GMRS base station setup Radio, power supply, antenna and coax

How this guide works: radios are compared on their FCC grants and maker pages; power supplies, antennas and coax on their makers' published specs. We haven't done hands-on testing, so we don't rate audio, range or build quality.

What r/gmrs asks about base stations

Most base-station threads are the same few questions from people who’ve never put up an antenna: what to buy, how to power it, and how to ground it without drilling the roof (How hard is it to set up a base station?, Can someone explain the cost of power supplies?, HT for outdoor patio). Owners post their builds too, many of them a mobile radio on a desk (I have a DB20-G as a base station and one in my car, My GMRS base station, Base Station Complete (for now)).

What the rules say

• Definition: a base station is “a station at a fixed location that communicates directly with mobile stations and other base stations” (§95.303).
• Power: “The transmitter output power of mobile, repeater and base stations must not exceed 50 Watts” on the main channels, and base stations are limited to 5 W ERP on the 462 MHz interstitials (§95.1767).
• Channels: base stations may transmit on the 462 MHz main and interstitial channels. The 467 MHz channels are for repeater inputs and handhelds (§95.1763). A home radio that talks through a repeater counts as a control station, which may use the 467 MHz inputs only through a repeater.
• License: your individual GMRS license covers a base station. No separate license is needed (how to get one).
• Height: structures more than 200 ft above ground may need FAA notification and FCC registration, and limits are lower near airports (§95.317).

Step 1: the radio

Any GMRS mobile works as a base. These have documented features that suit a desk:

Best documented value: BTECH GMRS-50V2

Filed at 44.87 W ERP on the 462 MHz main channels (2AGND50V2G). It has 256 channels, quad watch and NOAA receive, and costs $219.89 on BTECH’s site. It draws a 20 A peak, so it needs a real power supply, not a wall wart. The grant sets an 80 cm antenna distance, which is easy to meet with an outdoor antenna. Full specs.

Budget base: BTECH GMRS-20V2

$109.89, filed at 18.41 W ERP (2AGND20V2G). BTECH markets it for “home, shop, cabin, farm, or emergency use.” It has 200 channels, NOAA receive and an SO-239 jack, and it’s small (14.9 oz). About 4 dB less power than the 50 W radios matters most on long simplex links. Through a repeater, the repeater does most of the work. Full specs.

Other documented options

• BTECH GMRS-50PRO: phone-app programming over Bluetooth, GPS and a color mic, at 35.4 W ERP filed and $284.89. Its grant’s 1.0 dBi antenna-gain condition rules out most gain base antennas.
• Midland MXT275: includes a 2.1 dB magnet-mount antenna, 15.0 W conducted, $199.99. Its grant caps antenna gain at 2.15 dBi.
• Radioddity DB20-G: 500 channels and CHIRP support, $109.99. Its grant has no separate 462 MHz main-channel row (see spec page).
• A handheld on a desk charger works for short range, and you can add an outdoor antenna later. Mind the handheld ERP limits if you do (vehicle antennas).

Compare all of them in best GMRS mobile radios.

Step 2: the power supply

A mobile radio needs 13.8 V DC at its peak current. BTECH lists 20 A peak for the GMRS-50V2 and GMRS-20V2. A regulated supply with headroom above that keeps the voltage steady on transmit.

BTECH RPS-30M

$99.89. 13.8 V regulated, 30 A peak and 25 A constant, with screw terminals and a cigarette-style socket. BTECH says it has overheat, short and surge protection and is “designed to be immune from radio frequency interference at close range.” BTECH also sells the RPS-30PRO ($149.89) with snap-in terminals added.

Battery backup: a 12 V battery can run any of these radios when the power is out. A 20 W radio draws less on transmit, which stretches the battery. We haven’t verified current-draw figures beyond the 20 A peaks BTECH lists.

Step 3: the antenna

Antenna height does more for range than radio power. GMRS range has the radio-horizon arithmetic: raising an antenna from 5 ft to 30 ft moves the horizon from about 3.2 to 7.7 miles.

Starter (no drilling): a magnet-mount antenna on a metal sheet in a window or attic. BTECH suggests this for the Nagoya UT-72G: “place it on a baking sheet or any metallic surface.” It’s a cheap way to start, and you can move the antenna to the car later. UT-72G details and grant fit.

Outdoor mast: an NMO antenna on a ground-plane kit gets above the roofline. The Nagoya GPK-01 ($33.98) clamps to a 2 in pole or mast, gives an NMO antenna four 21 in radials, and BTECH lists a “100 MPH wind load capacity.” It has an SO-239 and needs 50-ohm coax with PL-259 ends. You’ll also need an NMO antenna tuned for GMRS. BTECH’s own GMRS NMO antenna (the NMO-HDG) is out of stock.

Purpose-built GMRS base antennas (fiberglass collinears) are another route. We haven’t added any to our database yet, so we can’t compare their specs.

Step 4: coax

At 462 MHz, cable loss adds up fast. These figures come from Times Microwave’s datasheets at 450 MHz (LMR-400: 2.7 dB per 100 ft; LMR-195, a drop-in replacement for RG-58: 7.8 dB per 100 ft). The percentage is how much of the radio’s power reaches the antenna. It’s arithmetic, not a measurement.

On a 50 ft run, thin cable throws away more power than the difference between a 20 W and a 50 W radio (about 4 dB). r/gmrs asks the same question in “height is might” vs signal loss on long runs and Does antenna height become counter productive at a certain cable length?. The short answer: height usually wins, as long as the cable is low-loss.

Step 5: grounding and safety

• Lightning and grounding: an outdoor antenna and mast should be grounded. In the US, Article 810 of the National Electrical Code covers radio antenna systems. If you’re not sure, have an electrician look at it. This is the part new base-station builders ask about most.
• RF exposure: keep the antenna at least the distance on your radio’s grant from people: 80 cm for the GMRS-50V2, 49 cm for the GMRS-20V2 and 40 cm for the GMRS-50PRO. Every mobile’s figure is in vehicle antennas.
• Station ID: say your call sign at the end of a transmission or series and every 15 minutes (call signs and station ID).

Shopping list

Related: GMRS vehicle antennas · best GMRS mobile radios · GMRS range · repeaters and mobile setup · GMRS-50V2 vs MXT500