Checking The Agc Pot Adjustments - RESEARCH CONCEPTS RC2000A DUAL AXIS Instructions Manual

RC2000A Dual Axis Antenna Controller Appendix I
specified at the end of the previous sentence).
If both controller AGC inputs are utilized, record similar values for 'RCV2 – on satellite – strong
band' ______ (C or Ku band) and 'RCV2 – off satellite – weak band' _____ (C or Ku band). If both
controller AGC inputs are utilized steps 7 through 9 must be performed for each AGC channel. Use
the Scroll Up/Down keys to view the AGC channel whose pots are being adjusted.
7. Go to MANUAL mode, position the antenna 'RCVx - off satellite – weak band' (if it is not already
there), 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, 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, turn the GAIN pot
clockwise.
8. While still in MANUAL mode, position the antenna 'RCVx - on satellite – strong band' 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 650.
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, 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, adjust the
OFFSET pot counter-clockwise.
9. Position the antenna 'RCVx - off satellite – weak band'. If the signal strength is between 50 and
100, proceed to step 11. If the signal strength is less than 50 or greater than 100 perform steps 8
and 9 again.
10. Position the antenna 'RCVx - on satellite – strong band'. Jog the antenna off of the satellite until the
picture is just barely watchable. Note the signal strength value. Go to CONFIG mode and use the
SCROLL keys to bring up either the AGC C Band Threshold item or the AGC K Band Threshold
item, whichever is appropriate for the frequency band that the user has chosen to operate at (and
has adjusted the pots at). Key in the signal strength value noted above. Terminate the entry with
the ENTER key.
For a dual receiver system, both AGC channels are used. The thing to remember is that the same
'Threshold value is applied to both channels for operation at a given band.

1.2 Checking the AGC Pot Adjustments

In the previous section a procedure was presented to adjust the AGC pots and to determine the AGC
C/Ku Band Thresholds. That adjustment was performed using one transponder on one strong satellite.
After the AGC pot adjustment has been performed a check should be made to insure that the
adjustments are valid for all transponders on strong and weak satellites. In some cases, additional
potentiometer or 'Threshold adjustments may be required.
To understand the tests that need to be performed, recall that the purpose of the AGC input is to let the
controller determine whether a satellite signal is present or not, and to provide relative signal strength
information when for peaking the antenna. A signal is assumed to be present whenever the AGC input
is above the threshold level for whichever band - C or Ku - has been selected.
Three possible problems can be encountered ...
i) The receiver is tuned to an inactive transponder and the AGC input is above the appropriate
Threshold. In this case the controller will attempt to peak the antenna because the AGC input is above
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Signal Strength Peakup
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