I Need Help - AI Part 2309

Prompt: I am investigating another design. Using the plug-board approach with the banana jacks would be awkward to configure during band changes. A rotary switch, though difficult to wire, would be a lot less mistake-proof. Using the M1 through M4, C and P1 through P4 designations given above, I calculate that there are 9 different configurations spanning C only to the entire coil from M4 to P4. Do you agree?

A rotary switch is a massive usability upgrade. You are completely right that a plug-board would become tedious during band changes, and a rotary switch makes the operation instantaneous and mistake-proof.

However, on the math, I have to respectfully disagree. While there are 9 physical sections of wire (M4, M3, M2, M1, C, P1, P2, P3, P4), there are only 5 symmetrical configurations.

To maintain that perfectly stationary electrical center we discussed—which is the whole reason for this center-out design—you must always add or remove the M and P sections in matching pairs. If you were to create 9 configurations, you would have to step asymmetrically (e.g., adding M1 without adding P1), which would throw the A1/A2 balanced terminals off-center relative to the primary coil.

Here are the 5 balanced configurations you can achieve:

1. Position 1 (C Only): Taps at the M1/C junction and the C/P1 junction. 2. Position 2 (Add M1 & P1): Taps at the M2/M1 junction and the P1/P2 junction. 3. Position 3 (Add M2 & P2): Taps at the M3/M2 junction and the P2/P3 junction. 4. Position 4 (Add M3 ∓ P3): Taps at the M4/M3 junction and the P3/P4 junction. 5. Position 5 (Full Coil): Taps at the far outer edges of M4 and P4.

## The Rotary Switch Wiring

To wire this elegantly, you need a 2-pole, 5-position (DP5T) rotary switch.

Standard rotary switches are very commonly sold as 2-pole, 6-position (DP6T). If you use one of those, you can simply leave the 6th position blank, or wire it identically to Position 5 as a redundant "Full Coil" stop.

The only downside to the standard rotary switch approach compared to the plug-board is that it leaves the unused outer sections of the coil electrically floating, which brings back the "dead-end" capacitance trap we talked about earlier. However, since you are testing this with your OWON generator and Tektronix scope, you'll be able to see immediately if those hanging ends cause any signal suck-outs on the higher bands.

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Last modified: Monday, 10 Aug 2026