EXTRAFLEX BURY 7

7.3mm Armoured Ultra-Flexible 50 Ohm Coaxial Cable

The Extraflex Bury 7 is the heavy-duty, fully waterproof, direct-burial evolution of the famous Ultraflex 7. Developed specifically to withstand the harshest environmental conditions, this cable features a special tear-resistant jacket and a protective anti-oxidation layer of Petrol Jelly applied directly to the braid, making it immune to the weather and perfect for underground or outdoor runs.

10mm performance in just 7.3mm diameter

Despite its compact size (just 7.3 mm outer diameter), the Extraflex Bury 7 delivers performance so high that it clearly outclasses the classic, bulky RG 213 U (10.3 mm), overshadowing any competing cable in the same category. The stranded centre conductor ensures extreme flexibility, making it ideal for tight bends, antenna rotator installations and high-performance lab jumpers.

Key and Construction Features

• Fully Burial-Rated and Waterproof: Sealed internally with a special hydrophobic petroleum gel compound (Petrol Jelly) that blocks every possible water path and prevents oxidation of the copper shield in case of accidental cuts.
• Class A++ Double Shielding: Made of a copper tape with applied PE layer and a high-coverage copper wire braid (120 wires). This combination ensures formidable shielding efficiency (≥ 105 dB) against impulsive and environmental electromagnetic interference.
• Reinforced PE Outer Jacket: Black high-density polyethylene jacket, resistant to UV rays, soil acids, seawater, foot traffic and mechanical tearing when pulled through rough conduits.
• Geometric Stranded Centre Conductor: The inner conductor consists of 19 geometrically stranded copper wires. This design prevents impedance variations in tight bends and ensures unbeatable longevity in rotator systems.
• Efficiency and High Velocity Factor: The triple-layer foamed polyethylene dielectric (Physical Gas Injected Foam) ensures a velocity factor of 83%, minimising attenuation at higher frequencies.

Use Cases and Practical Tips

The versatility of the Extraflex Bury 7 makes it the cable of choice in many radio applications:

• Outdoor and Concealed Runs: Ideal for running from the roof/garden to the radio shack through damp conduits or buried directly in the ground.
• Wiring Antenna Systems with Rotator: Its extraordinary flexibility makes it the perfect candidate for the rotation loop around the mast, preventing breakage from mechanical stress.
• Portable Operation, CB Stations and Data Connectivity: Excellent for mobile use (SOTA/POTA), urban CB stations, outdoor 4G / LTE modem router wiring and for making terminated lab pigtails for RF amplifiers and instruments.

HRS tip: Since this cable contains an internal water-repellent protective gel, when fitting connectors we recommend carefully cleaning any surface residue of conductive Petrol Jelly from the braid before soldering or crimping, to ensure a perfect and long-lasting electrical contact.

The HamRadioShop Team's Opinion

"The Extraflex Bury 7 is a true engineering masterpiece for outdoor and buried use. It definitively solves the problem of ageing in cables exposed to sun and underground moisture thanks to the Petrol Jelly protective barrier. For the demanding radio amateur or installer who does not want to replace the feed line after a few years, it is an exceptional investment that combines the easy installation of a 7mm cable with benchmark RF performance."

General Technical Specifications

Attenuation and Power Handling Table

The values below indicate the nominal total attenuation per 100 metres of cable and the maximum continuous power (CW) at an ambient temperature of 40°C.