Tait TB8100 Service Manual

118 Power Amplifier Circuit Description TB8100 Service Manual
© Tait Electronics Limited September 2006
7.1.4 Shutdown
The PA software will prevent transmission under the following conditions:
■ the following calibration procedures were not completed successfully:
■ 6W driver transistor, 60W final transistor 1 or 60W final
transistor 2 bias
■ detector bias
■ supply voltage
■ output power
■ the supply voltage drops below 24VDC or exceeds 32VDC
■ the transmit current of the 6W driver and 60W final transistors does not
reduce to a safe level after foldback
■ the configuration of the PA is invalid.
7.1.5 Power Control
The PA has a power control circuit which keeps the output power constant
and protects the PA from VSWR mismatch conditions. The control circuit
monitors forward and reverse power and these measurements are used to:
■ determine forward and reverse power
■ keep the output power constant
■ foldback the power under mismatch conditions
■ calculate VSWR.
The power level is set by requesting the power level in watts via an I
2
C bus
message. The minimum size of a power step is 1W and the range of output
power settings is:
The forward power, reverse power and load VSWR measurements may also
be requested via I
2
C bus messages.
The foldback loop is analogue until the VSWR reaches 10:1, at which point
the microprocessor initiates foldback.
The microprocessor and control loop are also used to shape the RF signal
envelope during key-on and key-off transients.
Model Output Power Range
5W 1W to 5W
50W 5W to 50W
100W 10W to 100W

Tait TB8100 Specifications

General

Brand	Tait
Model	TB8100
Category	Accessories
Language	English