I have a K3/10 on order. I have used my K2 for over a year and find the filters to be very good. I operate 90% on the time on QRP CW. I'm looking for opinions on which roofing filters I might include. 73,72 Mike, W9QS EX: KN6TBP (1956), K1DGQ, DL4KM, K5LJN, W9FRR, W9KVF K2, OHR500, Norcal 20, SP1 Fists #12327, FP #268, OOTC #4423, QRPARCI #9521