Thoughts : on 40/80 BPF - 12 v relay triple pole . 40 M off ? - 80 M on . Relay adds extra capacitance in for 80 m across C2 / C4 / C6 about 600pf . I am not sure how much stray capacitance of the relay might contribute to the filter . mount the relay on a small perf board next to the BPF . Just an idea.?
