Notices by Neil G4DBN (g4dbn@mastodon.radio), page 2

I paid DHL ludicrous money for an urgent delivery from Italy. It arrived in the UK very rapidly, cleared customs (bargain £11 ransom fee) and was out for delivery by 8am. It was 12 miles away when it was supposed to be delivered at 10 AM. Six hours later and it's now 13 miles away. DHL: "Sorry, we're running late". That makes two of us pal. #dhl

Update: the order eventually arrived SEVEN hours late. That means I missed the last shipping time so the Things might not be with the customer before the Friday deadline. Super service from the supplier in Italy, but it took longer to get here from Leeds than it did to get from Italy to Leeds, including customs clearance. If I'd know this, I wouldn't have paid for the premium service. I have another order on the way from TNT, let's see how THAT goes.

@jmorris I forgot to give you a Yay! when I read your piece. So here's a belated Yay!

@jmorris Working on a full range of items for sale, SMA, 2.92, N and TNC to waveguide transitions, waveguide to waveguide tapered transitions, Cassegrain and Gregorian subreflectors for multiple dishes and frequencies, directional couplers, waveguide and coaxial filters, Edmund Optics dish mounts and focus slides and hopefully some high precision machined dishes for mmWave, parabolic but also axially-displaced ellipse types, lots of feedhorns and lenses. No time to sleep or make Youtube vids!

When I'm designing a Cassegrain antenna for mmWave radio, the main dish is a parabola, but the deep ones from Edmund Optics are very hard to illuminate because they have a focal length to diameter ratio of 0.25, which is WAAAAAY less than most dishes. Solution is to put a hyperboloidal subreflector with its rear focus coincident with the prime focus of the parabola, and the front focus of the hyp is where you put the feedhorn. I made the rear so it can take a very fine adjustment thread

When I create the hyperbolic curve, it is described the usual mathematical way, with just the values of a and b from the standard equation of a vertical hyperbola. Problem is that Fusion CAD describes conic curves in terms of the rho value and the height and width of the tangent intercepts. I guessed there would be a conversion function. HAHAHAHAHA nope. So I sat and did a load of calculus and trig and algebra, resorting to Wolfram Alpha at one point. All sorted, and here is the first reflector

Minor improvements in surface finish on the 122 GHz Cassegrain subreflectors. Using a larger corner-radius end mill. Seven pockets milled, just for the sheer joy of non-symmetry. Still a lot of work to do on pocket finish, deburring/chamfering/radiusing the ribs. My Fusion360 licence doesn't include the 3D debur option. Boo. Investigating whether I can use trace with a sketch path, or design-in some fillets, but that might push the cycle time from "waaay too long" towards "srsly dude?"

@jmorris I have eight of them, but mostly a bit less violence in mine.

@HopelessDemigod There are several 3 element and 4 element 80 metre full sized yagis out there, and a few 3-eles on 160 metres. OH8X used to have a 3-ele on 160 with a 5-ele on 80 stacked above it, but that's only on a 100 METRE tower. Whew! https://ei7gl.blogspot.com/2009/01/mmmma-3-el-yagi-for-160m.html https://www.youtube.com/watch?v=BYhlV_8SFcQ https://www.youtube.com/watch?v=EYUPyBAJzBc

@clacke @drahardja @lispi314 I wrote code in the early 1980s that took full notice that two-digit year fields were a liability and that some folks who were in the datasets were possibly *born in the 1800s* and that the dataset might endure past the end of the 1900s or require forward calculations into the then-distant 2000s. Agreed there were some systems that had so little memory that date compression was needed, but we used binary fields for time, not truncated text dates.

@drahardja Every time some cretin mentioned that Y2K was a hoax, the entire team would respond and suggest that they take their uninformed opinions and go elsewhere. Even 20 years later, we were easily triggered and responded with overwhelming rage. I've almost moved on and now just add them to the idiot pile and treat them with due caution. Two years of our lives wasted on fixing the work of idiots. Marvellous. See also C/C++ coders who didn't understand bounds checking. Idiots everywhere!

@drahardja My team worked for two years on identifying and eliminating shitty applications written by idiot coders who had zero foresight. The business had over 300 apps and a huge shadow IT problem. By the time we hit Y2K, we'd wiped out almost half of the apps and most shadow IT apart from the crappy local databases. Embarrassing the crap out of the hobby coders who thought they knew what they were doing, and holding them accountable for being a significant business risk was mildly satisfying

@HopelessDemigod Heh heh, I have a few of those, including a 50 GHz SpecAn, a load of xxxVNAs, lots of signal gennies up to 26.5 GHz, 6.5 digit Fluke multimeter, , 20 GHz and 8 GHz counters, five power meters rated up to 50 GHz, three GPSDO frequency standards, Rubidium frequency standard, a fancy EMCO EMF meter, digital scope, logic analyzer, variable power supplies up to 100 amps and up to 50 kV, many directional couplers and RF bridges, microwave cavity wavemeters ...

@HopelessDemigod Also function generators, an ultra-low-distortion AF signal generator, a 7 MHz to 4 GHz Agilent Transmitter Tester (basically an FFT specan), oh and a precision buried-zener voltage reference

@HopelessDemigod Oh, and sound pressure level meters, airflow speed measurement (for cooling fans), a set of precision slotted lines for waveguide and coax, sliding shorts, sliding loads and other pre-VNA testgear for measuring impedances and return loss from UHF through to mmWave. I really do have a serious testgear addiction here...

@HopelessDemigod I love the fact that I can machine up a slotted line in my home shop that can make impedance/Smith Chart measurements at the same precision and high GHz frequencies as a $100k+ VNA for less than the cost of the cheapest NanoVNA. In fact, I'll be making a vid about that probably in April

@M0PWX @M0KHR @mw1cgg One benefit of waveguide and stripline construction is that you can make a passive amplifier combiner to run 32 or more power amplifiers in parallel for MOAR PWEOR. 25 years ago there were examples with 272 chips being combined to make 35 WATTS!!! at 60 GHz. Definite Antenna Pr0n in this area of human endeavour

@M0KHR Nope, it has a 1B40 Argon-filled plasma tube with a 0.2 microcurie Cobalt-60 source. When it is in a strong RF field, the Co-60 and bias voltage cause a plasma to form, which shorts out the intermediate cavity between the 1 kW TX and the delicate crystal diode RX cavity. It can take 500+ watts, but only for a microsecond, at about 1000 pulses per second. Problem is that Co-60 half-life is only 5.3 years, so after a decade, it stops working, and by now, nowt left. https://lampes-et-tubes.info/mwtr/1B40.pdf

@M0KHR Uh-huh. Yup. Not a lot of nasties in 0.2 microcuries though, even when it was new, so now only 6 femtocuries left. 0.2 microcuries is about 7 kBq, so by now, the activity is about 2e-15 times that, so well under one decay per second. Although those are mostly 310 keV electrons, the products then decay by emitting gamma rays at 1.2 and 1.3 GeV so it's a bit spicy

Look what followed me home from that ebay. Original early 1950s AN/APX-6 Identification Friend or Foe transponder. These were using during the Castle nuclear tests as well as in many thousands of aircraft, with a base station mounted on the X band radar systems. In the late 1950s, many were bought as war surplus by radio hams and converted to the 1.3 GHz/23 cm band. It makes over a kilowatt from a pulsed disc-seal triode and has a radioactive T/R switch and three explosive Destructors