User's Manual

UHF BI-DIRECTIONAL AMPLIFIER TECHNICAL MANUAL
5
Specifications
Our UHF amplifier have been designed with government agencies in mind. These are our highest level
of performance and quality for continuous duty solutions while providing maximizing coverage.
Available in rack mount, nema stainless steel, or painted steel nema enclosures.
Block Diagram Details
- The Downlink path receives signals from the donor antenna, and then amplifies them as they
pass through the unit to the distribution system.
- The Uplink path receives signals from the distribution system, and then amplifies them as they
pass through the unit to the donor antenna.
- Uplink and Downlink paths contain each a Variable Gain Amplifier (VGA) followed by a fixed
gain Power Amplifier (PA). A mid-stage access allows channel filter to be inserted, in order to
reject adjacent channel signals and to improve the main signal quality.
- The VGA is basically a low noise amplifier featured Automatic Gain Control (AGC) circuit . The
AGC circuit measures composite power level at the VGA input and adjusts automatically the
gain, in order to maintain constant the signal level at the VGA output. Since the VGA output
power is constant, the PA composite output power is also maintained constant at the factory set
level.
- The VGA provides also Input Level Adjustment and Output Power Setting by mean of two
Manually Set Attenuators (MSA#1 and MSA#2).
The MSA#1 allows additional attenuation and hence maintains the VGA under linear condition
if the input signal is too strong ( greater than -25dBm). It is also used for adjusting the input
signal to the optimum level (please see VGA Max Input Level and Optimum Input Level Setting ).
The MSA#2 attenuator allows to adjust the VGA power, thus the PA output power can be also
changed to the desired level, which can be differed to the factory set level. An MSA#2 setting
table vs. VGA output power is supplied with the unit. The PA linear gain is also provided.
- The Class-AB PA provides good performance for both linearity and efficiency. This amplifier is
heat sink mounted and produces a high compression point and 3
rd
order Intercept point.
- The Power Supply bloc converts AC to DC voltages for supporting DC power needs of both
Uplink and Downlink amplifiers.
- The unit can accept 50/60Hz 100 to 260 Volt AC power source, but does not have UPS/Battery
system. In case of need for inconsistency in the AC line power, surge protection, short Black
outs, crossover time from line AC to generator power, circuit breaker for short circuit and over
load protection, etc., an external UPS/Battery system is recommended.