Today's radio control systems (radios) are far more reliable than those of just 15 years ago. Higher quality components and superior construction techniques have narrowed the differences between brands to the point where the most important factor's are the extra features offered for the higher priced models. Here are a few points to consider:
This does not refer to the radio frequencies but the number of separate control channels. Normally one channel controls one servo. There maybe several switches or controls that affect the same servo. Most power airplanes require 3-4 channels. Most new pilots will purchase a four channel radio.
There is an almost endless list of features available with the new microprocessor controlled transmitters for airplanes. The most important is servo reversing. This makes servo installation a breeze. New pilots will learn to fly without the advanced features of most radios. These features improve the performance of more advanced airplanes.
There are four major brands of radios available to American modelers. Of these only two use the same servo connectors. If you already own a radio system, it may be an advantage to select the same brand so that your servos, switches, battery packs, and chargers are interchangeable. If you are in the market for your first radio this may not be so important.
This feature allows for two transmitters to be connected by a trainer cord. One transmitter (the master) is held by the flight instructor. The other is held by the student pilot. The instructor has control of who is in control of the aircraft. This is a popular way to teach new pilots to fly. In order to connect two transmitters together, they must be of the same brand and also must be compatible with each other. If you are going to use a trainer system, you should consider this.
Most trainer power aircraft will accept the standard size servos and battery packs. However, if you are starting with an electric aircraft or a sailplane you may want to consider one of the special four channel systems offered by some manufacturers. Remember that these specialty radios are not as versatile as the standard versions and usually are more expensive.
For sailplanes, there is a version which comes with two micro servos instead of the three standard servos. It also has a smaller battery pack. This is more suitable to sailplanes where weight is critical.
For electric airplanes there are versions which include an electronic speed controller, (sometimes combined with the receiver) and two micro servos. The speed controller replaces the throttle servo and provides power for the receiver and servos. This reduces weight.
The choices here are AM, FM, or PCM. Originally all radios were AM. When FM became legal, higher quality receivers began to appear. FM adds slightly to the price of a radio but is generally considered well worth it. The advantages are mostly signal reliability. The real choice should be between FM and PCM. PCM radios are FM radios with advanced digital encoding. This allows an entire order of magnitude improvement in signal reliability. Since it is more expensive, few four channel radios incorporate PCM technology. It is usually available in the more expensive, feature laden radios of 5-9 channels. PCM may be the most significant reason for choosing a more elaborate radio with more channels and more features. It is the reliability of the radio that is important here.
Airplanes have a tendency to crash. This sometimes requires service of the radio equipment. Of the four major brands, three have service centers on the west coast. One is in the Midwest. The warranty terms of most radio brands are similar. Generally a defect shows up immediately, not a couple of years later. This is not a significant factor in the choice of a new radio purchase.
There are fifty frequencies (also called channels) for use in model airplanes plus ten more which require and Amateur Radio License. The main thing to consider here is the pit location. Each organized flying field has a designated pit area for each frequency. If you have a friend who is going to teach you how to fly, do not choose the same frequency as his. Choose a frequency in an adjacent pit area. This allows you to be close enough together for training but later you will both be able to fly at the same time.