In my opinion the 250hz filter was a good option to purchase. I have mine switch in at 350Hz. John KK9A Tom nineback wrote: Tue Mar 14 11:47:11 EDT 2017 OOPS. I looked a the build sheet again and see that I did get the 250 filter. I don't remember ordering it but I did. I also took off the top cover and the filter is properly annotated. 73, Tom - KQ5S