I’ve just completed a batch of 24 of these W2IMU feedhorns for the 122 GHz band. Thread as usual is M8 x 0.5 mm. Horn ID is 4.03 mm, 27.1 degree internal flare, 2.00 mm reamed waveguide core, rear duplexer cavity for VK3CV boards, four M2 threaded holes, 4.00 mm reamed barrel, 3.98 mm spigot on the waveguide. This is the version 2 with a flat step as the end stop. Rather than relying on the 7.5 mm tapping drill to make the bottom of the threaded section, I now machine that using a centre-cutting M7 end mill. Part number for this version is DBN-122-IMU-0.7-02 and price to bona-fide 122 GHz experimenters is £14
One of the main contests of the year for me is the CQ Worldwide 160 metre CW (Morse code) competition at the end of January. Here is a snapshot of the activity between 1810 kHz and 1900 kHz. The section around 1842 kHz is FT8, and there is a little WSPR traffic just above 1836.
I had enormous fun with a compromise antenna and only 5 watts from my FDM-DUO SDR, but I worked plenty of US stations as far as Texas and Ohio. Click the [ ] to show it full-screen