Olson Technology LCM-600 - Manual (Page 6)

025-000082 REV C Page 6
B) Rotate the video modulation control (MOD) slowly clockwise until the video overmodulation light (O/
M) just turns on. The light may blink with differences in average picture level. CAUTION: If the
modulation is set too high, compression or lack of contrast will occur during high intensity scenes.
7) AUDIO MODULATION ADJUSTMENT (For each of the three modulators)
A) Connect an audio source of 300mv p-p (minimum) to the input connector (10K ohms input Z) on the
rear panel.
B) Rotate the audio modulation (MOD) control slowly clockwise until the audio overmodulation light (O/
M) just begins to blink. CAUTION: Overmodulation can result in severe distortion in some TV sets.
Set this control at peak program levels.
8) RF OUTPUT AND AURAL CARRIER LEVEL ADJUSTMENT (For each of the three modulators)
A) Using a field strength meter or spectrum analyzer, set the video carrier to the desired level with the
output level (RF) control,(typically +50 to +53dBmV).
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 visual/aural carrier ratio to less than 15dB can result in high out-of-band
spurious signals in adjacent channels.
9) MISCELLANEOUS
A) The LCM-600 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, move the internal jumper
plug in the desired modulator from W-1 to W-2. This plug is located in the left rear area of the
modulator P.C. board.
B) The LCM-600 is equipped with a 0.5A slo-blo fuse. For continued safety, and to maintain proper
performance of the unit, please replace only with an equivalent fuse.
C) When installing the LCM-600 in an equipment rack, it is best to leave an empty rack space above
and below the unit to allow for optimum air circulation.