Topband: Need advice for K3 and RX BC AM

[Jo, YC0LOW]

My Elecraft K3 has no AM filters installed. I tried to RX AM broadcast
stations on MW band but had no success.
I'd be grateful if you could advice me to add it on, or, is there a way to
do it as is, now pse?
I need it as features to check the 160m RX antenna directions in the coming
YB8Y DXpedition (OC-221, GL PI64mh) starts in March 20th. 2012 .

Tnx es 73 de Jo, YC0LOW