Research Concepts RC1500 - Manual (Page 24)

AGC Tuning
RC1500B Quick Start Guide 24
mode and examine the signal strength for the AGC channel which was not
selected in step 3 above. If the signal strength reading for that channel is
greater than 10, adjust the OFFSET and GAIN pots for that channel until the
signal strength reading for that channel is less than 10. To lower the
displayed signal strength value, turn the OFFSET pot counter-clockwise and
the SCALE pot clockwise. When this is accomplished proceed to step 6.
6. In the next few steps of the procedure, the OFFSET and GAIN pots of the
AGC channel connected to the receiver’s AGC output are adjusted so that the
‘off satellite’ signal strength value is between 50 and 100 and the ‘on satellite’
signal strength value is between about 950..
Note that the GAIN and OFFSET adjustments are implemented using 20 turn
pots. A lot of turns may be required.
7. Go to MANUAL mode, position the antenna ‘off satellite’, and adjust the
OFFSET pot (for POSITIVE polarity receivers) or the GAIN pot (for
NEGATIVE polarity receivers) so that the signal strength reading is about 75.
If the AGC has POSITIVE polarity and the signal strength is too low, turn the
OFFSET pot counter-clockwise. If the AGC has POSITIVE polarity and the
signal strength is too high (or is ‘***’), turn the OFFSET pot clockwise.
If the AGC has NEGATIVE polarity and the signal strength is too low, turn the
GAIN pot counter-clockwise. If the AGC has NEGATIVE polarity and the
signal strength is too high (or is ‘***’), turn the GAIN pot clockwise.
8. While still in MANUAL mode, position the antenna ‘on satellite’ and adjust the
GAIN pot (for POSITIVE polarity receivers) or the OFFSET pot (for
NEGATIVE polarity receivers) so that the signal strength value is about 950.
If the AGC has POSITIVE polarity and the signal strength is too low, adjust
the GAIN pot clockwise. If the AGC has POSITIVE polarity and the signal
strength value is too high (or is ‘***’), adjust the GAIN pot counter-clockwise.
If the AGC has NEGATIVE polarity and the signal strength is too low, adjust
the OFFSET pot clockwise. If the AGC has NEGATIVE polarity and the
signal strength value is too high (or is ‘***’), adjust the OFFSET pot counter-
clockwise.
9. Position the antenna ‘off satellite’. If the signal strength is between 50 and
100, proceed to step 10. If the signal strength is less than 50 or greater than
100 perform steps 7 and 8 again.