Stop Blaming Your Coax — The Real Power Killer Is Your “Wideband” EFHW

Many operators blame their feedline when signal reports drop, but coax loss is rarely the real culprit. The true watt-eater in most multiband setups is the antenna and matching system — especially the “wideband” EFHW that claims 80–10 m coverage through a single 49:1 transformer. Above 20 m, its efficiency and pattern stability collapse for very real physical reasons.

TL;DR

• Coax loss is rarely the problem — most dB vanish in the matching unit and return path of EFHW systems.
• Antennas around 100–200 Ω (OCF dipoles, delta/skyloops, verticals on 4:1 or 2:1) are inherently easier to match and stay cooler on 15 m / 10 m.
• EFHWs shine only when kept narrow (single- or dual-band). “Wideband” 80–10 m boxes burn power in ferrite and copper once you climb above 20 m.

Where the Power Really Goes

An EFHW feedpoint sits in the 2–4 kΩ zone. That demands a 49:1–64:1 ratio, which is a difficult broadband compromise. OCF dipoles, loops, or verticals fed near 100–200 Ω instead require ratios like 2:1 or 4:1 — much gentler to the ferrite and easier to keep linear. None of these systems are truly balanced, so they all need a good autotransformers in practice. With a proper counterpoise and a well-placed current choke, efficiency rises across all of them. The only one that stays temperamental is the 49:1 EFHW, particularly above 20 m.

The Return Path You Didn’t Plan For

Every end-fed antenna needs an equal and opposite return current. Without a proper counterpoise, the coax shield becomes that return path, radiating, distorting your pattern, and soaking up heat. On the higher bands the problem grows worse, since the coax becomes resonant at fractional wavelengths. Adding a 1:1 choke roughly 0.05 λ from the feedpoint greatly helps — but a well-designed counterpoise does even more.

Transformer Efficiency at a Glance

Above 20 m, the losses in the matching box and common-mode path often exceed the coax’s own matched loss.

Why “Wideband” EFHWs Fail on 15 m & 10 m

• Impedance drift: The same wire that’s ½ λ on 40 m becomes 1.5–2 λ on 15/10 m, throwing its feedpoint impedance far off the transformer’s design ratio.
• Parasitics matter more: Leakage inductance and stray capacitance dominate at high frequencies; adding a ~100 pF C0G capacitor merely masks the imbalance and can introduce extra loss — though it often presents a deceptively “nice” feedpoint impedance that fools the operator.
• Resonant return path: The coax or ground path starts to act as part of the antenna system, shifting SWR and raising stray return currents resulting in more loss.
• Pattern chaos: A 2 λ wire splits into multiple lobes and nulls, creating “hot” and “dead” directions on the map.
• Stress inversion: High voltage dominates at low bands; high current at upper bands. Both increase loss when the transformer runs close to its limits.

Real-World Efficiency Comparison

Those “missing dB” often show up as heat in the box or noise on the coax. The operator’s SWR meter still reads fine, but the RF isn’t making it to the ionosphere.

Why 2:1 and 4:1 Systems Stay Calmer

None of these feed systems are truly balanced; they all need an autotransformer. What helps is moderate impedance ratios, which keep voltage and current manageable. When combined with a real counterpoise and a good choke, they maintain low loss and predictable behavior across multiple bands. The 49:1 remains the outlier — efficient up to 20 m, but increasingly unforgiving above that.

How to Make EFHWs Honest

• Keep them single- or dual-band (e.g. 160/80, 80/40 40/20) so the end impedance stays near the transformer’s optimum.
  
• Skip “compensation caps” as band-aids — they often mask problems instead of curing them.
• Add a dedicated counterpoise and a 1:1 choke about 0.05 λ from the box to reduce stray return currents that only add to the loss.
• If the box warms up at power, the lost watts are in ferrite and copper — not in the coax.

9:1 Random Wires — The Same Lesson

Even a 9:1 UNUN can be efficient if used correctly. But when the tuner sits in the shack, the coax between UNUN and tuner operates at high SWR, wasting power as heat. Move the tuner to the feedpoint and give it real radials — the improvement is immediate.

Bottom Line

• Above 20 m, “wideband” EFHWs lose more dB in ferrite and copper than in coax.
• 2:1 / 4:1 systems behave better simply because they operate in a friendlier impedance range.
• Provide counterpoises and chokes — the simplest path to reclaim lost watts.

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