Controller Agc Potentiometor Adjustment - Dawn CONTROL-1500A Manual

CONTROL-1500A Single Axis Antenna Controller
The controller has the provision to process two channels of AGC information. This means that
two receivers can be connected to the controller. The two channels are referred to as AGC1
and AGC2. Each channel has separate gain and offset potentiometer adjustments. The
installer uses the pots to transform the receiver's AGC signal swing into a range of values
which is easily measured by the controller.
The CONTROL-1500's AGC Polarity CONFIG mode item also influences the display of received
signal strength information. The AGC Polarity flag indicates to the controller whether a stronger
satellite signal corresponds to a higher AGC voltage (positive polarity) or a lower AGC voltage
(negative polarity). Both AGC channels must have the same polarity. Each AGC channel
contains an internal pull down resistor. This means that if one of the AGC channels is unused,
its input is pulled to ground. This can cause problems if the AGC Polarity Flag specifies
negative polarity, because an input of zero volts (ground potential) corresponds to the
strongest possible satellite signal. For this case the installer must place a jumper from
connector J1, pin 11, to the unused AGC input channel and adjust that channel's
potentiometers (after negative polarity has been specified) so that its signal strength value is 0.
J1 - pin 11 has a potential of 5.7 volts.
Signal strength information is displayed as a value between 0 and 999 at the far right of the top
row of the LCD. '***' will be displayed if the input channel is saturated. In Remote, Setup, and
Limit modes the controller displays the stronger of the two AGC inputs (adjusted for the AGC
Polarity flag).
In Manual mode, for software versions 1.5x and later, the user can hit the Scroll Up and Scroll
Down keys to display either AGC1, AGC2, or the stronger of the two AGC1 and AGC2. When
the stronger of the two inputs is displayed a blank character (' ') will be present to the left of the
signal strength display field. Similarly, a '.' character will be present when AGC1 is displayed
and a ':' will be present when AGC2 is displayed.

3.6.1 Controller AGC Potentiometor Adjustment

The following steps guide the installer through the pot adjustment process in an installation
that will operate at a single frequency band. At the conclusion of the adjustment procedure,
the displayed signal strength will vary from 50 to 100 Off Satellite to around 650 On Satellite. If
the controller is being interfaced to a receiver that will be used for both C and Ku band, the
procedure given below must be modified slightly. The modifications to the procedure for the
dual band case are described in section 3.6.1.2.
3.6.1.1 Single Frequency Band Potentiometer Adjustment
The following steps are performed when the controller is in Manual mode.
1. Align the antenna with a strong satellite. 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.
DAWNco • 3340 S. Lapeer Rd • Orion, MI 48359-1320 • Ph (248) 391-9200 • Fax (248) 391-9207 • sales@DAWNco.com
Chapter 3 Installation/Setup 27