American Fibertek MR-05B - Manual (Page 3)

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This unit requires a 24 VAC power source with an isolated output for proper operation. Current draw is
approximately 2.5 VA maximum. In the USA and in Canada an American Fibertek PS-24 is supplied
with this unit. ANSI/NFPA 70 Class 2 wiring is recommended.
POWER CONNECTION
Power is supplied to the unit via a two pin terminal connector. See the drawing at the bottom of this
page for proper location of the 24 volt ac input.
FIBER CONNECTION
The fiber optic connection is made via a ST connector located on the side of the unit.
AUDIO OUTPUT LEVELS
The audio output signal appears on both the plus and minus terminals of this unit. Half of the signal
appears on each output terminal. The two outputs are 180° out of phase. In a balanced audio
configuration, the output connection is made across both the plus and the minus terminals. The
balanced output impedance is 600 Ohms. To connect unbalanced, the plus output is used for the audio
connection, along with the ground terminal. The output signal level will be half of the input level (-6dB)
in this configuration. The unbalanced output impedance is 300 Ohms.
BALANCED AUDIO OUTPUT CONNECTIONS
The audio output connections are made via a three pin terminal connector on the side of the unit. A
balanced audio product is connected directly to the plus and minus terminals. The shield or earth wire
is connected to the ground terminal. See the drawing below for proper orientation of the audio output
wires. For optimum performance the audio wires should be the shortest length practical.
UNBALANCED AUDIO OUTPUT CONNECTIONS
The audio output connections are made via a three pin terminal connector on the side of the unit. To
obtain an unbalanced output signal, only the audio out plus terminal and the ground terminal are used.
The audio out minus terminal is not connected. When used in the unbalanced configuration, there will
be a loss of –6dB relative to the audio signal input at the corresponding fiber transmitter. See the
drawing on the next page for proper orientation of the audio output wires. For optimum performance the
audio wires should be the shortest length practical.