Hola Andres,
I had the same problem when I started with Electric pattern aircraft. I don't know anything about rx of Futaba, but when I testd the dual convertion rx of Graupner/JR the problems disappeared. Aside from this, I take the antenna outside like Neo02 and take also the rx far of the regulator and batteries.
What's your plane?,
Regards, Saludos.
Joan