Can I Use a PL-259 Connector with RG-58 C/U Coax for AIS?

Yes, you can use a PL-259 connector with RG-58 C/U coaxial cable for an AIS installation, as both share the 50-ohm impedance required by marine transceivers. Because RG-58 has high signal loss at 162 MHz, you should restrict this cable to short runs under 10 metres, such as wiring a pushpit antenna.

Matching Cable and Connector

RG-58 C/U is a standard marine cable. The C/U designation indicates a centre conductor made of stranded, tinned copper. This construction handles engine vibration far better than solid-core wire and resists corrosion. It provides the exact 50-ohm impedance needed for marine VHF and AIS equipment.

The PL-259 plug fits the SO-239 socket on your AIS unit. Manufacturers size standard PL-259 plugs for thicker 10mm cable like RG-213. To fit 5mm RG-58, you need a PL-259 with a narrow neck machined specifically for this diameter, or a standard PL-259 fitted with a UG-175 reducer adapter. The reducer threads into the back of the plug, gripping the outer jacket and providing a surface to solder the braid.

Signal Loss at 162 MHz

AIS operates on 161.975 MHz and 162.025 MHz. At these frequencies, RG-58 cable loses about 2 decibels of signal strength per 10 metres. AIS transceivers output just 2 watts for Class B or 5 watts for Class B SOTDMA. You cannot afford to waste power heating the cable.

For an antenna mounted on an A-frame or stern pole, a 5-metre run of RG-58 works well and costs about 1 dB of loss. If you are wiring a masthead antenna on a 15-metre sailing yacht, RG-58 is the wrong choice. A 20-metre run eats nearly 4 dB of signal, meaning more than half your transmit power never reaches the antenna. For masthead runs, upgrade to a low-loss 10mm cable like RG-213 or Aircell 7, or an intermediate 6mm cable like RG-8X.

Crimping Versus Soldering

You can attach a PL-259 by soldering or crimping. Aboard a yacht, a high-quality crimp beats solder for the outer braid because it resists fracturing under constant movement.

• Crimp connectors: Use a ratcheting hex crimper. For RG-58, the hex die size for the outer ferrule is 5.4mm. You can crimp the centre pin with a 1.72mm die or solder it.
• Solder connectors: If you must solder the shield, use a hot iron of at least 60 watts. This heats the connector body quickly without melting the internal polyethylene dielectric. Use 60/40 rosin-core electrical solder. Never use plumbing solder or acid flux, which will corrode the fine copper strands within months.