R.V.R. Elettronica TEX150, User Manual

Page: 34 / 110

TEX150
28 / 40 User Manual Rev. 4.0 - 27/07/01
9.1 Power Supply
This circuit comprises a board, mounted on a heat sink, which is fixed to the
central part of the lower section of the unit.
The power supply generates the various stabilized voltages necessary for each of
the various modules that make up the TEX150.
The transformer has a selectable input from 110 V to 240 V and two outputs A
+18V (6.3A) and B +32V (10A).
This power supply is composed of two main parts: after having undergone filtering
for mains-borne interference, the supply is transformed into four lower voltages,
rectified, smoothed and stabilized to the following values: +12V, +15V and 10 to
28V variable to obtain the high efficiency (85-90%).
The +15V supplies the encoder mixer, the PLL card, the VCO card, the meter 100
card and the alarm card. The +12V supplies the input of RF power amplifier driver
(BGY33) and the 10-28V variable supplies the output of RF power amplifier driver
(BGY33) and the final power stage of the same module (two MRF317 or two
SD1480).
The variable voltage of the final stage is controlled by the PWR ADJ control which
determines the R.F. power output of the exciter.
The automatic control of output power guarantees the power level set by the PWR
ADJ control right across the frequency range and independantly of other variables
such as temperature, load variations etc.
The system works by comparing the value set by the PWR ADJ control with the
actual power output of the unit and compensating accordingly.
The final stage driveris composed of two separate parts, the input part is supplied
with +12V voltage, and the output part is supplied by the switching power supply
with 4-12V variable voltage obtained dividing the 10-28V variable voltage. A power
limiting circuit intervenes in the event of excess SWR on the output, thus protecting
the final stage.
9.2 Audio Input Card
This card is situated on the rear panel of the exciter.
The card filters all audio signal inputs to the unit, removing RF interference, before
supplying them to the encoder mixer or Mono\MPX card. The main operating
parameters of the exciter are available for remote monitoring via a telemetry
connector.
9.3 Coder mixer (only for stereo version)
This card is situated in the lower part of the unit.