Hi Enrico,
I'm very interested in your work. Unfortunately your pictures did not make it through. Can you link through dropbox, or maybe try again?
Do you have access to a VNA (like a nanoVNA)? It would be interesting to see a S21 (or S11 into a 50 Ohm load) through the BPF segment. A entire HF sweep would be ideal, one or each of the band selections. I might do it myself next time I have the rig open.?
What is your theory? Without the electrolytic cap bypassing RF when the Filter line is not pulled low, that the BPFs were "self activating" through RF, and therefore multiple BPFs were "open"? Seems plausible, if that is your thinking ...
Kind regards and thanks,
Mat, N8TW
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-Mat Breton, N8TW
Mat Breton N8TW