Dual Frequency Band Potentiometer Adjustment - RESEARCH CONCEPTS RC2000A DUAL AXIS Instructions Manual

RC2000A Dual Axis Antenna Controller Appendix I
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 '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, 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 'off satellite'. 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 '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 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. There are unique
'Threshold values for each band.

1.1.2 Dual Frequency Band Potentiometer Adjustment

The setup procedure described above was for a single band antenna system (either C or Ku). A slight
increase in complexity occurs dual C and Ku band operation. 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
and Ku band satellites.
1. Align the antenna with a strong C band satellite. Place a voltmeter on the receiver's AGC output,
measure and record the voltage. This voltage will be referred to as 'RCV1 - on satellite – C band'
where 'n' is 1 or 2 depending on which AGC channel is used. In a similar manner, align the
antenna with a strong Ku band satellite. Record the receiver voltage. This voltage will be referred
to as 'RCV1 – on satellite – Ku band'.
Note that if both AGC inputs will be utilized, record the 'on satellite' voltages associated with the
other receiver 'RCV2 – on satellite – C band' and 'RCV2 – on satellite – Ku band'.
2. Jog the antenna away from any satellites so the antenna is looking at nothing. Measure and record
the receiver's AGC voltage. Refer to these voltages as 'RCV1 – off satellite – C band', 'RCV1 – off
satellite – Ku band'.
Note that if both AGC inputs will be utilized, also record the 'off satellite' voltages for the other
receiver ... 'RCV2 – off satellite – C band' and 'RCV2 – off satellite – Ku band'.
3. Choose that band that has the greatest difference between the 'on satellite' and 'off satellite'
voltages. If the difference between the two is less than 1 volt, connect the receiver's AGC output to
the controller's AGC1 input. Otherwise, connect the receiver's AGC output to the controller's AGC2
input. Be sure to connect the ground return of the controller to a ground on the receiver. See figure
3.1.
Note that if both AGC channels will be utilized, connect the Signal Strength output of the receiver
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Signal Strength Peakup
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