Ham Radio Coaxial Cable Guide: RG58 vs RG8X vs LMR400

The Hidden Bottleneck in Your Antenna System

You bought a great antenna. You mounted it high. You ran 50 feet of the wrong coax cable — and lost half your signal before it reached the antenna. Here is how to choose the right cable.

Coax Types Compared

Cable Diameter Loss per 100ft (440MHz) Best For
RG58 5mm 11.2 dB Short runs under 25ft, portable
RG8X 6mm 7.8 dB Good all-around, 25-50ft runs
LMR240 6mm 5.2 dB Better than RG8X, same size
LMR400 10mm 2.7 dB Long runs 50-100ft, lowest loss

What Cable Loss Means

Every 3 dB of loss = half your power is gone before reaching the antenna. 11 dB loss (RG58 at 100ft on 440MHz) means only about 8% of your 5W reaches the antenna — that is 0.4W. Choose your cable wisely.

Recommendation for Most Operators

  • Portable / field ops: RG58 — lightweight, flexible, short runs
  • Home base station: LMR400 — lowest loss, worth the thicker cable
  • Mobile install: RG8X or LMR240 — good compromise

Start with UV-K1(8) →

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