Hi I am new here and looking to get a Variax JTV-89. As I've been browsing I've come across different models such as JTV-89F, or JTV-89US or even a a JTV-69S. I know the 69 is different than the 89, but what is the difference between an "F", "US", "S" and just a regular JTV-89 with no extra letters?
Thanks!