Another good example would be actions Brits took in order to protect the fact that Enigma was broken. For example, when Enigma deciphering indicated that there’s warship in a specific area, they would send spotter plane first before attacking it, in order to provide enemy alternative explanation as of how they were discovered. Some operations were aborted entirely for this reason

did they snuck near airbase with a MANPADS?

sorry for being unclear, i forgor a word. what i meant that certain antenna designs would have specific fractional bandwidth, so that just scaling that design to higher frequency makes usable bandwidth wider in kHz terms. in order to get higher fractional bandwidth more complex or bulkier designs would be required, like thicker conductors, added parasitics, something LPDA-shaped, or maybe elaborate matching circuit, all of which cost money. i guess that while resonant amplifiers are a thing, probably bigger limitation would be bandwidth of mixer

i’d also note that antennas, amplifiers and so on have bandwidth that is some % of carrier frequency, depending on design, so just going up in frequency makes bandwidth bigger. getting higher % of bandwidth requires more sophisticated, more expensive, heavier designs. LoRa is much slower, caused by narrowed bandwidth but also because it’s more noise-resistant

but there’s separate category for “broadcast”, so it’s more of point-to-point thing?

what’s fixed service in this context?

Both got much more interesting. Also, don’t underestimate modern encryption

cyanide doesn’t accumulate, it can be broken down in some hours (very small amounts of course). otoh many heavy metals do behave this way, maybe you worked with both at the same time

all metals that bind to sulfur well are to some degree poisonous. these are lead, mercury, thallium, some platinides (in salt form), arsenic, and also copper, but less than others. some metals have other mechanisms of toxicity, like nickel, hexavalent chromium, cadmium, beryllium or barium. some of these accumulate in brain or bones, and some don’t. some are more toxic when inhaled like zinc or chromium

it’s absurdly easily detected and somewhat easily treated today, not in op’s setting

ah yeah the subtle, slow acting poison, the checks notes atropine

all of these work on nervous system which means that they act rapidly. this is worse than useless

https://en.wikipedia.org/wiki/Amanita_phalloides

you also get points for historical accuracy, as it was used as far back as ancient rome

also, how low tech is low tech? Litvinenko was dying for three weeks after polonium poisoning, and radium will have similar effects, first extracted 1898

You can do RC4 on pen and paper, more precisely 256 pieces of paper. There’s also a variant of this cipher that uses deck of cards instead, RC4-52. There’s also another stream cipher that uses deck of cards to store state and it’s called Pontifex/Solitaire. Both have some weaknesses

VIC has way too short key for modern uses, but maybe there’s a way to strenghten it

On related note, i guess that it would be possible to implement modern stream cipher with NLFSR in electromechanical machine, no silicon needed. WW2 era cryptography like this (enigma, M209 etc) were in a way stream ciphers and these require some of least hardware. Key storage and scheduling becomes bigger problem

you don’t see BNC as often because it’s more expensive, bulkier, requires different crimping tool and has a separate soldered pin. but if you need to connect and disconnect things often and quickly, then it’s a good connector. i bet you’ve seen (RP-)SMA a lot instead, but this one is also more expensive than F, has separate pin and is too small to easily make a connector for common 75 ohm cables. reducing diameter would mean higher loss

i keep hearing that F stands for Flimsy. no idea where that came from, unless something is seriously wrong with crimping technique. i guess there’s a tradeoff between CCS or copper cable with durability of pin/center conductor vs bending radius, and some people don’t like how it turns out, while ignoring that it’s cheap and not really designed for multiple disconnections

but yeah, as long as everything is matched good-enough then it’s a cheap way to connect low loss, cheap cable (75 ohm only. otherwise i’m in the N/SMA/BNC camp, UHF connectors are unreasonably obsolete)

The context of the whole thread, though, was end-user, repeated, frequent connections for people who have to be reminded by a manual that the thing needs to be plugged in. Coax is horrible for that.

so you want BNC

power plug with 3 wires or 5 wires (3-phase) could be made safe-ish if there was a button at the very end that connected to a relay or something. but plug like this would be comically long for any practical power

i don’t think you’re supposed to hotplug soldering iron tip. besides it’s a simple thing, isn’t that just two resistors - one for heating element and another for measuring temperature? hard to break that. not sure about how ipod shuffle worked or what precautions were needed. also today USB can deliver power at higher voltages than it used to

Coax has only 2 conductors and it keeps impedance constant, unlike audio jack

There are two immediate problems with round USB. First one is that audio jack carries no power and it’s generally rather harmless for finals or microphone to have some contacts shorted or crossed for time when plug is inserted. USB, let’s even day just 4-pin, carries power and i’m not sure how well would either of devices react to having data bus connected to +5

The other problem is that USB is proper radiofrequency connector, unlike audio jack where anything goes. This means it has to be shielded and impedance has to be some specified value, which in practical terms means that there’s some specific ratio of metal to plastic and shape of conductors that has to be used. Barrel plugs would have way too low impedance and already bulky connector needs extra shielding which makes it even bigger