OK1KIR EME Team - 5.7 GHz

This picture gallery shows our equipment and system for 5.7 GHz that was used from 1994 until 2002. The first QSO was with OE9ERC on December 23rd 1994. We made 32 QSOs with it in total. The last QSO was with F2TU on November 11th 2001.

The system consists of prime focus solid Al 4m dish (chicken wire extension to 5.5m effective only on lower frequency bands) with polar mount employed semiautomatic hour angle. Moon tracking with parallax compensation and declination was aligned from time to time by manually operated screw shaft. An optical sensor mounted on dish axis was driven by small 50 Hz synchronous electrical motor via proper gear ratio and its output initiated motor of a big gear (from concrete mixer) to slowly rotate the dish polar axis to follow the Moon. Power signal with variable 50Hz frequency was divided from VXO 3.25 - 3.34 MHz. VXO frequency was manually presetted according to actual Moon orbit time. The proper declination from ecliptic plane was adjusted manually every few minutes. Already at that time we were able to use either linear or circular polarization. Linear feed was remotely rotatable to allow compensation of the polarization plane change (+/- 40°) due to polar mount as well as compensation of the spacial angle which depends on the QTH location of the other station in EME contact. Faraday rotation, fortunately, can be neglected on 6cm band. The circular polarization feed already utilized square septum polarizer. Together with self-designed sophisticated double WG switch and LNA everything was based on WGs (low loss, but quite heavy), mounted directly in the dish focus point and connected via 2m of R70 (WR137) waveguide to the TRX box placed just behind the dish center on its rear side. The linear remotely rotatable feed was placed similarly. GaAs FETs were used in one double stage LNA (1st FHX05LG). TRX box utilized transistors and varactors for multiplying oscillator frequency, Schottky diode was used for RX mixing and a step-recovery diode for TX power mixer. Mixer output was amplified by a TWT amplifier. Rf pwr of about 20W was fed via internal WG switch (RX/TX) to the WG flange on TRX front panel. This WG flange was connected to the 2m long WG towards the dish focal compartment described above. The IF 145MHz transceiver was placed on the table in the operator shack (old newspaper stand) sitting on the ground behind the dish polar tripod mount.

Terrible flood destroyed almost all of it in August 2002. Yes, it was just before EME 2002 Conference in Prague.

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