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User's Manual

ManualsBrandsP.G.Electronics ManualsElectronicsDual Band Bidirectional Amplifier
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P.G. TM0032FE
2 - 1
SECTION 2. THEORY OF OPERATION
2.0 GENERAL
As explained in Section 1, the A211 is a bidirectional amplifier, which provides 20 dB of
gain in both the cellular and PCS wireless transmit and receive bands. The block
diagram of the A211 is shown in Figure 2-1.
2.1 DESCRIPTION
2.1.1.
- The unit is composed of two diplexers, two independent bidirectional amplifiers
and alarm and voltage regulation circuits.
2.1.2.
- The diplexers U1 and U2 divide power between the cellular and PCS
bidirectional amplifiers. In each bidirectional amplifier additional bandpass diplexers
separate signals for the uplink and downlink amplifiers.
2.1.3.
- The bias condition of each device in the amplifiers is monitored. If the bias
changes outside certain limits a fault condition is indicated. The downlink RF output
power in each band is also monitored. If the power in either band drops below
established limits a FAULT condition is indicated.
When a FAULT condition occurs the unit transmits the unit identification (or "Fault
Code") by two level amplitude modulation of a low frequency carrier placed on the cable
center conductor. The signal is transmitted as a short burst repeated at approximately
80 second intervals while the fault condition persists. The fault code can be
reprogrammed as described in Section 3.2. While a NORMAL condition exists the
amplifier transmits an OK code at intervals of approximately 80 minutes. This remote
status transmission feature is not available when the unit is configured for local powered
operation.
2.1.4.
- The voltage regulators take 15 - 24 VDC input and provide 12 VDC and 8 VDC
outputs. A zener diode provides transient protection against voltage spikes on the
cable.
2.1.5.
- The standard A211 dual band bidirectional amplifier requires external DC
power to be supplied through either one of the two N receptacles. Internal jumpers are
used to select whether DC current is drawn from J1, J2 or both. If configured to draw
current from J1 or J2 then the unit will only pass RF between J1 and J2. Otherwise the
unit will pass both DC and RF. Section 3.2 provides details on how to set up these
jumpers.
The local powered unit is configured to block DC to J1 and J2. The PS217 external
power source is used to supply DC power to the unit.