10 GHz sun noise test
Aug 24, 2024
Over the last couple of months I’ve managed to make some more progress with the small 10GHz station. I now have a simple dish support with elevation control using a linear actuator but azimuth control is still manual. I have also added a WR75 waveguide switch, DU3T LNA from PA0PLY along with a new linear feedhorn.
After assembling the feedhorn, waveguide switch and LNA on the feed tray I remembered that 10GHz EME operators in Europe use vertical polarisation. I initially thought about using a short section of waveguide with a 90 degree twist but managed to find a suitable bracket to mount the switch with the correct orientation. The feed tray looks oversized at the moment but I still need to add a small driver amplifier and Kuhne SSPA that I recently bought.
I used my Arduino Nano/Si5351a 10GHz signal source to get the feed tray in roughly the right place and then moved on to taking some sun noise measurements using a SDRplay RSP1a, HDSDR and SpectraVue. Initial results were poor, the best Tsky/Tsun was around 4dB whilst VK3UM EMECalc was showing 8.6dB. A string test indicated that the feedhorn was too high so I repositioned the feed tray on the feed arm. After some further adjustments Tsky/Tsun improved to 7dB, SFU @ 10.368GHz = 401.
With the microwave section of the ARRL EME contest this weekend I’m hoping for some dry weather to test the receive capability the setup.