overhead view 23:20 utc East Yorkshire
| LOC | IO93NR |
| Website | www.g4dbn.uk |
| Youtube | https://youtube.com/MachiningandMicrowaves |
| @g4dbn |
Neil G4DBN
- 408 Followers
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Radio ham since 1973. DC to light. Youtuber (Machining and Microwaves) Hacker, machinist, maker of Things, Infosec CTO, basketmaker, carpenter, Chihuahua herder, sceptic. East Yorks UK
Oh my good gracious. Lawks amercy. Gosh all hemlock and stap me vitals! Who would ever have thought that anyone would want to watch me spouting nonsense and waving my arms about on the Chube. The World has gone entirely bonkers. Only two to go and I'll be half way to getting a cheap-looking plaque. One and a half cheers!
bit of pink sky to the north at 01:32 local, still weak aurora but I need to get to bed now
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
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
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
This is roughly how the arms are used, but with the dish inclined at 18.9 degrees to the vertical rather than pointing at the zenith. Dish is 230 x 250 mm, made from 3/4 inch aluminium plate. The heaxagonal pockets are milled out to save weight but retain stiffness. The dish surface is accurate to about 20 micrometres, with 4 micrometre ridges from the spiral machining using an 8mm ball-ended carbide mill at 11500 rpm and 2800 mm/min on my SYIL X5 CNC mill #hamradio
First attempt at a carbon-fibre-filled PLA support arm (one of a pair) for the milled-from-plate offset parabolic 122/134/248 GHz mmWave antenna dish. The left end attaches either side of a block bolted to the threaded holes behind the dish. The face is inclined at 18.9 degrees so points at the horizon with the bottom edge horizontal. The four mounting holes at the right end bolt to the enclosure containing the radar chip, focus rail, control electronics and feedhorn. Bit of Voronoi for bling.