there is some reason to think this way. also keep in mind that a segment of that anti-americanism was funded by sales of iranian oil. not all of course, but houthis wouldn’t be a thing without it, or large parts of hezbollah, for example. of course what people want and how it shakes down after the bombs drop is different thing entirely, i guess we’ll see, eventually (i assume that decision to strike was already made)
ai is crypto 2 episode 373275
potentially a common one, but we’ll only know after password leak from somewhere
i was thinking more like, thin external plastic shell and empty cells inside, perhaps with another thin plastic shell on inside, and internal metal shell (on plastic support?) fitting in snugly, for mechanical stability, idk 3dprinting
keeping leads short and nonmagnetic (dramatic reduction in skin layer depth) would be a good thing because of losses, but the longest object in capacitor would be just capacitor plates, and either way in wavelength terms it’s rather small. more precisely you can model it as open transmission line stub with some weird and low impedance, but it’s so small that you don’t have to. you can also make capacitor shorter and wider, or even add more layers like how vacuum variables are made. in nesting design you can get taper effect just by making inner layers longer
Found a piece about RFI and baluns, http://audiosystemsgroup.com/RFI-Ham.pdf multiple turns on ferrite aren’t really an option for VHF and up, ended up ordering extra beads (non-split)
The dielectric between the plates in this case is 0.4mm of ABS plastics (+ a bit of air in the 3d print layer lines).
in terms of losses, PP or PE is a bit better than ABS, teflon or FEP is a bit better than PP, but air is superior to either (this is part of the reason why foam coax is a thing). not sure which ones are printable, or whether it’s practical at this size, but try to introduce as many voids as possible (perhaps requires larger thickness of dielectric). it doesn’t matter much in your case, because of low power (warping of plastic because of excessive heat is probably not a problem). if your coax has solid dielectric, then by introducing enough air in 3d-print your variable might become less lossy than that
The Capacitors allows my 80cm diameter loop to tune from 20Mhz to 37Mhz. Sweeping the whole range is a bit slow due to the low RPM of the motor and takes about 6min. But that is kinda nice when fine adjusting to a frequency.
you have probably noticed that position vs resonant frequency relationship is rather nonlinear. you can get higher sweep speeds at lower end without losing much accuracy at higher end by tapering end of side plates into a triangle shape (it will get longer overall). it doesn’t matter much in your case, because it’s all approx monoband, but if you want to go multiband with this, then it’ll be a nice enhancement. similar effect happens when air variable capacitors have moving plates shaped in such a way that one end is longer than the other, and external edge has shape roughly like a section of logarithmic spiral. precise movement of variables like this is done by use of worm drive with large wheel
I am not sure what is causing this, but i assume it could be due to increase of dielectric losses in the capacitor getting bigger when more of the plates overlap because then the electric field has to flow thru a bigger area of dielectric, increasing the potential for losses.
loss tangent of dielectric is material property, that is ratio of equivalent loss resistance to capacitance should remain constant at given frequency. so i guess that losses should remain roughly the same, if dielectric is to blame, but at any rate lossy capacitor should make bandwidth broader and SWR lower. my guess would be that it’s a matter of coupling loop becoming wrong-sized or wrong-positioned at some point with change in frequency (try moving it up or down? there’s gotta be some optimum position for your entire range of interest)
it’s crazy how people memoryholed that (and japan doing the same, and a handful of other countries). or how until 2022 war norway wasn’t really thought of as petrostate by people who didn’t pay attention. or how ten years ago, if you said that putin bombed apartments to wage war on chechenya to win elections all to pardon yeltsin, people would think that you’re a crackpot
no there’s also racist twitter
i’ve collided with an article* https://harshanu.space/en/tech/ccc-vs-gcc/
you might be wondering why it doesn’t highlight that it fails to compile linux kernel, or why it states that using pieces of gcc where vibecc fails is “fair”, or why it neglects to say that failing linker means it’s not useful in any way, or why just relying on “no errors” isn’t enough when it’s already known that vibecc will happily eat invalid c. it’s explained by:
Disclaimer
Part of this work was assisted by AI. The Python scripts used to generate benchmark results and graphs were written with AI assistance. The benchmark design, test execution, analysis and writing were done by a human with AI helping where needed.
even with all this slant, by their own vibecoded benchmark, vibecc is still complete dogshit with sqlite compiled with it being slower up to 150000x times in some cases
yawn, i diagnose that LWer with weeb. this is something happening across entire industrialized world, causes being high performance mechanization of agriculture, old people being stubborn in regards to moving, lack of specialized work in countryside and couple of other factors. germany has patched their hospice staff shortage (not sure how effectively) with migrants, but japanese are way too racist for that. same thing happens in moldova, but you never hear sob stories about retired moldovans because they’re broke and nobody cares, while moldovan govt can’t really do much about it (because broke) to degree that it has not just economic and demographic, but even strategic effects. whole lotta drs strangelove in there
should have glued it in place smh
Skin depth is larger in aluminum but not enough to balance out its lower conductivity, copper is better material taking all into account, in practice both are good. If opposite was true we’d use lead or zinc for conductors. There are satellite microwave parts made out of aluminium (low weight) coated sequentially with zinc (bonding layer), copper (better conductivity), thin layer of silver (even better conductivity) and then gold (actually not thick enough to contribute, this one is for corrosion protection)
also ignoring that natanz was actually effectively airgapped, and was knowingly infected by another country’s contractor’s usb stick, working on behalf of dutch intelligence service
the thing with using aluminum tape is that you can get away with very small thickness, because current flows only in top tens of micrometers depending on band. you can just roll up, say, 5cm wide, 0.5mm thick aluminum tape and have riveted/brazed/spot welded short length of 2mm thick bar to the ends for connecting capacitor. the problem is with mechanical stability of this setup, which is why you see pipes and thicker bars, bicycle rims etc, and here you would need some kind of horizontal bars for loop to more or less keep shape
with braid you get a lot of contacts between wires, and i’m not sure that resistance of them would be low unless tire is fully inflated. keep in mind that copper in contact with some grades of rubber develops copper sulfide film. maybe you can put short U-turn within loop at end opposite of capacitor and have adjustable shorting bar there. adjustable capacitor is more common by far, because if you can adjust it widely enough, you can get to different bands
if you’re going for portable operation, wire dipole is probably the better way to go. cheaper, lighter, more efficient, you can roll it up and fit in your pocket. if you’re operating out of a car, you don’t need to fold magloop just lay it flat in the trunk
i’d expect shield to fray and core to bend with arrangement like this. if you just slide piece of pipe (can be rectangular, or U-shaped) it should be more durable. you’d be surprised at voltages developing there, even with 4W online calculators suggest something in 1kV range. 100W is over 5kV (voltage scales as square root of power)
btw if you don’t need it collapsible, consider using bicycle rim as loop, or some kind of wide aluminum tape, as it has much higher equivalent diameter than coax (less losses)
i don’t give a shit about sam harris. if iranians were broadly fine with theocracy, there wouldn’t be 30k+ dead protesters last month, or major protests every year for a decade. like every other country on earth, you can expect that iran secularizes, except that apostasy or conversion is capital offense, or any significant dissent for that matter, so any survey unaffected by self-censorship would be hard to conduct