[Elecraft] Adding Filters to K3

[Frank]

I have an Elecraft K3 with a subreceiver with 3 of the 5 slots filled 
with filters.  For SSB both the main and sub receivers have a 2.8 khz. 
filter.  I have one 1.8 khz. filter I would like to add to the main 
receiver.  Can I add this filter to the main receiver and leave the 
corresponding sub receiver slot vacant?  I understand only the main 
receiver would benefit from the 1.8 khz filter and I am fine with that.  
The sub receiver would still use the 2.8 khz. filter I assume.  Any 
thoughts would be appreciated.

Thanks,

Frank

K6FW