Pulsar LPA100, Системное руководство

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Copyright © 2001 Pulsar Technologies, Inc.
Chapter 2. Applications and Ordering Information
2
2.1 LPA50/LPA100 Applications
The LPA50 and LPA100 are used in applications
where the losses between the transmitting and
receiving carrier sets are greater than a 10 W
system can handle. Usually this is due to high loss
on the power line because of an extremely long
line, underground cable, or a combination of
underground cable and overhead lines.
We recommend that before applying a high power
linear power amplifier (LPA), you do a thorough
analysis of the expected power line loss, including
all tuners, hybrids, coupling capacitors, etc. You
can often decrease total loss in a system by
properly tuning the line, using the optimum
hybrids for the application, removing any unnec-
essary attenuators in carrier receiver sets, and
selecting the proper carrier frequency. Using the
lowest possible carrier frequency (generally 30-50
kHz) is especially important on underground
cables, as their loss significantly increases at the
higher frequencies.
When applying high power LPAs, you must treat
the following three types of systems differently:
• Directional Comparison Blocking systems
• Phase Comparison Blocking systems
• Systems using frequency shift carrier sets
2.1.1 Directional Comparison Blocking
systems
For Directional Comparison Blocking systems,
where the receiver can hear its own transmitter
without any problems, you do not need to connect
hybrids between the output of the LPA and the
local receiver. Also, you should bridge the
receiver of the local carrier set directly to the
output of the LPA. See Figure 2-1. You can only
bridge the carrier receiver across the output of the
LPA100 if it is capable of sustaining 70.7 Vrms
across its input without saturating. When using a
TC-10B in a blocking system, you should set up
the TC-10B for 4-wire operation (separate
transmit and receive paths) and set the receiver
sensitivity jumper to NORM. This means that on
the RF Interface Module you would set JU1 and
JU5 in the OUT position to give 4-wire operation
and JU6 to NORM to give 13 dB of attenuation to
the incoming local transmit signal.
Tx
LPA
To
Line
Tuner
Rx
Tx
LPA
H1SB-R
To
Line
Tuner
Rx
Fig. 2–1. TC-10B with LPA RF connections.
Fig. 2–2. TC-10B (Analog Receiver) or TCF-10B
RF connections.