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1.3.10.3
Over Drive (Excessive RF Input Level)
The unit's specified linear rated output power level, Plinear, can be found in the unit datasheet. Although
the unit may be capable, operating beyond its Plinear 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 appreciable increase in usable 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, CEFD has implemented software failsafes
which will help protect the unit from damage and warn the user of gross overdrive conditions. The over
drive information is displayed on the Status webpage.
When an excessive output power level is detected, the unit begins adding attenuation and will eventually
declare an alarm when the over drive condition exceedes 1.0 dB. If this occurs, the user should reduce
the input power until the alarm clears and the estimated overdrive is 0 dB. (Note that once the over drive
alarm is active, the input power level must be reduced until the output power is 5 dB below the Prated
level before the over drive attenuation is released and the alarm is cleared.) Additionally, a fault condition
is raised if the over drive attenuation level reaches 10 dB. This fault will turn off the power supplies to the
critical RF transistors for protection purposes.
1.3.11
Maximum Operating Points
Chapter 4. ETHERNET INTERFACE OPERATION, Section 4.5.4.2, Status | Status
The Status | Status webpage includes the maximum (and in some cases, minimum) operating points of
key parameters as they are recorded by the unit over time. This helps the factory and the user ensure
that the unit is being operated correctly, especially regarding ambient temperature and user drive levels.
1.3.12
Power Supply
The LGaN features a power supply that is power factor corrected. It supplies several voltages necessary
for the unit to operate.
1.3.13
LNB Operation
Either LGaN package style may be ordered with an optional internal 10 MHz reference and LNB
converter bias tee. With these options installed, the user has control of the bias tee enable (LNB On/Off)
as well as the DC bias voltage (On/Off).
Introduction
1–5
L-GaN
Revision 0
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