Boost Regulator Circuitry (12V Pa Only) - Tait TB8100 Service Manual

7.3

Boost Regulator Circuitry (12V PA Only)

Power Saving
Operation
122 Power Amplifier Circuit Description
5W and 50W 12V PAs are fitted with a boost regulator board.
on page 114 shows the configuration for a 50W PA, along with the main
inputs and outputs for power, RF and control signals. Note that the 60W
board is only fitted to the 50W PA.
The boost regulator board accepts an input of 12VDC nominal. The input
is firstly fed through the DC input filter, and then through an output filter
and switch which is controlled by a battery control circuit. This output is
fed to the reciter, which operates from 12VDC instead of the standard
28VDC provided when a PMU is used. The output from the DC input
filter is also fed to the power stage where the voltage is boosted to 28VDC,
and is then fed through an output filter to provide the 28VDC output for
the PA circuit boards.
The battery control circuitry monitors the DC input voltage from the
battery. Protection is provided against the wrong input voltage being
supplied. Reverse polarity protection is provided by a diode between
positive and ground, and requires a user-provided fuse or circuit breaker in
series with the DC input line. The fuse or circuit breaker should be rated
at 15A to 18A at 30VDC.
The startup voltage is 12VDC or higher. Once started, the boost regulator
will operate down to 10.5VDC ±0.25V before it shuts down to prevent
deep discharge of the battery.
Note
These limits are set in hardware at the factory and cannot be
adjusted by the user.
Power Saving is also available in base stations using a 12V PA. Both Sleep
and Deep Sleep modes can be configured, with the same receiver cycling
and Tx keyup options as a base station with a PMU. In Deep Sleep mode,
the reciter shuts down the PA by shutting down the boost regulator board
in the PA (via an external control cable
page 292). The 12VDC output from the boost regulator board is
unswitched and continues to power the reciter even when the rest of the
circuitry on the board is shut down.
1. Refer to the TB8100 Installation and Operation Manual (MBA-00005-xx)
for more information on this connection.
1
, as shown in Figure 19.4 on
TB8100 Service Manual
© Tait Electronics Limited September 2006
Figure 7.1