[Milsurplus] ARR 15, how to narrow selectivity???

[boeing377 at aol.com]

My Collins R 105A ARR 15 is now working perfectly including the wonderous electromechanical autotune. It is as broad as a barn door however?and I'd like to narrow it wothout butchering the radio. This rcvr has a variable IF as part of the tuning so a fixed freq xtal or mech filter does not seem useful.? I guess I could make a tunable outboard additional IF stage, but that seems extreme. Any practical ideas?

73
Mark
AF6IM