Notices by Neil G4DBN (g4dbn@mastodon.radio), page 3

@f4grx He's developing into a brilliant cross between Styropyro and ElectroBOOM. I have questions about the treatment of capacitance and ignoring leakage inductance in the mains transformer. I worry hugely about the effects on his corneas and perhaps earlobes and nose tissues. Corneas and eye tissues in particular though. He didn't really get into the physics of coupling into the waveguide. I have some 80 kW pulsed magnetrons on my desk right now. This video inspires me to try crazier stuff!

@jmorris @azonenberg I'm going to try to get to Seattle next year when I'm giving a lecture at a Microwaves conference in Vancouver. I want to visit the Connections Museum in Seattle and meet some microwave folks in the area

@jmorris @azonenberg I tend to prefer making the feedhorns - usually Pickett-Potter dual-mode or with integral chokes or septums. Wideband transitions almost always need to be made in two halves to get the sharp corners to mate with rectangular waveguides. I can do centrifugal casting, but getting a good enough finish is tough. Oval iris narrowband transitions are easy enough of course, I can make those on the manual mill. SMA, N and 3.5/2.91 mm transitions to w/g are always popular

@jmorris @azonenberg of course what I REALLY need is a wire EDM machine and a die sinker

@jmorris @azonenberg Definitely, I'll mostly be building up a stock of popular parts for sale rather than doing a lot of custom work, but it's only a matter of scale. I can do gold/silver plating, anodizing, laser marking, electroforming and casting, so most things are possible other than precision dishes more than about 230 mm diameter. Once I get the lathe modified for one-axis CNC, I should be able to make large cast aluminium dishes up to 18 inch diameter, but 12 inches is easier

@azonenberg The main driver was so I could machine elliptical and offset-parabolic reflectors, plus things like laterally-displaced ellipse Gregorian antenna systems at mmWave frequencies, and slot arrays with hundreds of elements. The stress of doing manual machining for even a 2 x 24 slot array at 10 GHz is way too high, so 100+ precision slot arrays are best done on machines. Same with making batch runs of waveguide parts

@g0fcu @g7vkq @2m0sql By the time you take into account the tooling, vices, probes, induction shrinkfit thingy, transport, installation, training, compressor, fancy coolant, 3 phase inverter and building mods, the total cost is the wrong side of £40k. It should pay for itself over a few years though

@Dtl I rather imagine she'll either be very sniffy, or go full-on nerd-out about it

My new Syil X5 CNC mill is ready to ship from the factory. Might be here by New Year if I'm lucky. This is it, just completed QA testing

@jmorris I'm having a few nightmares with material distortion at the moment, but I'm thinking of printing a large Luneburg lens in segments so I can test it more thoroughly. I'm trying to do 100 things at once though, and just wasted four hours trying to fix my old RasPi 3 running dump1090 for an ADSB feed to an aggregator to use in aircraft scatter communications. Turns out the image was SO ancient (wheezy), it was nearly impossible to upgrade. However, it is now shiny and lovely again. Phew!

First try at printing a gradient-index lens based on a variable wall-thickness gyroid lattice with the lattice surface meshes calculated using MATLAB code, then stitched and repaired, imported into Fusion 360, smoothed and then exported as STL into Prusaslicer and printed in PLA on the MK3S+ in the Prusa Enclosure.