30
/ 42
User Manual
Rev. 1.0 - 12/07/20
TEX52TFT
ELETTRONICA
The amplification stage consists of two main blocks:
•
Amplification stage;
•
Low-pass filter, which also includes the power meter.
In this block there is an RF pickup at -46dB (for the
TEX52TFT
model) approximately
with respect to the output which is available on a BNC connector below the
transmitter output connector. This pickup is used to assess the characteristics of
the carrier, but not those of the upper harmonics.
7.6 Control Board
The main function of this board is to check and correct the bias voltage of the
MOSFET of the RF amplifier section.
It also provides the measurement of the absorbed current and contains an alarm
signalling circuit for the power supply unit.
This circuit also performs the following functions:
•
Control of the output power level according to the setting
•
Reduction of the power delivered in the presence of high levels of reflected
power
•
Measurement of the current absorbed by the power amplifier
•
Temperature measurement
In the absence of alarm conditions, the voltage is regulated only according to the
set output power controlled by the automatic levelling control (ALC).
Voltage is also affected by other factors, i.e.:
•
Excess of reflected power.
•
External AGC signals (Ext. AGC FWD, Ext. AGC RFL).
•
Over-temperature.
•
Excess current drawn by the RF module.
