Sennheiser EM500 - Manual (Page 49)

Synchronizing transmitters with receivers
48
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On one of the receivers, select a channel within this frequency bank
(see page 39).
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Assign this channel one of the receiving frequencies (see page 39).
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Synchronize a transmitter with the receiver (see page 22).
OR
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Manually set the transmitter to the same frequency bank, channel and
frequency that you set on the receiver.
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Repeat for the remaining transmitters and receivers as described
above.