The bands are crowned with CW signals and isolating the one you want to hear is difficult. Many Radios do not have built in filters for this mode and we have to make do with the stock SSB filter. Often you can buy a suitable plug in filter but expect to pay a three figure price for it. If you change the radio at a later date then you start again looking for another expensive filter. the answer? Well this is a standalone filter that connects to the headphone/speaker out socket of you radio and allows a external speaker to be plugged into it . The filter offers an amazing reduction in noise and a major improvment in selectivity, you will be suprised the difference such a low cost option can make and of course it can be used with other radios you buy in the future.
Its technically called an adjustable low pass filter , 90% of interference is above the CW tone frequency so in practice I find its performance seems as good as my stock 500Hz filter in the ft818 I have. Of course this filter is working on AF signals so a very strong signal in the receivers AGC passband can still cause some degrading of the wanted signal but I find that I still prefer the sound though this filter than via the 500Hz filter from Yaesu. Have a listen to the audio on my video for evidence of the difference this filter can make in the real world and make your own mind up! the video is here SCAF Test
Audio In /Out and power 12v DC sockets on the back.