A rather frequent question that arises on our two-way radios is "What is the Power?" The below table lists the power output from our current (as of 3/2015) models. Note that "ERP" means "Effective Radiated Power" and is the actual RF energy that comes out of the antenna. This is the power rating that the FCC uses to determine whether the radio is legally operating. We've included "Conducted" power on some models, where such test was performed. Note that Conducted power is the power used by the radio's final transistor (pretty close to the power being drawn from the battery pack during transmit) and is not really useful energy, as anything that is not actually radiatiated is dispersed as heat, and not a transmitted signal. You may find some manufacturers touting 5W radios in this class...you can be certain in these cases that they are quoting the conducted power, not the ERP. Want to know what the radio is really putting out? Go to http://transition.fcc.gov/oet/ea/fccid/ and enter the radio's FCC ID number (it is on a label either on the back of the radio or in the battery compartment of the radio). Look for either the SAR report or the test report.

All models output at the lowest power level on the 7 channels allocated solely to the Family Radio Service (channels 8-14). Other channels might transmit at a higher power level on other channels, and radios that have a "Boost" feature can boost the power on those non-FRS channels.

ModelFCC IDERP HI (BOOST)/LOW (W)Conducted HI/LOW (W)
GMR1635AMWUT0300.23/0.220.61/0.58
GMR1636-2CAMWUT055.22/.2 (Industry Canada)
GMR2638-2CKAMWUT063.62/.41
GMR2838-2CKAMWUT051.75/.27
GMR3040-2CKHSAMWUT063.62/.41
GMR3040-3CKAMWUT063.62/.41
GMR3740-3CKAMWUT063.62/.41
GMR3799-2CKHSAMWUT063.62/.41
GMR4040-2CKHSAMWUT064.65 (.92)/.39
GMR5089-2CKHSAMWUT052.75 (1.53)/.462.35 (3.22)/1.58
GMR5088-2CKHS AMWON5095.75 (1.92)/.44.77(1.97)/.49
GMR5095-2CKHS AMWON5095.75 (1.92)/.44.77(1.97)/.49
GMR6000-2CKHSAMWUT052.75 (1.53)/.462.35 (3.22)/1.58
GMR6000-2CKHSAMWUT052.75 (1.53)/.462.35 (3.22)/1.58

You should note that the range of two-way radios of this class are typically a factor of terrain, not of power level. Signals cannot deeply penetrate buildings, are weakened by foliage, and are completely blocked by terrain (any ground that lifts between the two radio users). The signals also do not curve around objects or follow the curvature of the earth. For someone standing on perfectly level ground, the horizon is typically less than 3 miles away, so the absolute range limit of two radios held by users on flat, level terrain is about 5 miles. Of course, flat, level terrain is not common (unless you are standing on a frozen sea), so realized range is going to vary based on the topography where you are.

To get extreme range, one user needs to be significantly elevated above the average terrain with a clear, unobstructed line-of-sight to the location of the other user. This is, in fact, how the range of the above radios was validated. In those conditions, two factors determine the achievable range: power output and radio system sensitivity (combination of antenna efficiency and the radio circuit's absolute sensitivity).