BW Broadcast technical manual
Page 23
Installation and setup
ADVANCED SETUP PROCEDURE
The front panel LCD metering is accurate enough to set up the transmitter in the absence of external test equip-
ment. If you have access to a modulation meter and RF power meter then substitute those for references to the
relevant LCD display menu.
You will most likely need the following pieces of test equipment:
Audio signal generator capable of -10dbu to +10dbu
Voltmeter
2.52 Multiplex input only.
Open the lid of the transmitter and make sure that jumper J1 on the main board is configured so that MPX
Loopthrough is OFF. This makes sure that the internal stereo encoder is not connected through to the modula-
tor. Connect your wideband audio source (processor, coder or rebroadcast receiver) to the multiplex input on the
back panel. Setup your external equipment for its correct output level making sure that it falls into the range of -6
to +10 dbu. Adjust the multiplex input level control on the back panel for a peak deviation of +/- 75kHz. The peak
deviation can be shown on the LCD system.
The factory setting for the multiplex input level is +6dBu. This corresponds to the output level of our internal ster-
eo encoder module. We recommend feeding this level input to the multiplex input socket if it is available from the
external equipment.
2.53 Stereo with internal limiters.
The transmitter will come set to this mode from factory with the following settings. Input Gain at maximum, limiter
active and in loud mode, limiter clippers on and 15 kHz filter clippers on. This provides the loudest, most competi-
tive settings available with the transmitter without using an external multiband processor to significantly boost
loudness.
The gain controls on the back panel control the input drive to the limiter module and can be set so that limiting
occurs for a given input level. Factory setting is at maximum to enable maximum compression / limiting so that a
loud commercial sound is obtained. You can reduce your input level to suit the amount of compression required.
The Limiter ON jumper is set so that the limiter is enabled. The limiter clippers are on to define the maximum out-
put from the limiter under any conditions. The Limiter has two modes of limiting, Loud and Clarity. Loud will give a
more processed brighter sound and Clarity will retain a sound more true to the original audio input. If you want a
more punchy commercial sound leave the limiter in Loud mode. The 15 kHz filters have overshoot clippers after
them. These if activated remove any overshoots caused by ringing in the filters. These are best left active if you
want the loudest sound for a peak deviation of +/- 75 kHz. (See note on 15 kHz filters at the end of the section)
Advanced setup procedure.
1. Firstly make sure that the exciter is set to your chosen operating frequency. If you have not already done so
then remove the top cover from the transmitter.
2. Connect the transmitter to a dummy load.
3. Turn on the transmitter and within 15 seconds it should lock to frequency.
4. Set the internal limiter to OFF with jumper J8. Set the limiter clippers to ON with jumpers J6 and J7. Set the 15
kHz filter clipper jumpers J9 and J10 to ON. Remove the pre-emphasis jumpers from J2 and J3 completely for
now. Make sure the loopthrough jumper J1 is switched to LOOPTHROUGH and the MONO FROM LEFT jumper
J12 is set to the OFF position. Disable the stereo pilot by setting jumper J11 to MONO. Set the limiter mode jump-
er J4 and J5 to LOUD.
These settings will allow any audio straight through the limiter and into the limiter clippers that set our final peak
level.
5. We should check that any offsets internal to the limiter are nulled out to keep distortion to a minimum. Connect
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