R.V.R. Elettronica PTX30-UHT, Инструкция по установке, техническому обслуживанию и ремонту, Страница: 16 / 171

PTX30-UHT Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 16
CHAPTER 2
ELECTRICAL DESCRIPTION
2.1 INTRODUCTION
This section describes the general working theory of PTX30-UHT.
For utility, the device is divided in subassemblies that will be deeply
discussed in the following paragraphs.
For the block diagram of the transmitter see Fig.3A for "EUROPA" version,
and Fig.3B for "U.S.A." version.
2.2 POWER SUPPLY
This circuit is composed of two boards placed over two heat-sinks
perpendicularly mounted, fitted in the central part of the intermediate
plate (8 Photo 1). The power supply generates the stabilized voltages
needed by the various modules that composes PTX30-UHT.
The mains voltage, after passing an EMI filter is transformed in to 4
lower voltages that rectified and filtered are stabilized to the final
values of +5V, +12V, +15V, -15V and a variable voltage ranging from 2
to 24V.
The +5V line supplies the CPU board, the +15V and -15V lines supply the
coder mixer, the main card, the modmeter the CPU board and the anameter
boards 1 and 2.
The +12V line supplies the driver stage of the RF power amplifier and
the variable voltage (2-24V) supplies the final stage of the Power
Amplifier.
The variable voltage applied to the final stage is regulated by the
external control "PWR ADJ." and sets the exciter output power value.
The automatic output power control, guarantees prefixed output power
level through the PWR ADJ command, and over the entire frequency range
and for the variation of the operating parameters of the exciter, example
temperature, SWR.
This regulation is obtained comparing the voltage setted by the "PWR ADJ"
against the voltage obtained from the internal power meter.
An output power limiter acts when the SWR becomes too high, saving the
life of the final stage.
The above mentioned voltages and currents are measurable by the built-
in analog meter.
2.3 MAIN CARD
The main card (2 Photo 1) is situated internally, on left of the
unit’s bottom.
The circuit includes a voltage-controlled oscillator (VCO) which
generates the selected operating frequency.
This signal is amplified to drive the phase-locked loop (PLL) control
circuit and also the final stage.