EFHW-xfrms

These are our MEF (Multiband End Fed) transformers — high-ratio 49:1, 56:1, 75:1, and 81:1 UNUNs (~2500, 2800, 3750, or 4050:50 ohms) for EFHW antennas. Pick the model for your bands and power, add a half-wave wire, and you have a resonant multiband antenna: wire length in feet = 468 ÷ frequency in MHz. The average insertion losses — published with measured charts on every product page — run 0.1–0.5 dB, unmatched by any similar transformer on the market.

Choosing your MEF is two decisions. First, your lowest band: MEF-130 series covers 1–30 MHz including 160m; MEF-330 covers 3–30 MHz (80m up); MEF-530 covers 5–30 MHz (40m up); the MEF-104 and MEF-107 are the 160m low-band specialists; the MEF-307 is the 80/40m specialist. Second, your power: LP for portable and 100W-class, 1K-Plus and 2K-Plus with three 3-inch cores for high power, and 3K/4K/5K models for the biggest stations.

Building your first end-fed? The full guide — theory, wire trimming, installation configurations, and SWR expectations — is in All About EFHW Antennas, written by Danny Horvat, E73M/N4EXA, who designs and measures every transformer on this page.