Larcan FM-250, Technical Manual

Page: 29 / 86

FM-250 FM BROADCASTING EXCITER
Issue Date: 21 Jan 2003
INSTALLATION
STAND ALONE CONFIGURATION (Stereo Exciter)
The following information sets out the general requirements for installation and operation of the
above equipment in a "stand alone" configuration.
Note: The Audio program inputs (Left and Right), may vary in level from the standard factory
sensitivity setting, and adjustment may have to be made internally (due to the Stereo coders
built in Limiter). The Limiter threshold level is factory set to limit the deviation of the audio
signal to
±
62.5kHz. (Adjustable)
The pilot deviation is factory set to
±
7kHz. The total deviation must not exceed
±
75kHz. A fine
deviation level adjustment of 0 to -3dB is available on the front panel to allow for small
variations.
The operating frequency will normally be set at factory configuration, but if a different operating
frequency is necessary then the unit top cover has to be removed and a new frequency
selected on the Synthesizer module (980507). This is simply done by setting the direct
readout on the rotary BCD switches.
1.
ELECTRICAL CONNECTIONS
Ensure that the power on/off switch on the front panel is switched off before proceeding.
a) A/C MAINS SUPPLY (110V 60Hz).
Connect a/c power cable to IEC connector on back panel.
b) DC SUPPLY (+48V dc).
Connect dc power input to the dc supply terminals on the back panel observing correct
polarity.
c) RF OUTPUT.
Connect the Antenna cable to the RF Output on the back panel using an N type connector
or via suitable adapters.
d) AUDIO INPUTS.
Connect the Left and Right audio feeds (XLR male) to the Left and Right (XLR male)
inputs on the back panel.
e) PRE EMPHASIS.
Set the pre emphasis switch to "ON" at the back panel.
Note: When the Telemetry connector is not in use the unit requires no external commands to
enable the RF. The unit is also ready for Stereo operation. These functions can be changed via
link commands on the Telemetry connector. See "9" Telemetry connections (PL7).