David, if I build the QRP-Labs 50 W Amp with the 20M band LPF then plug into the output BNC socket either a 30M or a 40M LPF and then the coax in the Amp BNC socket for 20M or in the 30 or 40 LPF output BNC socket for these bands, I will get a 40M, 30M and 20M Amp on my favourite bands.
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This Amp and LPF filters will just cost US$ 45.50
73 - Pierre - FK8IH
