The GMR30 also has the ability to use GMRS Repeaters, which the 22 channel GMRS blister pack radios do not.
I regularly check into the Monday night 1900 hours net conducted via the High Potosi 462.625 GMRS repeater from my living room here in Pahrump, via a GMR30 with a super rubber duck antenna and the radio set to the .5 watt low power setting, with the standard short rubber duck antenna that it came with, I can do the same with it set to the high, 5 watt position.
Line of sight at 5 watts UHF can have a pretty great distance with no objects in the way, over totally flat ground or water (lake, ocean, great plains, etc. ) it wil often reach 100 miles or more with a good antenna.
A buddy of mine worked the high potosi 2 meter repeater from Stella's cabin out in stripped butte valley in Death Valley with a 5 watt 2 meter hand held, also considered a line of sight band, with a small 3 dB gain mag mount antenna on the roof of his 4x4, line of sight distance there was 127 miles.
A couple of keys to making contact, beyond power and a good antenna that is, is the ground plane and antenna orientation.
Too many folks imitate what they see on TV and the movies, with folks holding a handheld in a manner that looks tacti-cool, radio and antenna parallel to the ground.
Problem is, unless the other receiving station also has its antenna horizontally polarized (parallel to the ground) the intercept point for the signal becomes very small.
If one antenna is held vertically, and the other horizontally, the intercept point for the RF (Radio Frequency) signal is the point where the two planes cross, very small.
If both antennas are oriented in the same plane, then the entire length of the antenna is the intercept point, much great signal capture area that way!
At low power, both 2 meter (140-148 MHz) and UHF (420-470 MHz) tend to travel a bit farther if vertically polarized, that is, the antennas on both the transmit and receive stations are both perpendicular to the ground.
Notice that bolded word "GROUND" appearing a number of times above.
The radio signal needs something to push off from, in order to travel any distance at all.
Otherwise, it's like a car with slick tires, covered in grease, on smooth glass, no matter how much horsepower is fed to the wheels, you are not going anywhere very fast or far.
The GROUND PLANE for a handheld radio is............wait for it...................YOUR BODY!
Yup, through capacitive coupling, YOU become the ground plane when you hold the radio in your hand.
Need to increase the range of a handheld?
It's easy.
Cut a piece of light gauge wire, say, 26 to 30 gauge, to a length of 1/4 or 1/8th wavelength for the frequency you are going to transmit on.
How do you figure that out>
Easy.
For a 1/4 wavelength, divide 236 by the frequency in MHz (Mega Hertz).
For a GMRS transmit frequency of say, 467.625 MHz (that's the High Potosi input frequency by the way, all GMRS repeaters operate at a PLUS 5 MHz shift up from their transmit frequency),
234/462.625 =.510 feet.
So you cut a wire about 7 inches long (6 inches for the .510 feet, plus an inch for the loop) and you strip bare the last inch of wire, form a loop, unscrew the antenna off the hand held (which you CAN NOT do with those blister back GMRS or FRS radios by the way, but you CAN with the Radioddity GMR30) drop the bare loop over the external threads of the radio's antenna connector, and screw the antenna back on.
Let the remaining 6 inches of wire hang down the side of the radio, now when you transmit, you have a good electrically connected ground plane in addition to the piss poor capacitively connected ground plane of your body.
Distance for transmitting a clear signal jumps up significantly. Doesn't do much on the receive side, helps a little there, but the big gain is on the transmit side.
For an 1/8 wavelength, divide 118 by the frequency in MHz
For a half wave, 468, full wave, 936.
The above trick works on any frequency in a handheld that has a detachable antenna.
