHz and channels that start with a "2" for 216 MHz). Listen to the audio through the headphone
or via the speaker. Choose a channel with the least amount of interface. 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:
a. Same Space If you are using transmitters in the same space, the most 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 via the headphone jack. Using the
frequency compatibility tables on pages 77-80, 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 300 KHz. If there is no interference the following
channels are recommended: A, C, E, I, J, and H for 72 MHz and channels 2A, 2K and 2V
at 216 MHz.
b. Distributed Spacing If you are using transmitters that are spread out over space, 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 77-80) in this case as long as the adjacent channel transmitter
is at least 50% further away from the receiver as its 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.
7