I never could quite figure out exactly what a "Q Multiplier" does.

There is a Heathkit model QF-1 Q Multiplier on ebay and that got me to
wondering.

I know what "Q" is regarding inductors and capacitors ("Quality factor",
reactance divided by resistance) but I don't know exactly what a Q
Multiplier does or how it connects (I assume it connects to a receiver but
am not even sure about that). Obviously it "multiplies the Q" but of what
component(s) or stage(s)?

Any of you boat anchor enthusiasts know about this?