RESEARCH CONCEPTS RC2000A DUAL AXIS Instructions Manual page 108

1. Align the antenna with a strong satellite (geostationary or inclined orbit). Place a voltmeter on the
receiver's AGC output, measure and record the voltage. In the description that follows, the term 'on
satellite' will be used to refer to the antenna aligned with a strong satellite.
Note that if both AGC inputs will be utilized, record the 'on satellite' voltage for both receivers.
2. Jog the antenna off of the satellite so the antenna is looking at nothing. Measure and record the
receiver's AGC voltage. In the description that follows, the term 'off satellite' will be used to refer to
this case where the antenna is positioned well off of any satellite, looking at nothing.
Note that if both AGC inputs will be utilized, record the 'off satellite' voltage for both receivers.
3. If the difference between the two recorded values 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
with the smaller 'on satellite' – 'off satellite' voltage difference to the controller's AGC1 input.
Connect the other receiver's Signal Strength output to the controller's AGC2 input.
4. If the AGC voltage associated with the 'on satellite' case is greater than that of the 'off satellite'
case, the receiver has POSITIVE AGC polarity (otherwise the receiver has NEGATIVE AGC
polarity). Go to CONFIG mode and use the SCROLL keys to bring up the AGC Polarity Flag item.
Key in the proper polarity using either the 0 or 1 key, and terminate the entry with the ENTER key.
5a. If two receivers are interfaced to the controller proceed to step 6. If the receiver's AGC has
NEGATIVE polarity, go to step 5b. If the receiver's AGC has POSITIVE polarity, from MANUAL
mode use the Scroll Up/Scroll Down keys to examine the signal strength for the AGC channel which
was NOT selected in step 3. If the signal strength reading for that channel is greater than 10, adjust
the OFFSET and GAIN for that channel until the signal strength reading for that channel is less than
10. To lower the displayed signal strength turn the OFFSET pot clockwise and the SCALE pot
counter-clockwise. Proceed to step 6.
5b. If the receiver's AGC has NEGATIVE polarity and only one receiver is interfaced to the controller,
connect a jumper from the controller's unused AGC input channel to connector J1, pin 11. From
MANUAL mode use the Scroll Up/Down keys to 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(s)
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 600 and 700. The
adjustments are made from MANUAL mode.
If both controller AGC ports are used, steps 7 through 9 should be performed for each channel.
Use the Scroll Up/Down keys to view the AGC channel whose pots are being adjusted.
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' (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.
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