Olson Technology DSK-300-S - Manual (Page 5)

025-000377 REV E 5 of 9
6.) AUDIO MODULATION ADJUSTMENT (Each modulator).
Connect the audio source (to be used at approximately 500mV P-P) to the audio input phono jack.
Monitor the audio on a television receiver and adjust the audio modulation control for proper loudness as
compared with some channel known to be modulating at the correct level (such as a broadcast station).
The two sources of audio should be very similar in their content and should be near maximum loudness as
compared to the average level of their program. In other words, compare a loud passage with a loud
passage and set the audio modulation control with this program material. Use caution and do not set this
control too high.
7.) OPERATION WITH COMPOSITE BASEBAND BTSC AUDIO INPUT
The DSK-300-S modulators are compatible with a composite baseband BTSC audio input. An internal
jumper must be changed to remove audio pre-emphasis as required for this application.
To remove audio pre-emphasis, remove cover screws (top, sides, and front), disconnect and remove the
DSK-300-S module from the chassis and remove its left side cover. Locate the small trace to the rear of,
and slightly above U16, which runs up and down just to the rear of C116. Note that this trace is connected
to the rear side of C116. Cut this vertical trace.
Replace the module cover, replace the module in the chassis, and set-up the audio deviation per the
instructions for the BTSC generator being used.
8.) RF OUTPUT AND AURAL CARRIER LEVEL ADJUSTMENT (Each modulator)
A) Using a field strength meter or spectrum analyzer, set the video carrier to the desired level with the
output level (RF) control (typically +40 to +45dBmV).
B) Tune the field strength meter to the aural carrier, which is located 4.5MHz above the video carrier.
C) Adjust the aural carrier level control (A\V) to the desired level, typically 15dB below the video
carrier. CAUTION: Reducing the aural \ visual carrier ratio to less than 15dB can result in high out-
of-band spurious signals on adjacent channels.
9.) MISCELLANEOUS
A) The front panel adjustments (RF, OFFSET, etc.) are small, and somewhat delicate. Use CAUTION
and an adjustment tool that is a proper fit when adjusting these controls.
B) The DSK-300-S is BTSC stereo compatible. Each modulator is shipped in the
“mono” mode. To defeat the pre-emphasis in order to use a composite baseband BTSC input signal,
see section 7 of this manual.
C) The DSK-300-S power supply is equipped with an internal 3Amp. 250V GMA fuse. For continued
safety, and to maintain proper performance of the unit, please replace only with an equivalent fuse.