Comtech EF Data TRP500 - Manual (Page 7)

Updates to Firmware for Over Temperature and Overdrive Awareness
AD-TRP500-AA1 Revision – (This document is not subject to revision/update.)
3
Overview:
New units, or units returned to the factory for repair or upgrades after August 2013, will have the firmware
updated to help the user be more aware of potential over temperature and over drive conditions that
could degrade the reliability of the amplifier. Furthermore, the user will be able to view recorded
maximum and minimum values of important parameters as they have occurred over the operating history
of the unit. These updates are explained below, and may supersede information in other sections of the
manual.
Over Temperature:
As stated in the specifications, the amplifier is rated to operate up to ambient temperatures of 60C.
Operating temperatures beyond this rating may degrade the performance and life of the amplifier. The
unit has an internal sensor that monitors the temperature of the airflow across the cooling fans, and is
very close to the actual ambient or outside temperature. This temperature can be monitored on the
Status webpage, where it is labeled Outside Temperature (see Figure AD-1 below). It is also reported via
the serial RMS command, and has the label of OTEMP. This temperature should be consistent with the
expected ambient temperature in which the unit resides. If it is not, then the user should try and ensure
that there are no obstructions blocking the cool air inlet or recirculating the hot air exhaust of the unit back
into the inlet, that there is adequate clearance around the cool air inlet and exhaust areas, that all fans
are working properly, etc.
If this Outside Temperature sensor rises above 65C, or other internally monitored temperatures exceed
their threshold (such as Atemp>95C), an alarm or fault will be declared. The unit will not shut down but
the condition causing the elevated temperature should be promptly remedied. If temperatures continue to
rise (Outside Temp>70C or Atemp>100C), the unit will declare an Over Temperature Shutdown fault and
will turn off the 10V supply to the critical RF transistors for protection purposes. Figures AD-2 and AD-3
show these conditions. (The Amplifier/Outside Temperature Alarm has a hysteresis of 5C, while the Over
Temperature Shutdown fault has a hysteresis of 10C).
Over Drive (excessive RF input level):
As stated in the specifications, the amplifier is guaranteed to deliver at least 56.2 dBm of power at the
P1dB compression point. Although the unit may be capable, operating much beyond this 56.2 dBm level
is discouraged. As the input drive level is increased, output saturation will soon be reached where device
currents and temperatures may rise very quickly to disconcerting levels, but without any effective or visual
increase in overall unit output power.
Although the best protection against potentially degrading overdrive conditions is user attention and
vigilance to the input and output levels as mentioned above, Comtech has implemented software updates
that will help self-protect the unit and warn the user of gross overdrive conditions. This Overdrive alarm is
visible on the Status webpage as shown in Figure AD-4. The unit begins adding attenuation at estimated
excessive input levels and will eventually declare the visible alarm when this estimated level is at or
above 1.2 dB. If this occurs, the user should reduce input power until the alarm clears and the estimated
overdrive is 0 dB. (Note: Once the alarm is activated, for hysteresis purposes the input power must be
reduced until the estimated overdrive is 0 before the alarm will clear. This reduction may need to be as
much as double the amount of overdrive because the unit releases attenuation as the input power is
decreased). Power Supply currents are also displayed (PS1 and PS2).
Maximum Operating Points:
The Status webpage has been updated to include the maximum (and in some cases, minimum) operating
points of key parameters as they are recorded by the unit over time.