Mobile & home stations
A vehicle or home installation can improve antenna placement, operating comfort, and power availability. The radio service still determines which equipment, power, modes, and antennas are allowed.
Service comes before installation
“Mobile” and “base” describe how a station is used; they do not create one shared power class.
| Service | Power ceiling | FCC rule |
|---|---|---|
| GMRS | Channels 1–7: 5 W ERP. Channels 8–14: 0.5 W ERP, handhelds only. Main channels: up to 50 W transmitter output for mobile, base, and repeater stations; 15 W for fixed stations. | §95.1767 |
| FRS | Channels 1–7 and 15–22: 2 W ERP. Channels 8–14: 0.5 W ERP. | §95.567 |
| CB (CBRS) | AM/FM: 4 W mean carrier power. SSB: 12 W peak envelope power (PEP). | §95.967 |
| MURS | 2 W transmitter output. | §95.2767 |
ERP includes antenna gain relative to a dipole and feed-line loss. Transmitter output is measured at the transmitter; PEP is peak envelope power. These are regulatory ceilings, not a promise of a particular radio's output or range.
| Service | Vehicle or home considerations |
|---|---|
| GMRS | Purpose-built mobile radios and external UHF antennas are common. Main-channel limits distinguish mobile, base, repeater, and fixed stations. |
| FRS | FRS radios remain self-contained with integral antennas. A vehicle cradle or indoor location does not authorize an external antenna connection. |
| CB (CBRS) | Match AM, FM, or SSB with the stations you need to contact. Antenna length, placement, bonding, and adjustment are major installation choices at 27 MHz. |
| MURS | A suitable authorized radio may use an external VHF antenna, subject to the 2 W transmitter-output limit and the MURS antenna-height rule. Repeaters are prohibited. |
Antenna-height rules: CB §95.941 · MURS §95.2741. Prohibited uses: CB §95.933 · MURS §95.2733.
Plan vehicle power from the manual
Current draw, cable size, fuse placement, and grounding path depend on the exact radio and vehicle.
Before routing cable
- Read the radio manufacturer's installation and fuse instructions.
- Confirm the vehicle voltage, ground system, available circuit capacity, cable length, and expected transmit current.
- Size conductors and overcurrent protection for the equipment and route; protect the positive feed close to the battery or other source.
- Keep wiring away from heat, sharp edges, pedals, airbags, and moving parts. Use a grommet or other protected pass-through at sheet metal.
- Choose the antenna location only after checking cable routing, clearance, weather sealing, and the antenna's ground-plane, counterpoise, or bonding requirements.
Home power and feed line
Choose components from measured or specified requirements.
A radio intended for nominal 13.8 V DC needs a regulated supply, or a suitably fused battery, with the voltage range, continuous current, and transmit-duty capacity its manual requires. Leave sensible headroom, but take the figure from the manual rather than a rule of thumb.
Feed-line loss rises with frequency and length and varies by cable type and connectors. Compare the manufacturer's attenuation at the operating frequency, then account for the actual run; see antennas and feed lines. Thicker cable can reduce loss but adds cost, stiffness, weight, and connector strain.
GMRS station definitions
This distinction applies to the GMRS limits shown here.
A fixed station is a station at a fixed location that directly communicates with other fixed stations only; a base station is a station at a fixed location that communicates directly with mobile stations and other base stations. The definition follows who the station communicates with, not whether its antenna is directional.
- 50 W transmitter output — mobile, repeater and base stations
- 15 W transmitter output — fixed stations only