28 Calibrating the Power Amplifier © Tait Electronics Limited February 2007
Troubleshooting Tips
DAC Settings When you adjust the DAC settings, the values for the DAC Setting, Coupler
Fwd Voltage, and Control Voltage should always increase as the power level
increases. If these values do not increase, there is either a fault with the PA or
the previous step was not calibrated correctly. If you make a mistake in the
calibration table, you must start again from step 1.
Control Voltage The Control Voltage is shown in the table to indicate the operation point
within the power control loop. The range of the control voltage is from 0 V to
7.5 V. If the control voltage reaches its limit before achieving maximum power
in the table, this indicates either a faulty gain stage in the PA or low RF input
power to the PA.
VSWR The VSWR (Voltage Standing Wave Ratio) is monitored at the RF output of
the PA during calibration. The software will not allow calibration into a load
VSWR > 1.3:1. If a calibration step cannot be stored, check that the load
VSWR is <1.3:1. It is recommended that the load should have an input
VSWR <1.2:1.
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