Only if you operate CW :-) INRAD filters for the TS520, and other Kenwood radios, are not only available, but also superior to the original filters, by and large. http://www.qth.com/inrad/ <http://www.qth.com/inrad/>Chris 2009年11月24日 Richard Knoppow <1oldlens1 at ix.netcom.com> > Its it worth installing the CW filter for the TS-520S. > If so, are they available? >>>