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P a g e
OPERATION
Refer to Figure 4 & 5 for adjustment access location, connectors and labels
.
Variable Step Attenuator
BDA gain that indicated in the spec can be reduced by up to 30 dB in 2 dB steps using the
variable step attenuator. Gain adjustment is made with rotary switches located on the front
panel of 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, as
indicated in the specification.
ALC function is located in each power amplifier. A red LED indicator located on the Front main
panel (see figure 5) 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, and then repeat the process for the second band. 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.
Verify the downlink in-building signal strength and the uplink signal strength at donor antenna
meets requirements. Reduce the gain if needed.
Note: Operation of BDA-PS7W-37/37-90-R
at maximum gain with greater
than -30 dBm average power incidents on the MOBILE or BASE ports could
cause damage to the BDA.
