Tuner question What are Gang Stages, What is RF?

Seems the more of these a tuner has the better, 'gang stages' RF's? What exactly are they?
Thanks in advance.
You have a lot of reading to do...gain stages don't mean much as a general term. Find manuals or reviews on older Mac, scotts, fishers, sansui and marantz tuners. Read, read, read...Check out Magnum Dynalab also.
They can all be really good or really bad