JR XP662: An affordable, programmable radio for airplanes and helicopters!

Model Airplane News, Oct 2002 by Aberle, Bob

MODEL AIRPLANE NEWS

PRODUCT REVIEW

The very popular series of JR radios has evolved over the past few years. The latest in this JR series Is the 6-channel XP662-an excellent choice for every airplane and helicopter pilot, from novice to expert, at an affordable price of $250.

USING THE MODEL MEMORIES

The new system includes six model-memory positions (increased from three) that can be identified by number or by your choice of names, up to a limit of three characters, e.g., "Cub" for a Piper Cub model.

When you turn on the transmitter, the first screen you see is the NORMAL DISPLAY, which tells you "AC 1" (aircraft memory position 1) or "CUB" (the name of the plane), along with the transmitter voltage, for example, "10.4V."

For overall simplicity, there are only two computer input switches on the front of the transmitter. One is identified as "Scroll" and "Channel"; the other is "Increase" and "Decrease." When you scroll around the XP662 menus or when you add and subtract control inputs, you will find an interesting feature: quickly pushing the "Scroll/Channel" or "Increase/Decrease" button provides a single input (one increment at a time), but if you hold down either button, you can scroll much more quickly. This is really convenient when you initially set up a lot of new control inputs.

SYSTEM MENU

This transmitter has two menu systems. The first, or upper, level is called the "System Mode" and includes nine items. In this section, you can identify model-- memory positions; reset all the data to a series of factory default control inputs; and select the wing type, such as flaperons (for flap-type control with your aileron function), V-tail mixing (for roll and pitch control on a V-tail model) and delta-wing mixing (for flying tailless models such as flying wings).

You can also select the aircraft type-- either fixed wing (AC) or helicopter (HE)-and establish controls specific to each type. Although not individually called out, three programmable mixing possibilities are included, so you can tailor certain control inputs for sailplanes as well.

You can also operate the XP662 using regular FM (PPM), or you can select either of two types of PCM operation for use with compatible JR PCM receivers. When using PCM, you will also be able to program in fail-safe features. Keep in mind that when operating FM (PPM), the deviation is on the high side, so this transmitter can operate any JR FM receiver as well as most FM receivers manufactured by Airtronics. Also be aware that the XP662 transmitter does not have a removable radio-frequency module, so the operating frequency is fixed.

Another item in the "System Mode" menu is called "Dual Rate Switch Selection." With this feature, you can combine aileron and elevator dual-rate control so that it can be operated by a single switch. Many fliers like this added convenience because both controls go hand in hand.

FUNCTION MENU

The second, more detailed menu level is identified as "Function Mode," and you will probably use it more often. It contains 12 separate items (three of which are the programmable mixing circuits already mentioned). The XP662 offers not only conventional dual-rate control of both ailerons and elevator but exponential rate control of both functions as well. Exponential control tends to desensitize the controls around the neutral position. By carefully setting this feature, a "jumpy" pilot can look like a pro. Other items in the "Function Mode" menu include servo-- reversing on all six channels; endpoint or travel adjustment on all six channels; subtrim (which allows you to store the actual digital trim position in memory and then place the trim button back at zero); aileron/rudder mixing; elevator-to-flap mixing; aileron differential; and flap-to-- elevator offset trim (which allows elevator trim or compensation to be employed as the flaps are deployed to help maintain level flight).

DIGITAL TRIMS

The benefits of digital trim include more precise control application and the ability to save trim positions for each model-- memory position. On many computer transmitters that have this feature, it's difficult to know where your trim position is while you're flying. To effectively solve this, the JR engineers display the trim position on the LCD when you push the trim button. Every time you hit any of the four trim buttons, you advance the trim one increment and see something like "AIL +6." That screen will disappear in a few seconds, replaced by the "Normal Display." A little later in the flight, if you want to add more trim, hit the trim button again; you will see "AlL +8." If you use this feature to check the trim position, remember to return it to its original position; otherwise, you may constantly add or subtract trim positions during your flight. It is important to note that the XP662 automatically stores digital trims in the system memory, so you don't need to go to a secondary function, such as "Trim Offset Memory."

ADDITIONAL FEATURES

The XP662 also has a throttle-cutoff switch at the top right side of the case that automatically stops the engine; this quick, effective control is a nice safety feature.