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   Neil G4DBN (g4dbn@mastodon.radio)'s status on Wednesday, 19-Jun-2024 11:45:33 JST Neil G4DBN

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   Here's one of the smaller Edmund parabolic dishes. This is the 12 inch/300 mm version. These take a 48 mm diameter Cassegrain sub, the 18 inch/450 mm versions take a 68 mm sub and the 24 inch/600 mm versions take a 98 mm sub and need rather stronger mountings, 6mm carbon fibre tube instead of 4mm pultruded CF rod. Shiny! #hamradio

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     Neil G4DBN (g4dbn@mastodon.radio)'s status on Wednesday, 19-Jun-2024 11:45:34 JST Neil G4DBN

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     And this is what the printed Thing is for. Three carbon fibre rods flare outwards from the three sockets and go through metal sleeves to a support ring behind the dish. There's an M12x0.5 mm thread inside the hyperbolic sub for fine focus adjustment. One turn is a fifth of a wavelength at 122 GHz #hamradio

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     Neil G4DBN (g4dbn@mastodon.radio)'s status on Wednesday, 19-Jun-2024 11:45:35 JST Neil G4DBN

     Mysterious Things appearing on my Bambu X1C. Spiders to support hyperbolic Cassegrain subreflectors in the very deep Edmund Optics 18 inch parabolic dishes with f/d 0.25, so the focal point is at the same height as the dish rim. Total pain to illuminate unless you set it up as a Cassegrain, with the feedhorn phase centre right at the dish face centre orifice. These are for 76,122,134 and 248 GHz #hamradio

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