I need (really NEED) to get a cw filter for my FT-840. Yaesu makes a 500Hz 8-pole filter. I also see that INRAD makes a 250 and 500 Hz 8-pole filter for the FT-840. How do the INRAD filters stand up against Yaesu's? Has anyone seen a Collins for this radio? Any help would be appreciated. Mark, AB7MP