If your 302 turns of 26 AWG wire are compressed tightly into exactly **4.5 inches**, that means the wire turns are packed beautifully close together (averaging about 67 turns per inch). This extra compression concentrates the magnetic field even more than a standard free-space calculation would predict.
Let's run the final numbers for this 4.5-inch configuration.
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## 1. Final Inductance Metrics (4.5" Length)
With the turns compressed into 4.5 inches on that 0.840-inch PVC pipe, the total inductance climbs to approximately **$265\text{ to }275\,\mu\text{H}$**.
Here is how your physical tap segments distribute that inductance:
| Section | Number of Turns | Cumulative Turns | Estimated Inductance |
| Base Section | 197 turns | 197 | 150 µH |
| Tap 1 to Tap 2 | 40 turns | 237 | 195 µH |
| Tap 2 to Tap 3 | 33 turns | 270 | 230 µH |
| Tap 3 to End | 32 turns | 302 | 270 µH |
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## 2. Why the 4.5" Compression Matters
In RF coil design, compressing the same number of turns into a shorter physical space increases the **Mutual Inductance ($M$)** between adjacent turns.
This layout explains why your Band 1 troubleshooting is yielding distinct results:
* At the full 302 turns ($\sim 270\,\mu\text{H}$), this coil behaves as a heavy loading inductor. It is perfectly optimized to pull a short, 35-foot wire antenna into electrical resonance down at the lowest frequencies of the AM broadcast band ($550 KHz to $800 KHz). * When you switch down to the 197-turn tap ($\sim 150\,\mu\text{H}$), you are dropping the electrical size of the coil by nearly half, which shifts its natural resonant peak right into the higher end of the AM band and the lower shortwave bands.
Now that we have the exact physical geometry of the master coil locked down at 4.5 inches, how does the 30-turn coil overlay look? Where is it positioned along that 4.5-inch span, and what is its wire gauge?
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Last modified: Tuesday, 21 Jul 2026