TEX1000-LCD
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User Manual
Rev. 1.1 - 23/06/05
Moreover, in the end of filter, there is a directional coupler, its function is the
measurement of the forward and reflected output power.
On this card there is an RF sample at -60dB compared with the output and it is
available on a BNC connector. This sample is useful for checking the characteristics
of the carrier, but not of the higher order harmonics.
8.10 BIAS card
Main function, of this card, is to check and to correct the polarization voltage (BIAS)
of Mosfet in RF amplifier section.
Moreover it supplies the measure of the absorbed current as sum of the absorbed
currents from every module and it contains a circuit for the signalling of the breakdowns
in the Power Supply.
Without alarm condition, Bias voltage is regulated only in function of output power set
up, with a feedback mechanism based on the reading of the effectively distributed
power (AGC).
Bias voltage is also influenced from other factors like:
- Excess of reflected voltage
- External AGC signals (Ext. AGC FWD, Ext. AGC RFL,...)
- Excess of temperature
- Excess of absorbed current from a RF module.
