EFHW16080 Inverted L — Technical Overview
Updated: 2025-08-19 — Technical overview validated for EFHW16080 inverted‑L geometry, transformer class, and power envelopes.
EFHW16080 — Technical Overview
The EFHW16080 is a high‑power, dual‑band end‑fed half‑wave for 160 m and 80 m. It’s engineered specifically for inverted‑L deployments to deliver reliable resonance on both bands without traps, loading coils, or SWR‑flattening capacitors — maximizing efficiency and stability at legal‑limit power.
Includes high‑performance 68:1 transformer, XLPE‑sheathed wire (~82 m), stainless hardware, and weather‑proof enclosure. Add a quality high‑CMR choke ~8 m from the feedpoint or at shack entry and you’re on the air.
Specs at a Glance
| Spec | Details |
|---|---|
| Type | End‑Fed Half‑Wave (EFHW), dual‑band 160/80 m |
| Power Rating | 4 kW ICAS, 2 kW CCS, 1.5 kW continuous FT8/FT4 (≤ 2.5:1 VSWR) |
| Matching | 68:1 UNUN, ~3–4 kΩ to 50 Ω, < 0.2 dB insertion loss |
| Radiator Wire | ~82 m tinned‑copper, 2 mm stranded, XLPE sheath (UV‑resistant) |
| Enclosure | Rugged polycarbonate, IP64; pro PL connector (weather‑sealed when dressed) |
| Hardware | RVS316 stainless: carabiner, grips, duplex clamp, thimble; ceramic egg insulator |
| Reference Deployment | Inverted‑L: ~18–20 m vertical + remainder horizontal (high/clear) |
| Choking | High‑CMR choke ~8 m from feedpoint or at shack entry; optional ground stake |
| Weight | ~650 g (transformer assembly, excl. deployed wire) |
For all bolts, screws, and electrical interfaces, apply AL‑1100 aluminum paste during assembly to prevent galvanic corrosion and keep contact resistance low in outdoor exposure.
How often? One thorough application at installation is typically sufficient. In harsh coastal or polluted environments, re‑apply every 2–3 years during visual inspection, or sooner if you open/re‑torque joints.
Operating Bands & Angles
| Band | Typical Behavior | Indicative Angles* |
|---|---|---|
| 160 m | Low‑band DX + NVIS mix; vertical leg drives low angles | ~18–28° (height dependent) |
| 80 m | Regional NVIS + mid‑angle DX; broader sweet spot with L‑shape | ~22–35° (height dependent) |
*Angles are indicative for inverted‑L installs with sound choking and clear surroundings.
Electrical Design
- Matching: Integrated 68:1 UNUN transforms ~3–4 kΩ EFHW feedpoint to 50 Ω with < 0.2 dB insertion loss.
- No “SWR‑flattener” parts: No parallel caps or loading coils — avoids efficiency loss, detuning under power, and low‑band hotspots.
- Dual‑band focus: Targeting only 160 & 80 m keeps core heating and loss controlled at high power vs broadband EFHWs.
An external tuner is recommended: 160 m is narrowband; 80 m cannot span the full allocation with one dip. Center your preferred segment < 2:1.
Mechanical & Build
- Radiator wire: ~82 m hard‑drawn tinned‑copper, 2 mm stranded, XLPE sheath.
- Transformer: PTFE windings on high‑performance ferrite for low loss and thermal stability.
- Enclosure: Polycarbonate IP64; connector: professional PL, weather‑sealed when dressed.
- Hardware: RVS316 stainless (carabiner, grips, clamp, thimble, ceramic egg insulator).
- Weight: ~650 g (transformer only).
Power Handling
- ≤ 2.5:1 VSWR: 4000 W ICAS, 2000 W CCS, 1500 W FT8/FT4 (continuous duty).
- > 2.5:1 VSWR: De‑rate sensibly — < 1500 W PEP (> 3:1), < 1000 W PEP (> 5:1).
Installation & Geometry
- Reference layout: Inverted‑L (~18–20 m vertical, remainder horizontal). Keep the horizontal run high and clear.
- Mast height: 15 m works; 20 m improves 160 m DX takeoff angles.
- Clearance: Keep distance from metal roofs, gutters, rebar walls.
- Return path: The coax shield forms the counterpoise. Install a high‑CMR choke ≈ 8 m from feedpoint or at shack entry; a ground stake often lowers RX noise and stabilizes TX impedance.
- Tuning: Trim length or slightly slope the horizontal leg to move the dip; avoid add‑on caps/coils.
- Measurement: Measure at the antenna with an analyzer; long coax can mask true impedance.
- Trim length: If resonance is low, shorten the wire a little; if high, lengthen. Small changes (~10–20 cm) make a noticeable shift.
- Slope to tune: Raising or lowering the horizontal leg slightly shifts resonance and improves SWR symmetry across the band.
- Segment centering: Choose the low (CW), mid (SSB), or upper (digital) segment of 80 m for the deepest dip. Apply the same logic on 160 m.
- Choking is not optional: Always fit a high‑CMR choke ≈ 8 m from the feedpoint (or at shack entry). Without it, tuning drifts and RX noise rises.
- Measure at the antenna: Take analyzer readings at the transformer. Long coax hides the true impedance.
VSWR Sweep
(Indicative) — measured at the feedpoint with the integrated 68:1 transformer and a high‑CMR choke ~8 m down the line. Expect small shifts with height and surroundings.
Radiation Patterns
Patterns shown are simplified models for clarity — see why we use simplified models and not NEC. Real‑world results vary with soil, height, and surroundings.
160 m
80 m
Use a high‑CMR choke ~8 m from the feedpoint, keep the horizontal leg clear and high, and trim/slope for your preferred segment. Add a ground stake to lower RX noise and stabilize impedance.
Included Accessories
- Integrated 68:1 transformer assembly
- 1 × Stainless carabiner (RVS316)
- 2 × Bulldog wire grips (RVS316)
- 1 × Ceramic egg insulator
- 1 × Stainless duplex clamp (RVS316)
- 1 × Stainless thimble (RVS316)
All accessories are stainless or weather‑proof for long‑term outdoor use.
Mini‑FAQ
- Do I need a tuner? — Yes. 160 m is narrow; 80 m won’t cover the full band with one dip.
- Can I run FT8 at legal limit? — Yes, up to 1500 W continuous duty.
- Does feedpoint height set resonance? — No. Resonance follows radiator length + geometry.
- Can I use Inverted‑U or Sloper? — Yes; impedance/pattern shift slightly. Inverted‑L is the reference.
- Where to place the choke? — About 8 m from the feedpoint or at shack entry; multiple chokes can help on long runs.
- Ground stake useful? — Often lowers RX noise and stabilizes TX impedance.
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