GMRS Repeater Guide: Channels, Power Limits & PL Tones Explained
General Mobile Radio Service (GMRS) offers family‑friendly UHF voice communications with higher power and repeater support than unlicensed services like FRS. If you’re new to GMRS, here’s how a GMRS repeater works, which channels they use, what power limits apply, and why PL tones (CTCSS) matter.
What Is a GMRS Repeater?
A repeater is a radio station that receives your transmission on one frequency (the “input” channel), then re‑transmits it on another frequency (the “output” channel) at higher power and from a better location (often a tall tower). This lets low‑power handhelds and mobile radios talk over miles of terrain that would otherwise block line‑of‑sight VHF/UHF signals.
GMRS Repeater Channels
GMRS allocates eight paired channels specifically for repeater operation. Each pair consists of:
- Input (Rx) on the 467 MHz band
- Output (Tx) on the 462 MHz band
| Repeater Pair | Input (467 MHz) | Output (462 MHz) |
|---|---|---|
| Pair 1 | 467.5500 MHz | 462.5500 MHz |
| Pair 2 | 467.5750 MHz | 462.5750 MHz |
| Pair 3 | 467.6000 MHz | 462.6000 MHz |
| Pair 4 | 467.6250 MHz | 462.6250 MHz |
| Pair 5 | 467.6500 MHz | 462.6500 MHz |
| Pair 6 | 467.6750 MHz | 462.6750 MHz |
| Pair 7 | 467.7000 MHz | 462.7000 MHz |
| Pair 8 | 467.7250 MHz | 462.7250 MHz |
When you set your radio to “Repeater Pair 1,” you’ll transmit on 467.5500 MHz and listen on 462.5500 MHz (or vice versa, depending on how your radio labels “input” vs. “output”). Your radio’s offset (+5 MHz) handles this automatically.
Power Limits & License Requirements
GMRS repeaters can operate up to 50 W on both input and output channels. As a licensed GMRS user, you may transmit into a repeater at up to 50 W (mobile or base station), but handhelds are typically limited to 5 W or 1–2 W, depending on model and FCC rules.
- Handheld (HT): Often 1–5 W
- Mobile/Base: Up to 50 W (13.8 V DC supply)
You must hold a valid GMRS license (FCC Form 605, $35 fee, 10‑year term) to legally transmit on these channels and to use—or operate—any repeater.
PL Tones (CTCSS) & Access Control
Most GMRS repeaters require a PL tone (Private Line, a Motorola brand term) or CTCSS (Continuous Tone‑Controlled Squelch System) to activate the repeater’s receiver. Here’s why:
- Selective Access: The repeater “listens” only for transmissions carrying its specific CTCSS code (e.g., 103.5 Hz). That keeps out random chatter or noise on the same frequency.
- Noise Rejection: CTCSS helps eliminate static and interference from other nearby users not using the correct tone.
- Multiple Users: In areas with several repeaters, each repeater can use a unique tone so your radio switches only the desired machine.
To program your radio, you enter the repeater’s uplink frequency, set the +5 MHz offset, and specify the CTCSS tone (commonly 103.5 Hz for many GMRS repeaters). When you key up, your radio sends both voice and the continuous tone; when the repeater detects the tone, it keys its transmitter and relays your signal.
Duplex vs. Simplex Operation
- Simplex means you transmit and receive on the same frequency (e.g., two‑way on 462.5500 MHz without a repeater). GMRS also allows simplex on certain channels (the eight interstitial FRS‑shared channels and seven exclusive GMRS channels at 462.550–462.725 MHz).
- Duplex (Repeater) uses different transmit/receive frequencies (the pairs in the table above) so the repeater can operate its receiver and transmitter simultaneously.
Your radio’s “duplex” or “repeater” mode handles this automatically. Just select the repeater channel, and the radio knows to transmit on the 467 MHz uplink and receive on the 462 MHz downlink—with the programmed offset and tone.
Finding & Coordinating Repeaters
- Directories: Online resources like RadioReference.com list local GMRS repeaters, their frequencies, PL tones, operating hours, and coverage maps.
- Clubs & Groups: Many ham clubs and GMRS user groups host or maintain repeaters—check club websites or Facebook groups.
- Etiquette: Always listen first to ensure the repeater is free, follow time‑out limits (e.g. 3 minutes per transmission), and ID with your call sign as required (end of each transmission).
Why Use a GMRS Repeater?
- Extended Range: A handheld’s 1–5 W signal can reach 20–30 miles via a well‑sited repeater—even across hills or valleys.
- Group Coordination: Perfect for family convoys, community events, search‑and‑rescue, or off‑road outings where everyone shares a common talk‑group.
- Reliable Coverage: Repeaters often have backup power and sturdy antennas—offering more consistent communications than handheld‑to‑handheld links.
Key Takeaways
- GMRS repeaters use eight paired frequencies (467 MHz uplink to 462 MHz downlink).
- Power: Handhelds (1–5 W); mobiles/base stations (up to 50 W).
- CTCSS/PL tones gate access and cut noise—each repeater has its own tone (e.g., 103.5 Hz).
- Duplex mode with +5 MHz offset lets you key the uplink while hearing the downlink.
- License required: A $35, 10‑year FCC GMRS license covers you and your immediate family.
By understanding these basics, you’ll be ready to program your radio, hit the local GMRS repeater, and enjoy reliable, long‑range UHF voice communications with your family and friends.