Upgrade to 3.4 GHz Microwave Station for EME
Recently the FRARS 3.4 GHz system has undergone considerable work to upgrade its performance for EME.
The system now has a fully GPS referenced, frequency locked transverter based arrangement, based on a Down East Microwave design.
A 3.4 GHz LNA has been acquired from Sam G4DDK and a waveguide based Interdigital filter has been produced to provide roofing bandpass characteristics. This is followed by a second stage GaAsFET LNA feeding the transverter.
The power amplifier is based on an identical pair of 30W ex Telecom modules, each supplied by a head plate mounted 240 volt mains input switched mode power supply. After a lot of work it now outputs approximately 55 Watts of CW. Shack based power monitoring is available and the complete system is driven from an IC746 and WSJT-x.
During the enhancement process, HB9Q was worked just before 3.4 GHz was withdrawn by the Swiss authorities. (see separate article) and now several other QSOs to other countries have been logged using the enhanced system.
The final act to complete the system has been to mount the umbilical connected transverter onto a new weatherproof plate housing at the rear of the dish.
Article by John G0API, 16 May 2024.