westfw:
the regulations around RF emissions are ... obscure. The devices from the manufacturer, carefully designed, tested, and probably licensed from the FCC ... perfectly legal.
Cobbling together home-brew circuitry that emits "something" at the same frequency: not legal. (Possibly interfering with maritime radio is a extra badness...) Using wildlife tracking gadgets for purposes other than wildlife tracking - also illegal. Ordering Pizza via Ham Radio - illegal. Etc.
Ordering Pizza via Ham Radio
but it works 
73!