Field Note: FMF-01 Pilot Run

A NanoVNA-H4 measured S21 from 50 to 150 MHz at 401 points with a 1 kHz displayed bandwidth, following a two-port C3 calibration at the cable reference planes. The FMF-01 is a passive Nooelec Distill:FM Barebones filter whose exposed PCB is silk-screened Flamingo FM.

At 98 MHz, measured insertion-loss magnitudes were 33.17 dB forward and 32.97 dB reverse, showing reconnection differences of 0.03 dB and 0.00 dB. The corrected S21 minimum searches found -35.52 dB at 94.500 MHz forward and -34.45 dB at 95.000 MHz reverse.

The sparse marker readings show a strong FM-band stop region, along with a visible transition affecting the lower VHF airband. The THRU control was -0.00 dB initially and 0.00 dB after the final search check at 100 MHz.

The VNA controls and reconnection repeatability make this bounded result intelligible without establishing a whole-band specification. The evidence is limited to discrete marker readings and focused search photographs; no Touchstone export was collected.

The pilot supports labeled-forward, receive-only A-B-A trials with receiver bias-T disabled. A broader calibrated sweep and raw trace export remain appropriate before continuous-response or whole-band specification claims.

The pilot does not establish the current greater-than-40 dB statement, nor does it establish a defect, fraud, nonreciprocity, or anomaly. The operational status remains focused on controlled measurement and repeatability checks.

Wonder survives when the evidence is allowed to keep its edges. A result can be useful without pretending to be more complete than it is; apparently unusual behavior becomes intelligible when the trace, the reference plane, and the limit are named together. The factual anchor for this reflection will be linked to the Scientific Public Ledger entry after owner approval.