Olson Technology OTR-3550-DC - Manual (Page 3)

025-000187 REV B Page 3
B) BAND SELECTION - Band selection is accomplished by setting the 6-position DIP switch to select
the correct band for the desired channel. The second, third and fourth switch positions of the 6-
position DIP switch are used for band selection. Switch settings for the band select switch are included
with the channel codes in Table 4 at the rear of this manual.
For example, the correct band switch setting for channel DS-1 is:
C) AFC SELECTION - The OTR-3550-DC has an AFC circuit which may be switched-on if
the channel being received has a tendency to drift around in frequency. Although this feature may not
normally be needed, it may be activated by moving position 5 of the 6-position DIP switch down.
The AFC is shown as selected off in Table 4.
For example, the correct setting for channel SD-22 with the AFC on would be:
D) INPUT CONNECTION - After the input selection DIP switches have been properly set (Steps A
through C), connect an antenna or cable source to the RF Input fitting. Any VHF, UHF or cable
source can be connected to the RF input. For optimum video quality, the input signal level should be
+10dBmV. This unit has an internal squelch circuit that will cut off signals below -30dBmV.
3) DEMODULATOR AGC ADJUSTMENT
The demodulator delayed AGC adjustment is factory set for a +5 to +10dBmV threshold. This setting provides
the best signal-to-noise ratio for low level off-air signals.
When operating the OTR-3550-DC with cable channels at the input, where high-level adjacent channel signals
may be present, adjacent channel performance may be improved by lowering the AGC threshold level.
To adjust the delayed AGC threshold level for cable signal inputs:
A. Connect a cable source carrying three adjacent channels at a level of +20dBmV maximum to
the RF input connector. Connect a television receiver, through approximately 50dB of attenuation
so as not to overload it, to the OTR-3550-DC output.
B. Set the input channel select DIP switches to the channel located in the center of the three
channels. Set the television receiver to the output channel of the OTR-3550-DC.
C. Remove the OTR-3550-DC top cover and locate the delayed AGC control potentiometer
R54. R54 is located near the center of the circuit board towards the front of the unit. Adjust
the demodulator delayed AGC control (R54) slightly for the least amount of adjacent channel
interference as seen on the television receiver.