Is it possible for an AM radio to use 75 Mhz on channel 90?
Yes they do make a 75mhz AM . And you still need to be aware of other people using 75mhz FM on your same channel.
That JR 75mhz AM is the radio system that came with the Mayhem ST.
I have a Futaba Magnum Sport that is on that frequency. I was hoping I could use the receiver with my JR XS3 but I don't think that will work.
nope, you can't use a am receiver with a FM radio.