Olson Technology OTR-3550-SW - Manual (Page 10)

025-000232 REV C Page 10
5) VIDEO MODULATION ADJUSTMENT
A) Connect a video source of approximately 1V p-p to the video input connector (75 ohms input Z) on the
rear panel. The video should be of a reasonably bright scene (commercials are usually excellent).
B) Rotate the video modulation level adjust control slowly clockwise until the video overmodulation LED 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.
6) AUDIO MODULATION ADJUSTMENT
A) Connect an audio source of 300mV p-p (minimum) to the balanced audio input connector (600 ohms
input Z) on the rear panel. The source should be typical of the program material to be carried.
B) Rotate the audio modulation level adjust control slowly clockwise until the audio overmodulation LED just
begins to blink. CAUTION: Overmodulation can result in severe distortion in some TV sets. Set this
control at peak program levels.
7) RF AND AURAL CARRIER LEVEL ADJUSTMENT
A) Using a field strength meter, set the video carrier to the desired level with the RF output level adjust control.
B) Tune the field strength meter to the aural carrier (4.5MHz above the video carrier).
C) Adjust the aural carrier level control 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 spuri-
ous signals in adjacent channels.
8) MISCELLANEOUS
A) The OTR-3550-SW is BTSC stereo compatible. It is shipped in the “mono” mode. To defeat
pre-emphasis, in order to use a composite BTSC baseband input signal, move the internal jumper plug
from W-9 to W-10. This plug is located in the left front area of the circuit board.
B) If a scrambling unit is utilized with the OTR-3550-SW, follow the instructions associated with the
scrambler. The video I.F. output level is +40dBmV, and the audio carrier level is determined by the aural
carrier level adjustment - typically +17dBmV @ 15dB A/V ratio.
C) This unit 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.
D) A -20dB test point (type F connector) is provided in the rear panel.