Originally Posted by Knot Yet
I don't think our little hand-held has the option - we have a Standard Horizon HX750E and the H/M/L refers to watts not channels - having looked at the handbook there doesn't seem to be an option for M1 M2 or P4 - is this something only available on a few radios?
You are correct that the transmit power of your H/H (High, Medium, or Low) is nothing to do with the channels themselves.
Channel 37a is known as M or M1 on most sets, and channel M2 is for some reason known as P4 on Icom sets. They were historically Marina channels in the uk, however the Marinas now have channel 80, which is duplex, so M1 and M2 are used for Yacht Club Safety boats and race control.
To select M1 or M2 (which is how they are programmed) on your Standard Horizon, either go up to Channel 88 and press the up button, or go down from Channel 01. They may look like n1 and n2 - but they will be the ones you want!