User Manual

PBL UHF 1 & 2 Air Interface
Maintenance Handbook
H/book Number:-60-055900HBKM
Issue No:-1
Date:-13/02/2003
Page:-27 of 27
5.1.3 ¼Watt 0- -30dB Switched Attenuator (10-000701)
5.1.3.1 General Application
In many practical applications for Cell Enhancers etc., the gain in each path is found to be
excessive. Therefore, provision is made within the unit for the setting of attenuation in
each path, to reduce the gain.
5.1.3.2 Switched Attenuators
The AFL switched attenuators are available in two different types; 0 – 30dB in 2 dB steps
(as in this case), or 0 – 15dB in 1 dB steps. The attenuation is simply set using the four
miniature toggle switches on the top of each unit. Each switch is clearly marked with the
attenuation it provides, and the total attenuation in line is the sum of the values switched
in. They are designed to maintain an accurate 50? impedance over their operating
5.1.4 Low Noise Amplifiers (11-006102, 11-007302 & 11-007402)
5.1.4.1 Description
The low noise amplifiers used are double or single stage solid-state low-noise amplifiers.
Class A circuitry is used in the units to ensure excellent linearity over a very wide dynamic
range. The active devices are very moderately rated to provide a long trouble-free working
life. There are no adjustments on these amplifiers, and in the unlikely event of failure then
the entire amplifier should be replaced. Note that all three amplifiers use similar DC power
circuit boards.
5.1.4.2 Technical Specification (11-006102)
Frequency range: 70 – 500MHz
Bandwidth: <430MHz
Gain: 15.5dB (typical)
1dB Compression Point: +31dBm (typical)
3rd order intercept: +46dBm (typical)
Input return loss: >20dB
Output return loss: >20dB
VSWR: Better than 1.5:1
Noise figure: <4.8dB
Connectors: SMA female
Supply: 530mA @ 10 to 24V DC (typical)
operational: -10°C to +60°C
Temperature range:
storage: -40°C to +70°C
Weight: 260gms