[RTTY] Filters for an ICOM 706

[Ian S. Amos]

Hi All

During the CQ WW RTTY Contest I found the bands very congested, which was 
to expected, however with no filters in my ICOM 706 I was getting clobbered 
by other station and could not print while they were transmitting.  So it 
is time to buy a filter, ICOM has 4 to choose from:
500 hz & 250 hz for RTTY / CW and
1.8khz & 3.3 khz for SSB.

Does anybody have any experience using these or suggestions on the 1 or 2 
that I should pick to solve my problem.  Also can you get them used as they 
are really expensive.

Thanks in advance

Ian
VE3ESH