User's Manual
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BDAOperation:
Refer to figure 4 for adjustment access location and label.
Variable Step Attenuator
BDA gain can be attenuated, for Uplink and Downlink separately, up to 31 dB in 1 dB
steps using the variable step attenuator (Figure 4). To adjust the attenuation up to 11
dB, use the dialer on the front panel. To adjust the attenuation up to 31 dB, set the
thumbnail switch to +10 dB, and then dial in the remaining attenuation via the dialer.
BDA gain may 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.
Attenuation System Gain Attenuator Position
0 80 Both thumbnail switches
down and the dialer on zero
5 75 Both thumbnail switches
down and the dialer on five
10 70 Both thumbnail switches
down and the dialer on ten
15 65 One thumbnail switch up
and the dialer on five
20 60 One thumbnail switch up
and the dialer on ten
25 55 Two thumbnail switches up
and the dialer on five
31 49 Two thumbnail switches up
and the dialer on eleven
Table 2
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.
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 31 dB (minimum system gain). Observe
the red indicator lamp on the Downlink amplifier. Units are shipped 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.