Engineering Tool · closed-form · ±10%
Loading Coil
Base-loaded · 7.150 MHz
Required L
20.63µH
Turns N
53.6
Zc exposed
381Ω
Q est
1,032
f-self est
29.3MHz
Wound coil — single-layer air core d 25.0mm · ℓ 75.0mm · N 53.6
Reactance balance — Σ jX at the coil Σ jX = 0 Ω ✓ resonant
| Section | β·ℓ | reactance |
|---|---|---|
| lower | 0.0° | 0 Ω |
| upper | 22.4° | -927 Ω |
| coil | — | +927 Ω |
Accuracy note
±~10%, average-Zc approximation — trim to resonance.
±~10%, average-Zc approximation — trim to resonance.
Method closed-form Cite ARRL / Kraus · Nagaoka Zc 60·[ln(2H/a)−1]