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Chameleon Knowledge Base · The Complete Online HF Antenna Handbook

What Is LMR-240 Coax?

Learn about LMR-240 coaxial cable, its characteristics, and when it is the right choice for amateur radio installations.

Getting Started HF Fundamentals Reviewed 2026-07-14
Short Answer: Learn about LMR-240 coaxial cable, its characteristics, and when it is the right choice for amateur radio installations.

Explanation

Overview LMR-240 is a low-loss 50-ohm coaxial cable designed to provide improved RF performance over smaller coaxial cables while maintaining good flexibility. Advantages Lower attenuation than RG-58 and RG-8X. Good flexibility. Excellent shielding. Suitable for indoor and outdoor use when properly installed. Typical Applications Medium-length HF feed lines. Portable stations. Base stations. VHF/UHF installations. Limitations Heavier than RG-8X. Not as low-loss as LMR-400. Selection Considerations LMR-240 is often selected when operators want lower feed-line loss than RG-8X but still require a cable that coils easily for transport. Applied to Chameleon Products LMR-240 is an excellent choice for many Chameleon portable and semi-permanent installations where moderate cable lengths and improved efficiency are desired. Related Articles What Is LMR-400 Coax? What Is RG-8X Coax? What Is Feed-Line Loss? What Is Coaxial Cable? Related Products All Chameleon Antenna Systems

The exact result depends on the complete station: frequency, geometry, feed line, matching network, return-current path, environment, operating power, and the reference plane of any measurement. A low SWR establishes an impedance relationship at that point; it does not by itself prove efficiency, radiation pattern, compatibility, or safety.

What to Verify

  • Use the newest official product guide or primary service documentation.
  • Confirm the exact model, revision, components, configuration, and operating conditions.
  • Begin tests at low power and change one variable at a time.
  • Do not infer compatibility from connector or thread fit.

Learn Next

  • Antenna Selection: A Mission-First Decision Guide
  • Engineering Design Tradeoffs in Portable HF Antennas
  • Antenna Measurement Reference Planes
  • Understanding Common-Mode Current

Source note: Independently synthesized with reference to The ARRL Handbook for Radio Communications, 99th edition (2022), and The ARRL Antenna Book for Radio Communications, 24th edition (2019). Verify changing regulations, services, software, specifications, availability, and safety requirements against current primary sources.