Before revision: The tuned RF stage with optional RF amplifier provides some initial selectivity; it is necessary to suppress the image frequency (see below) , and may also serve to prevent strong out-of-passband signals from saturating the initial amplifier.
After revision: The tuned RF stage with optional RF amplifier provides some initial selectivity; it is necessary to suppress the image frequency , and may also serve to prevent strong out-of-passband signals from saturating the initial amplifier.