ok so I just upgraded from tech to general last month and im trying to figure out the 40m band. I keep seeing different charts online and they dont all agree with each other. like some say phone starts at 7.175 and others say 7.200 and I dont want to accidentally transmit somewhere im not supposed to be.

also whats the deal with band edges, someone at the club meeting said to stay away from them but didnt really explain why. is it just interference or is there an actual rule about it

The confusion is probably because youre seeing both the US allocations and the IARU band plan mixed together. For US General class on 40m, phone privileges start at 7.175 MHz up to 7.300 MHz. Anything below 7.175 is CW/data territory for generals, and Extra class guys can work phone down to 7.125.

The band edge thing isnt a hard rule exactly but its practical. Your signal has sidebands that extend a few kHz depending on how wide your audio is, so if youre sitting right at 7.300 on USB your actual transmitted signal could be spilling outside the band which is an FCC no-no. Most people just stay a few kHz inside the edge to be safe. 7.295 or so is usually a fine upper limit without overthinking it. The lower edge on the phone portion is the same idea, just give yourself a little room.

yeah and on top of that 40m gets complicated because of the shortwave broadcast stations that come in at night, especially from like 7.200 up. you'll sometimes find the bottom of the phone segment gets pretty crowded because guys are trying to avoid the broadcasters. just something to be aware of when youre picking a frequency