I realized my 3 switchable filters aren't enough for all HF bands.

E.g. 1.8 MHz has also a 2nd harmonic not filtered by LPF1, while 7 MHz also has a 2nd harmonic not filtered by LPF2.
Therefore I suppose I need 4 or 5 filters:

• LPF1 cut off at 2.2 MHz for 1.8 MHz 
• LPF2 cut off at 5.6 MHz for 3.5 and 5.3 MHz
• LPF3 cut of at 11 MHz for 7 and 10 MHz
• LPF4 cut off at  23 MHz for 14, 18 and 21 MHz    
• LPF5 cut off at 32 MHz for 24.9 and 28 MHz