Last Updated on March 5, 2026 by John Berry
My UHF station 432MHz is textbook for EME – four 14-element 70cm14DX3 Yagis from Antennas-Amplifiers on a 5-metre steel pole. These are combined through a four-port half-wave combiner. Then fed to an SSB SL70 Electronic low noise amplifier.
The figure of merit for my antenna system – the log of the ratio between noise from the Sun (when pointing at the Sun) to noise from the quiet sky (when pointing away from the Sun) – is about 6dB. So quite good. More detailed calculations will tell if this can be improved. And my own echoes from the Moon come in (on a good day) at about -19dB below the 2.5kHz channel noise. Again quite good.
The rotator is a Yaesu G-5500. Feeder to the shack is 30m of Andrew LDF4-50A low loss feeder.
The antennas track the Moon using a Python program developed by me (and Gemini AI) based on an ON4KHG script. This program interprets AzEl data from the WSJT-x application.
The code drives an ERC-DUO USB-Yaesu rotor interface driving the rotator via the rotctld daemon in hamlib.
The rig is an IC9700 and I use a DX Shop PTT multiplier because Icom hasn’t split out the PTTs for each band! Then finally an SSB DCW 2004 B Sequencer with bias-T to the LNA.
Then 100W 2m PA centre and 6m and HF 500W PA right with sequencers.
I use a homebrew 500W LDMOS power amplifier based on W6PQL boards, with 50W drive from the IC9700 on modes like Q65. The amp delivers 500W RF to realise about 400W at the antennas.
Some time in the future I may add higher antenna gain, and crossed Yagis and polarisation switching. I’ve yet to decide if the benefits outweigh the cost.