ok so i finally upgraded from tech to general last month and im trying to figure out the 40m band. i know generals get more privileges but i keep seeing different charts online and some of them seem to contradict each other or at least i think they do. like the FCC allocation says one thing and then the ARRL band plan says something slightly different and i dont know which one actually matters legally.

also whats the deal with band edges, my elmer told me to stay away from the edges but didnt really explain why. is it just interference or is there some rule about it. sorry if this is a dumb question i just dont want to accidentally transmit somewhere i shouldnt be

not a dumb question at all, honestly the band plan stuff confused me for a while too. so the short version is the FCC Part 97 allocation is the actual legal limit — that's what you have to follow. the ARRL band plan is more of a gentlemens agreement about where different modes tend to hang out, like SSB up here, digital down there, that kind of thing. you wont get your license revoked for operating SSB in the wrong chunk of the band plan but you might annoy people.

for 40m as a general you can do SSB from 7.175 to 7.300 MHz. the lower chunk from 7.025 to 7.125 is for CW and digital. the band edge thing your elmer mentioned — the reason you stay off the very edge is that your signal has sidebands and if youre running SSB on 7.300 you're actually transmitting a little bit above that depending on your filter and audio. so you could technically be out of band even if your dial says 7.300. most people just stay a few kHz inside to be safe.

yeah what he said about the sidebands is the big thing. i learned this the hard way when i first got on HF, was sitting right on 7.300 calling CQ and somebody told me i was splashing above the band edge. your typical USB signal can be 3kHz wide so if your carrier is at 7.300 your audio could be going up to like 7.303 which is out of the amateur allocation entirely. just keep a few kHz of margin and youre fine, its not worth sweating over too much once you get the hang of it