You are completely right, and that is a classic bench-builder's trap I overlooked. If you wind the permanent primary directly over the center section, it physically traps the secondary windings and tap junctions underneath it. If you build it, seal it, and *then* discover the floating ends are causing resonant suck-outs, you're facing a destructive teardown to fix it.
We can break this chicken-and-egg loop with a temporary test setup. You can sweep the coil using your OWON generator and Tektronix scope right now, before committing to a switch design or winding the final primary.
Here is how to safely mock it up on the bench:
1. Protect the Secondary: Wrap a single layer of masking tape or Kapton tape directly over the center "C" section to temporarily insulate the tap junctions.
2. Wind a Dummy Primary: Take a scrap piece of wire (anything flexible, 5 to 10 turns is plenty) and wrap it over the taped "C" section. Tape the ends down so it holds its shape. This is just to inject the signal.
3. Connect the Test Gear: Hook the OWON function generator to your dummy primary. Connect the Tektronix scope probe across your desired "active" secondary taps (e.g., across M1 and P1).
4. Simulate the Switch with Alligator Clips: Instead of wiring a physical switch, use alligator clips to manually select your asymmetric or symmetric tap points.
5. Sweep and Compare (Floating vs. Shorted): Sweep the frequency generator across Bands 2 through 6. Watch the scope for sudden, sharp voltage drops. Then, take two more alligator clips and physically short the unused outer sections (M2 to M4, P2 to P4). Sweep it again.
If the scope trace looks identical whether the ends are floating or shorted, you have your definitive answer: you do not need a complex shorting switch. You can wire up a simple, single-wafer 9-position rotary switch to simply select the taps, allowing you all the asymmetric flexibility you want without the parasitic nightmare of a 10-wafer assembly.
If the trace cleans up dramatically when you apply the alligator clips, we will know for a fact that the dead ends must be managed, and we can figure out a smarter way to switch it.
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Last modified: Wednesday, 29 Jul 2026