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OPERATION:
Refer to Figure 3 & 3a for adjustment access location, connectors and labels.
Variable Step Attenuator
BDA gain can be reduced by up to 30 dB in 2 dB steps using the variable step
attenuator. Gain adjustment is made with rotary switches accessible via the access
door on the BDA enclosure. Arrows on the shafts of these switches point to the value
of attenuation selected. BDA gain can be determined by subtracting the attenuation
value from the gain reported on the BDA Test Data Sheet for that side of the unit. The
attenuators are labeled for Uplink and Downlink.
ALC (Automatic Level Control)
To minimize intermodulation products, each amplifier in the BDA contains an ALC
feedback loop. The ALC circuit senses the output power and limits it to the factory
preset level of +33 dBm
UL and +33 dBm DL.
ALC
function
is located in each power amplifier. A red LED indicator located on the
Front main panel (see figure 3) illuminates when output power meets or exceeds the
ALC preset point.
To establish proper operating gain on the Uplink and Downlink sides, start with the
Downlink. Observe the red LED indicator on the Downlink amplifier. Units are shipping
with maximum attenuation. Decrease attenuation one step at a time until the red LED
is lit. Then, using the Downlink step attenuator, increase the attenuation until the red
LED goes off. Repeat the process for the Uplink. . This setup should be done under
RF signal transmit for either path the level indicator is accurate to +/- 0.4 dB of the
ALC set point.
