OK1KIR EME Team - 10 GHz, Our Old System

This picture gallery shows our equipment and system for 10 GHz that was used from 1993 until 2002. The first QSO was with SM4DHN on October 10th 1993. We made 35 QSOs with it in total. The last QSO was with OK1UWA on June 6th 2002.

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 around 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 shows no influence on 3cm band signals. The circular polarization feed already utilized square septum polarizer. Together with self-designed sophisticated double WG switch and two LNAs connected in series everything was based on WGs (low loss, but quite heavy), mounted directly in the dish focus point and connected via 2m of R100 (WR90) waveguide to the TRX box placed just behind the dish center on its rear side. The linear remotely rotatable feed was placed similarly. Both home brew LNAs utilized GaAs FETs (NE325 on the input stage). TRX box used transistors and varactors for multiplying oscillator frequency, Schottky diode for RX mixing and a step-recovery diode for waveguide TX power mixer followed by a TWT amplifier. Its about 15W of rf pwr 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 inside 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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