Coax Cable and Connectors
Setup & Programming
The coax cable between your radio and antenna carries your signal in both directions. A poor cable or bad connector can lose more signal than you'd gain by doubling your transmit power. Understanding your options helps you choose the right cable for your setup.
Coax cable types
At GMRS frequencies (462-467 MHz), signal loss in coax cable is significant — much more than at lower frequencies. Shorter runs with better cable make a real difference.
- RG-58: thin (~5mm), flexible, inexpensive. Loses about 6.5 dB per 100 feet at 462 MHz. That's a 75% signal loss. Only acceptable for very short runs under 10 feet, such as a short jumper between a radio and a nearby antenna switch
- RG-8X (mini-8): mid-size (~6mm), moderate loss — about 4.5 dB per 100 feet. A good compromise for mobile installs where flexibility matters and runs are 10-25 feet
- RG-213 / RG-8U: thicker (~10mm), about 3.5 dB per 100 feet. Decent for moderate base station runs. Less flexible than RG-8X
- LMR-400: thick (~10mm), low loss — about 1.5 dB per 100 feet. The standard choice for base station installations. Worth the extra cost for any run over 25 feet. Stiff and harder to route, but the performance is dramatically better
Rule of thumb: Every 3 dB of loss cuts your signal in half. A 50-foot run of RG-58 loses about 3.25 dB — you're throwing away more than half your signal before it even reaches the antenna. The same run in LMR-400 loses less than 0.75 dB. For a base station, LMR-400 pays for itself immediately.
Connector types
- PL-259 / SO-239: the most common connector for mobile and base station GMRS radios. PL-259 is the male plug; SO-239 is the female jack (on the radio). Sometimes called "UHF connectors," despite being designed decades ago for what was then considered UHF
- SMA: a small threaded connector used on handheld radios. SMA-Male has a center pin and external threads; SMA-Female has a center socket and internal threads. Note that different radio brands reverse which gender is on the radio versus the antenna — always check before ordering
- BNC: a quick-connect bayonet-style connector found on some test equipment and older radios. Easy to connect and disconnect. Less common on GMRS gear
- N-type: a precision connector used on higher-end antennas and commercial equipment. Better weatherproofing and lower loss than PL-259 at UHF frequencies. Some base station antennas use N connectors
Minimizing signal loss
- Keep runs short: route cable by the most direct path. Every extra foot costs signal
- Use quality connectors: cheap connectors with poor solder joints or loose fittings add loss and create intermittent problems. Crimp-on connectors designed for your cable type are more reliable than universal-fit types
- Weatherproof outdoor connections: wrap outdoor connections with self-amalgamating (self-vulcanizing) tape, then cover with electrical tape. Moisture in a connector causes corrosion and signal loss
- Avoid adapters: each adapter in the signal path adds a small amount of loss. If you need to go from PL-259 to SMA, use a single adapter rather than chaining multiple connectors
- Don't kink the cable: sharp bends damage the cable's internal geometry and increase loss. Follow the manufacturer's minimum bend radius