End-Fed Random Wire (EFRW) 9:1 UNUN – Unbalanced to Unbalanced Transformer

The 9:1 UNUN is designed to transform 450Ω down to 50Ω, making it an essential component for an efficient random wire antenna system. Built with our Radio-Stuff.com PCB and high-quality stainless steel components, this UNUN is engineered for durability.

Why Choose Our 9:1 UNUN?

Unlike many competitors, we offer our 9:1 UNUN in two optimized core configurations:

• Micrometals T200-2 Core – Best suited for 40m–6m bands
• Fair-Rite T240-43 Core – Ideal for 80m–30m bands

While both cores can operate across 80m to 6m (with a high-quality ATU), we recommend selecting the core best suited to your primary operating bands.

Not sure which to choose?

The T200-2 core offers the most flexibility down to 80m but performs best from 40m–10m. This is our recommended choice unless you primarily operate below 40m.

Performance & Build Quality

Our 9:1 UNUN is rated at 400W (with a 450Ω antenna wire). Unlike some resellers, we do not overstate power ratings—our figures are based on real-world performance.

Key Features

• Custom-designed Radio-Stuff.com PCB (UK-engineered)
• Choice of Micrometals T200-2 or Fair-Rite FT240-43 Core
• IP-rated ABS enclosure for weatherproof protection
• M5 & M3 fittings (bolts, nuts, wing nuts, solder tabs, wire crimp connectors)
• High-quality SO-239 connector
• Antenna wire thimble & cable clamp for secure installation

Important Usage Notes for best results:

• Use a 450ohm random wire (search "random wire antenna lengths" for guidance).
• A good ground system, counterpoise or radials is required for optimal performance.
•  An ATU (Antenna Tuning Unit) is highly recommended if you plan to operate across multiple bands.
• Power handling will depends on your tuning: Contact us for more details on how tuning affects performance.

Note

 A Common Mode Choke (CMC) is required at the transceiver side to eliminate unwanted RF issues. Our 400W CMC is the perfect companion for this UNUN—check out our other products for details.