Research Concepts RC2000C - Manual (Page 39)

RC2000C Az/El Tracking Antenna Controller Chapter 4 Inclined Orbit Satellites 31
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Note that the GAIN and OFFSET adjustments are implemented using 20 turn pots. A lot of turns
may be required.
If the receiver has POSITIVE polarity proceed to step 7. If the receiver has NEGATIVE polarity
proceed to step 8.
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 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 (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.
10. Position the antenna 'on satellite'. 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/L 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.
Typical CONFIG mode threshold values are 150 to 300.
Single Receiver - Dual Frequency Band Inclined Orbit Satellite AGC Setup
The setup procedure described above was for the case where a single satellite receiver is connected to
the controller, and the user is interested in tracking only satellites of a single frequency band (either C or
Ku). A slight increase in complexity occurs if the user must be able to track both C and Ku band
inclined orbit satellites. This is because the same AGC channel is used for both frequency bands, and
therefore the OFFSET and GAIN pot adjustments for that channel must be made so as to
accommodate both frequency bands. At the heart of the problem is the fact that the signal strength (as
seen by the receiver's AGC circuits) will vary with the frequency band selected due to differences in
antenna gain, LNB gain, and the differences in output power between C, Ku, and L band satellites.
The adjustment procedure for the dual band case is very similar to the single band case described
above. The following paragraphs describe the modifications required to adapt the single receiver -
single band procedure, to the single receiver - dual band case.
1. The procedure is similar to step 1 above except that the user should align the antenna with a strong
C band and a strong Ku (or L) band satellite. The voltages for each frequency band should be
recorded.
2. Similar to step 2 above except that both C and Ku (or L) band AGC voltages are obtained when the
antenna is looking at nothing.