User's Manual

BDA OPERATION
Refer to figure 3 for adjustment access location and label.
Variable Step Attenuator
BDA gain can be reduced by up to 30 dB in 2 dB steps using the variable step
attenuator (Figure 4). 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 +31 dBm.
The ALC function is integrated in each amplifier. A red indicator lamp located on each
amplifier illuminates when output power exceeds the ALC set point.
To establish proper operating gain on the Uplink and Downlink sides, start with the
Downlink. Verify that the attenuation is set for 30 dB. Observe the red indicator lamp
on the Downlink amplifier. Units are shipping with maximum attenuation. Decrease
attenuation one step at a time until the lamp is lit. Then, increase the attenuation until
the lamp goes off. Repeat the process for the Uplink. The level indicator is accurate
to +/- 0.4 dB of the ALC set point.
Operation of BDA-UHF-4/4W-70-A at minimum attenuation with greater than
-25 dBm average power incident on either BASE or MOBILE port can cause
damage to the BDA.
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