[Collins] wider audio for 51J4?

[Eugene Hertz]

Hello all,

In a discussion with a friend, we were talking about the narrow 6kc filter of the 51J4 and we were wondering can this be replaced with some simple rc filter (or otherwise) for better AM audio bandwidth?  Can 12kc be attained? Whats the most (at the sacrifice of selectivity)? 

Anyone have (or can point me to) a circuit diagram for a nice wide output? 

thanks!
Eugene
PS Someone out there in collins land must have some bad J4 filters,no?