Portable radios are also known as walkie-talkies. In GMRS, portables can operate at 5 Watts on channels 1-7. Technically Portable radios can operate at 50 Watts on channels 15 to 22. However, no such portable radios exist. If they did exist, you would suffer radiation burns every time you used it. We all look better with eyebrows.
Portable radios are also called HT, which is short for handie-talkie.
Most bubble pack radios you buy at a retail store are not repeater capable. You can still use these bubble pack radios to talk to people on a repeater if they are nearby.
Repeater capable radios can be purchased from two way radio shops and from Amazon. They require a little bit of work to set up. But, once you have one set to use the repeater, your range increases dramatically.
Mobile radios usually refer to radios that are installed in your vehicle. Mobile radios typically have much more power than portables because the antenna is mounted elsewhere on your vehicle, which protects you from the radiation.
Lower power mobile radios can be plugged in to your cigarette lighter socket. They typically do not use enough power to burn out the cigarette lighter fuse.
Higher power mobile radios will need to be wired into your battery with a relay. The relay is optional. However, operating without a relay risks you forgetting to turn off your radio and draining the battery.
Some mobile radios are mounted within reach. Other mobile radios can be installed in your trunk with a control head set up where you can operate the radio.
You will use coaxial cables for most radio installations. Mobile radios will use coax with PL259 connectors. Repeaters and base stations will use LMR-400 coax with N-type connectors.
GMRS approved portable radios typically do not have detachable antennas. That is part of the requirements for being GMRS.
Mobile radios allow you a variety of antennas. Typically, you can get by with a UHF antenna that includes 462 and 467 MHz.
There are magnetic mount antennas for your vehicle. There are NMO antennas that you can put on your vehicle if you are willing to drill holes in it or attach fixtures that will leave a mark.
Generally, the higher up your antenna is, the further your signal will reach. There is a limit of 20 ft above your roof that an antenna is allowed to be mounted.
There are no GMRS repeaters manufactured. Typically, GMRS repeaters are commercial or amateur radio repeaters that are set up to GMRS frequencies.
Repeaters receive your transmission on 467 MHz and simultaneously rebroadcast it on 462 MHz for others to hear. This is why people on simplex are able to hear repeaters and talk to people on repeater who are nearby. The listening frequency is the same for both.
Repeaters use a duplexer, which allows them to use the same antenna to listen and broadcast on different frequencies at the same time. Without a duplexer, repeaters would need two separate antennas at a distance from each other.