How much power can an RG58 handle into a 2.5 sq mm wire inverted V dipole antenna?

The short answer is that in a typical HF setup (like the 80m band) with a well-matched antenna, standard RG58 coax can safely handle 400 to 500 Watts PEP on SSB or CW, and about 150 to 200 Watts continuous duty (like FT8, RTTY, or AM).

However, your actual power limit isn’t determined by a single static number. It depends heavily on frequency, SWR, and the duty cycle of your operating mode.

Here is exactly how the RG58, the 2.5 mm² wire, and the Inverted V geometry interact to define your system’s true power handling limits.

1. The Bottleneck: RG58 Coaxial Cable

In this configuration, your 2.5 mm² copper wire (roughly equivalent to 13 AWG) is incredibly robust. It can easily handle well over 1 to 2 kW of RF power without breaking a sweat. Your power limit is entirely dictated by the RG58 coax.

RG58 is a thin, lossy cable with a solid or stranded center conductor and a polyethylene or foam dielectric. Its power handling is limited by thermal breakdown—if it gets too hot, the dielectric melts, causing a short circuit.

Baseline Power Handling (at 1:1 SWR, matched load)

• 3.5 MHz (80m band): ~800 W continuous / ~1500 W PEP
• 7.0 MHz (40m band): ~600 W continuous / ~1200 W PEP
• 14 MHz (20m band): ~400 W continuous / ~800 W PEP
• 28 MHz (10m band): ~250 W continuous / ~500 W PEP

2. The Real-World Modifiers: SWR, Mode, and Geometry

When you feed a real-world Inverted V dipole, those ideal baseline numbers drop due to three main factors:

High SWR (Standing Wave Ratio)

An Inverted V configuration naturally lowers the feedpoint impedance from a flat dipole’s 73 Ω down to roughly 50 Ω (depending on the included angle of the apex, typically between 60 to 120 degrees).

While this geometry gives you an excellent natural match to 50 Ω coax at resonance, moving away from your center frequency will cause the SWR to rise. When SWR increases, standing waves create voltage and current peaks along the coax line.

The SWR Rule of Thumb: At an SWR of 2:1, your coax’s power handling capability drops to roughly 70% of its rated maximum. At 3:1, it drops to 50%.

Mode Duty Cycle

• SSB (Voice): Low duty cycle (~20%). The coax has time to cool down between speech peaks. You can safely run 400W PEP on HF.
• CW (Morse Code): Moderate duty cycle (~40%). Safe up to 250–300W.
• Digital (FT8 / RTTY): 100% duty cycle during transmission blocks. The coax is under constant thermal stress. Limit your power to 100–150W to prevent the internal dielectric from softening.

Summary of Safe Operating Limits

If you are running a standard layout with a good match (SWR under 1.5:1) on the lower HF bands, use these guidelines:

Operating Mode	Safe Maximum Power for RG58
FT8 / RTTY / Data	150 Watts
CW (Morse)	300 Watts
SSB (Voice PEP)	400 – 500 Watts

Pro-Tips for Your Setup:

1. Watch the Quality: High-quality RG58 (with a solid polyethylene core) handles heat significantly better than cheap, generic varieties with thin shielding or low-density foam cores.
2. Upgrade the Coax First: If you plan on deploying a 400W linear amplifier and pushing it to its limits swap the RG58 run for RG8X (Mini-8), or ideally LMR-240 / RG213. They fit standard connectors easily but offer a massive leap in thermal headroom and lower attenuation loss.