The circuit for the 20 meter filter for the QRP Labs 10W PA is a scaled version of the 7th order Chebyshev filter for 40 meters, using the same filter table. The component values are given in the schematic.
I do not have 150p NPO capacitors in my stock, So I used 100 pF in parallel with 47 pF. I used T50-6 cores for the inductors, again with total 300 mW predicted wire and core losses. The LTSPICE predicted filter response is below.
The filter was assembled on a strip of single sided PCB, as shown in the photo below. Click to enlarge.
The full power filter output into a dummy load is shown below. Click to enlarge. The input voltage is approximately 3.5 Vpp. Frequency is 14.0000 MHz. Output power is 9.9W. Gain is about 25 dB.
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