If you look at the tiny low pass filters (toroids plus capacitors) on the circuit board of your uSDX or QDX, that's the size of filtering you need for QRP bandpass filters for 10M or bandstop filters for 20M. ?Both should easily fit in a mint tin. ?Bigger filters are for power handling of RF from QRO transmitters and amps, in use or being used nearby. ?73, Ron, N6YWU
