What is the differences in the 27, 40, 50 or 75 MHZ in a radio and which one is right for me ore can you have all three at times with the same controller.
40 and 50 mhz is not legal to use according to FCC. 27 Mhz has only 6 channels. 75 mhz has 30 channels. Both 27 & 75 mhz come in AM or FM.
Theoretically, AM and FM of the same channel can be run without together but why risk the chance of glitching? At the track where I run, they don't care whether it's AM or FM ... can't have the same channels. It's a good practice to go by.
Mhz stands for megahertz. I've seen a few 40mhz for sale on eBay. It's mostly used in europe and asia. Canada has them also. FCC has them reserved for something else here in the states.