ok so i just upgraded to general and i'm trying to figure out 40 meters but the band plan stuff is kind of confusing me. like i know there's a difference between what the FCC actually allocates and what the band plan says but i dont really understand how that works in practice. my friend told me to stay away from 7.125 to 7.175 or something like that because of some international thing but i cant find a clear answer on why. also i keep seeing people say dont operate right at the band edge but nobody explains what bad actually happens if you do. is it just an etiquette thing or can you actually get in trouble

yeah so the short version is the FCC allocates General class phone privileges on 40m starting at 7.225 MHz up to 7.300, and then there's CW/data lower down. the 7.125-7.175 range your friend mentioned is a shared international thing where other countries have primary allocations and you can end up causing or receiving interference from stations in other ITU regions, its not illegal exactly but its a mess. the band plan on top of that is just a gentleman's agreement basically, ARRL puts it out and most people follow it but the FCC doesn't enforce it directly.

as for band edges, the issue is your signal has sidebands, so if you're on USB and you tune to exactly 7.300 you're actually putting energy above that. the FCC looks at your occupied bandwidth not just your carrier frequency so you can technically be cited for operating out of band even if your dial reads 7.300. most people just stay a few kHz inside to be safe, like 7.295 or so for an upper limit.

i was confused about the same thing when i upgraded honestly. what helped me was just downloading the ARRL band plan pdf and keeping it open while i was getting started. took me a while to realize the band plan and the actual regulations are two different documents lol. i still kind of just avoid anything that feels like it's near the edge tbh, easier than trying to do the math on SSB bandwidth in my head