ok so ive been licensed for about 3 months now and i keep getting confused about the 40m band. i know generals have phone privileges starting at 7.175 but i keep seeing people operating like way down around 7.150 or even lower and i dont know if theyre extra class or if im missing something about the band plan. also whats the deal with band edges, someone at the club told me to never operate right on the edge but didnt really explain why. is 7.175 actually safe to use or should i stay a bit above that to be safe? my rig shows the frequency but i wonder if its perfectly calibrated too

yeah this trips up a lot of new generals. so the fcc allocation for general phone on 40m starts at 7.175 MHz, but here in the US the whole 40m band only goes up to 7.300. thing is your signal has a certain bandwidth — if youre doing SSB youre looking at maybe 2.8 kHz or so of occupied bandwidth. if you tune your rig to 7.175 and youre on LSB, your signal actually extends a couple kHz below that carrier frequency. so technically part of your signal could be bleeding into the extra-only portion below 7.175. thats why guys say stay a bit above the edge, like 7.178 or so gives you some breathing room. most rigs are close enough on calibration that it wont matter much but old radios can be off a little. the people you heard down around 7.150 are probably extra class, or they could be DX stations since the band plan is different outside the US and 7.125-7.175 is wide open in other countries.

the DX thing is a big one honestly, i spent forever wondering why i kept hearing european stations down around 7.130 until someone explained that iaru regions have totally different splits. they dont have the same subband structure we do so they just operate wherever. was kind of a lightbulb moment for me. anyway yeah stay off the actual edge, ive heard of guys getting a courtesy notice from the fcc over stuff like that, probably rare but not worth it