  Since 2011 Ventspils International Radio Astronomy Centre has been involved
in the large scale infrastructure project which allowed significant speeding-up
of the upgrading activities related to radio telescopes RT-32 and RT-16 as to
its fitting with appropriate VLBI receiving and recording equipment. Radio
telescopes were instrumented with new state-of-art broadband cryogenic
receivers for frequency range of 4.5 - 8.8 GHz developed and installed by
company Tecnologias de Telecomunicaciones e Informacion. In this paper
architecture of receiving system as well as significance and working principles
of key subsystems are described. The receiver is formed by a cooled RF
subsystem and a room temperature IF subsystem. The RF and IF subsystems are
designed to process two C and X band signals (LCP and RCP) in parallel.
Normally, during observations, the measured vacuum level in the receivers dewar
is from 10e-6 to 10e-8 mbar and the temperature inside dewar is at level of 14
K at second stage, 20 K at polarizer and 46 K at the first stage. Since October
2015 radio telescope RT-32 with new receiver system took part in several
successful international VLBI sessions. During preparation for VLBI
observations preliminary aperture efficiency, system temperature and beam
pattern measurements were carried out to evaluate RT-32 performance after the
stations renovation that besides the receiver also included repairing of the
main reflector. Performance parameters were derived with the help of switching
noise diode and on-off observations of calibration sources with known flux
density at various elevations. First results measured at 4836 MHz are
summarized in this manuscript.
