Wanted info on Fisher tuner FM2400.

You can contact: fisherdoc@aol.com., his name is Al Pugliese and he restores Fisher equipment, he may have a manual for your unit.Good luck.

I am not familar with this particular unit, but in general I would assume the functions are thus:
Fixed Output: Standard input to your Preamp or int. amp.
Variable Output: There should be a knob that adjusts the gain on the signal into your preamp. Somewhat like a volume adjustment.
FM Multipath: Not sure, but assume different elements of a multipath antenna input here. V for vertical and H for horizontal element.
Ground: Ground for antenna
Switched and Unswitched Plugs. These are for accessories to plug in, i.e. cassette, etc. Switched means power at outlet only when tuner is powered on. Unswitched means power at outlet even when tuner is powered off.
These are just guesses, but I think good ones.
Hope this helps and you enjoy your new piece.

Ben