Rohde & Schwarz Inc TMU925 用户手册
Amplifier R&S PMU901
R&S
®
TMU9
85
System Manual 2600.5423.02 ─ 01
A soft start is performed as soon as the input signal returns. The selected threshold is
such that the amplifier can be reliably operated across the entire temperature range in
all permissible operating modes, even at the lower tolerance limit of the RF_IN input
signal at X10.
such that the amplifier can be reliably operated across the entire temperature range in
all permissible operating modes, even at the lower tolerance limit of the RF_IN input
signal at X10.
Output power limitation
The output power is set by means of the VREF_PWR signal. The output power is limited
such that the amplifier cannot be damaged at excessively high VREF_PWR values. In
addition, the average output power of the amplifier is also limited by means of hardware.
Excessive power if the forward power test point fails as well as subsequent failures if a
transistor fails are countered by the intelligent control brake.
such that the amplifier cannot be damaged at excessively high VREF_PWR values. In
addition, the average output power of the amplifier is also limited by means of hardware.
Excessive power if the forward power test point fails as well as subsequent failures if a
transistor fails are countered by the intelligent control brake.
Temperature monitoring and fan control
The power supply units and amplifier circuit each have a dedicated hardware overtem-
perature shutdown mechanism. If a temperature threshold is exceeded, the amplifier is
disabled (TEMP_FAIL message), whereby the threshold for the overtemperature shut-
down is above the permissible operating temperature. This ensures that the remaining
overall power loss does not lead to overheating of the instrument, even with total failure
of the cooling system.
perature shutdown mechanism. If a temperature threshold is exceeded, the amplifier is
disabled (TEMP_FAIL message), whereby the threshold for the overtemperature shut-
down is above the permissible operating temperature. This ensures that the remaining
overall power loss does not lead to overheating of the instrument, even with total failure
of the cooling system.
The fan has four different speed settings, whereby the second speed is the standard
speed which has been optimized with regard to the average junction temperature of the
output stage and to noise generation.
speed which has been optimized with regard to the average junction temperature of the
output stage and to noise generation.
To ensure that transmission can continue for as long as possible, the temperature and
fan control functions work together as follows:
fan control functions work together as follows:
● If the temperature rises in the amplifier circuit, the fan speed is first increased before
the hardware shutdown threshold is reached.
● If this is not enough, at temperatures above 83 °C the amplifier control begins to
reduce the output power in steps of 1 dB (DTV only, REDUCED_PWR message).
● With ATV, the output power is not reduced at excessively high temperatures. Instead,
the amplifier is shut down by means of software at 85 °C.
● At temperatures above 90 °C, the amplifier remains switched off by means of hard-
ware for as long as the overtemperature exists. Overtemperature on the amplifier
board is indicated by means of the front TEMP FAIL LED (with ATV: at 85 °C and
higher).
board is indicated by means of the front TEMP FAIL LED (with ATV: at 85 °C and
higher).
● An appropriate hysteresis is integrated to prevent deactivation and activation from
occurring too soon. A soft start is performed as soon as power returns.
In addition, the inlet and outlet temperature is measured by means of two sensors (on
the front and rear side of the amplifier board, thermally insulated from the rest of the
printed board). This allows, for example, a fouled air filter to be detected and changed in
good time (AIR_FILT_FAIL message).
the front and rear side of the amplifier board, thermally insulated from the rest of the
printed board). This allows, for example, a fouled air filter to be detected and changed in
good time (AIR_FILT_FAIL message).
Reflection monitoring
A distinction is made between the following types of reflection monitoring (REFLECTION
message):
message):
Design and Function R&S PMU901