Best Coax Cable for Ham Radio

RG-58 vs RG-8X vs LMR-240 vs LMR-400: loss compared

Coax is rated by loss per 100 feet at a given frequency. Lower is better. Loss rises with frequency, so a cable that looks fine on HF can be poor on 70cm. The table below shows typical attenuation for common cables at the three bands beginners use most. Numbers are approximate and vary by manufacturer, so always check the datasheet for the exact cable you buy.

Read it as: at 446 MHz, 100 ft of RG-58 throws away about 11 dB, which is over 90% of your power, while LMR-400 loses under 3 dB. Most beginner runs are far shorter than 100 ft, so scale the number down. To see the exact loss for your length and frequency, use the coax loss calculator, it does the math and shows watts delivered at the antenna.

A quick rule of thumb: 3 dB of loss halves your power. Keep total feedline loss under about 3 dB and you will barely notice it; past 6 dB you are giving away most of your signal in both directions.

Match the cable to your run length and band

There is no single "best" coax, only the best coax for a given length and frequency. Use these practical brackets for VHF/UHF, where loss bites hardest:

Two things shift you toward better coax: higher frequency and longer runs. A 30 ft run that is acceptable on 2m may be marginal on 70cm, so if you operate both, size for the higher band. On HF, cable choice is far more forgiving; even RG-8X over 50 ft is fine at 40m. Before you commit to a length, plug it into the coax loss calculator and compare RG-8X against LMR-240 side by side, the difference in delivered watts is often what decides it.

Connectors: PL-259/SO-239, SMA, and N

The cable is only half the feedline; the connectors on each end have to match your radio and antenna, and a bad connector can add more loss than the coax itself. The three families beginners meet:

• PL-259 / SO-239 (UHF connector): the ham standard for HF and most VHF/UHF mobiles and base rigs. The male PL-259 plug mates with the female SO-239 jack on the radio and antenna mount. Despite the name, it is used well into UHF.
• SMA: the small threaded connector on handheld radios. Note the gender trap, Baofeng, Quansheng, and TIDRADIO HTs use SMA-Female on the radio (antenna is SMA-Male), while Yaesu and Icom HTs use SMA-Male on the radio. Get this backward and nothing threads on.
• N connector: a weatherproof, lower-loss connector preferred for outdoor runs above ~150 MHz. Common on quality base antennas and LMR-400 assemblies.

If your radio and cable ends do not match, use a proper adapter rather than forcing parts. A short programming cable is unrelated, but the same catalog has RF adapters: sma-f-to-so239 lets an HT feed a mobile antenna, sma-m-to-bnc and nmo-to-so239 cover other common conversions. Keep adapter count low, every junction adds a little loss and one more thing to fail.

Avoid cheap, lossy patch cables

The most common beginner mistake is a bargain "RG-58" or unlabeled jumper bought purely on price. Problems to watch for:

• Copper-clad aluminum (CCA) or steel shields instead of copper, which raises loss and resistance.
• Thin, low-coverage braid that leaks signal and picks up noise.
• Molded connectors crimped poorly, a frequent source of high SWR and intermittent contact.
• Mystery length and mystery spec, no datasheet means you cannot predict loss.

Buy assemblies from a known brand with a stated cable type and soldered or properly crimped connectors. On a short HT jumper the loss penalty of a cheap cable is small, but as a mast or roof feedline it can cost you more signal than upgrading your antenna would gain back. If you suspect a bad cable, a quick check with an SWR reading or an SWR meter will often reveal a connector fault as high or erratic SWR.

Our coax and adapter picks

These are the exact cables and adapters we reference for beginner setups. Choose by run length first, then confirm the connectors match your radio and antenna.

• RG-8X, 18 ft (mpd-rg8x-18ft): the everyday choice for mobile installs, balcony antennas, and short base runs. Low enough loss for 2m and 70cm at this length, flexible, and terminated in PL-259 for standard mounts.
• LMR-240, 25 ft (times-lmr240-25ft): step up here for attic and roof runs or heavy 70cm use, where its lower loss noticeably out-delivers RG-8X while staying manageable to route.
• RG-58, 15 ft (abbree-rg58-15ft): a budget short jumper. Fine for a quick indoor test lead or an HT hookup under a few feet, not a feedline for a distant antenna.

For gender and standard mismatches, keep sma-f-to-so239, sma-m-to-bnc, and nmo-to-so239 adapters on hand. Pair any of these with the right antenna, see our 2-meter mobile antenna guide, and verify the whole system with an SWR check before you transmit at full power.

Installing and caring for coax

Good cable installed badly still loses signal. A few habits protect your investment:

• Do not exceed the minimum bend radius. Kinking coax changes its impedance and permanently raises loss. Thicker LMR-400 needs gentler bends than RG-8X.
• Weatherproof outdoor connectors with self-amalgamating tape. Water wicking into coax is a top cause of rising loss and high SWR over time.
• Support the weight so the connectors are not carrying the cable's load, which stresses solder joints.
• Keep runs as short as practical. The cheapest way to cut loss is to not buy extra feet you will coil up.

If you are running coax from a roof or mast, read our grounding and lightning protection guide before drilling anything, and review antenna basics so the feedline and antenna work together.