if you have an antenna with impedance of, say, 200 ohms, then you need to match it to transmitter impedance of 50 ohms, or else most of power output from transmitter would be bounced back and will damage output stage of amplifier. because on receive currents are tiny, you can wing it by just using it without any match and connecting it directly

transformers are not the only way to do this, and some other circuits can be used instead. if you take a transformer with 1:2 winding ratio, then if on one side current is 1 and voltage is 1, then on the other current will be 0.5 and voltage 2, which means that impedance increases 4x. in EFHW, it’s 1:7 winding ratio and impedance ratio is 49x, which works for end-feeding a half-wave dipole, just as expected (from 50 ohm to ~2500 ohm). that transformer is a limitation on power usable in this antenna and main reason to use this type of antenna is mechanical

most importantly, transformers work nicely only if you have real impedances, so your antenna has to be resonant anyway. l- or pi-network tuner will also handle complex impedances so doublet or random wire will work nicely with it, as long as you can accept weight and losses in tuner

how compact and what do you want to do with it? if it’s for receive only, the most compact you can get is ferrite rod antenna, but it’s very different from usual wire antennas used for transmission. if using wire antennas, random wire would be fine

it depends on whether you want to transmit or not. if not, you can just use random wire antenna

random wire antenna is exactly what it says on the tin - length of random wire strung up as high as you can, as long as you can make it work. the other part is ground, where you might want to lay some lengths of wire and connect them in a single point, to act as radio ground. it won’t have right impedance (probably 50 ohm) but for receive, this is ok - it’ll be probably usable, and you can amplify signal without penalty because amplifier noise will be much smaller than atmospheric noise already present. the amount of power bouncing around is tiny and can’t damage anything

if you want to transmit, you’ll need more elaborate antenna. what you can use depends on whether do you have a tuner like neidu3 describes or not. if you do, common choice is doublet which is a specific length of wire connected to tuner with a 400-ohm parallel line. if you don’t, common choice is halfwave dipole which is halfwave long, and put as high as you can get, either vertical or horizontal, but for practical reasons mostly horizontal, or monopole, that is quarterwave long, but requires lots of wire on ground to act as radio ground. you can make them shorter using coils, but this makes bandwidth narrower. in any case, it’ll be need to be tuned to your band in question, for which you need a tool like nanoVNA. tuner also narrows your bandwidth, but you can retune it so it doesn’t matter that much. (it’c called instantaneous bandwidth)

is there something you don’t understand? it doesn’t fucking matter what russians claim to have tested, you as nato resident are protected by nato’s ability to evaporate moscow and moscow residents survival instinct, meaning that they won’t start shit if they want to remain not evaporated. it works in any number of ways between any number of nuclear states, and can’t be undone

nothing. safety of people in nato is guaranteed by a several of icbms somewhere in wyoming or in some submarine with putin’s name on them. self-preservation is a mighty powerful instinct, and it worked for entire cold war. will easily work for a couple of decades more

I don’t want to be remembered at all. If I’m being remembered it means I’m dead.

Yuri Orlow in Lord of War (2005)

aluminum bars, they won’t be able to work it into things like with iron. even if they do, they can’t make more

i’m gonna infect you with covid stay away

deleted by creator

there’s writefreely, a service which is a part of fediverse which might be what you’re loking for

dan olson/folding ideas

otoh E contains active warzone and D two of them or more, depending on how you count

in many flats even recently built you don’t get three-phase power, just single phase, but building divides single three-phase supply into three groups of single phase circuits like you say (do you really need 20kW in residential flat? one that doesn’t use EV charger, built in 90s-10s?) i guess it depends on country also. separate houses tend to get three phase connection where i live

floating neutral will also be a problem in american-type two-phase installation, might be even worse (more frequent) on account of large number of lightly maintained transformers used (why on gods green earth there’s few-kV medium voltage line going down every street, americans make it make sense)

Today many of switching mode power supplies accept anywhere between 100-250V

bases of pins are insulated, like in type C/E/F

you don’t have to have three phase circuit to be affected by floating neutral in three-phase substation upstream. in some places in us there are 208v interphase three-phase circuits, which give 120v phase to neutral, which is distributed as a pair of wires as single-phase circuit. this is also normal way to deliver single-phase power in europe, as it’s most efficient use of conductor. (from 400v three-phase circuits) in case more power is needed than single-phase circuit can deliver, three-phase circuit is installed

if there’s switch on device, it’s 2p1t meaning both phase and neutral are switched. if it’s permanent, non-pluggable circuit, like lightning, it’s okay if only phase is switched (neutral is connected permanently)

it’s a bad practice to design appliance in such a way to assume that neutral will have low voltage, because in case of neutral failure in three-phase circuit you can get full voltage there, and there can be a couple of volts difference (sometimes more) between neutral and ground even in normal circumstances

it’s better to cut off both live and neutral at the same time anyway, especially if there’s no standard which is which. also, as device designer you don’t know if it’ll be used on a circuit that has neutral and phase where you think it’ll go or not. (ie british appliance used on unpolarized circuit, like type F. adapters exist)

Type E/F carries 16A/230V, and nowadays there are shutters included which only allow two pins to be inserted at once, not one but not the other. There’s no standard as of which pin should be L1 and neutral anyway, nor it should matter, and fuses in british plugs are to accommodate ring circuits, which were introduced as a result of copper shortages (ie decades of tech debt)

Or you could just use thicker wires like everyone else, or drop the use of ring mains, which is the actual reason why fuses in plugs were introduced. The reason why this was done was post-WW2 copper shortage. In other countries you’ll see more likely star type circuit