Power Switch: JR 12X 2.4 GHz RC System - 2009/03

Power Switch: JR 12X 2.4 GHz RC System

Frank Granelli

For many years, JR has had one of the best advanced radio-control systems: its sophisticated 10X transmitter and various matching 10-channel Pulse Code Modulation (PCM) receivers. The combination has proven itself as a reliable competition and scale performer. Thousands of competitive pilots who regularly experience tense situations rely on their 10Xs.

As good as the 10X is, it has two shortcomings. First, scale pilots can always use more channels as their superb models get ever more complicated—ten channels doesn't seem enough. Second, the 10X is unavailable in a 2.4 GHz system.

A "2.4 GHz" designation means the radio system transmits digitally on the 2.4 GHz band instead of the 72 MHz band. Because of FCC regulations and the way the technology works, it is extremely difficult for one 2.4 GHz system to interfere with another. JR goes even further to prevent interference by randomly selecting two frequency bands (called "DuaLink") within the 2.4 GHz space for each flight.

If you have spent thousands on a model or invested hundreds of hours in a scale masterpiece, having such "shootdown" protection is comforting. Even noncompetition pilots need 2.4 GHz.

Enter the 12X. Operating on 2.4 GHz has several other advantages, including speed and digital precision—both vital for competition pilots. Rather than simply converting the 10X to 2.4 GHz, JR developed a new system with more channels, greater flexibility, and easier programming.

The sophisticated 12X DSM2 radio system is designed for the advanced modeler. It can be ordered as either a 2.4 GHz-only system (compatible with all Spektrum and JR 2.4 GHz receivers, even the first AR6000) or as a selectable 2.4 GHz/72 MHz system: the JR12X MV.

Key capabilities and hardware

• 50-model internal memory (accepts unlimited model memories from a computer, 50 at a time).
• ModelMatch: aircraft respond only if the exact receiver/aircraft is selected on the transmitter.
• Optimized programming for airplane, helicopter, and soaring operation—each category has dedicated features.
• Triple rate/exponential switches, five flight modes, and dual snap-roll switches positioned to keep both hands on the sticks while pushing the button.
• Double flight-battery inputs and a receiver that can handle up to 35 amps of current.
• Two fail-safe systems and four separate receivers (the R1221 main unit plus three satellites) for maximum reception redundancy.
• 2048-resolution and fast response on all channels (2,048 discrete servo positions across the servo output arc).
• Extremely low latency for faster stick-to-servo response.
• Knife-edge trimming, twin-engine mixing, and servo synchronization with no extra equipment.
• Manual throttle-trim lever provides easy in-flight adjustment for high-trim aerobatics, medium trim for approaches, and engine shutoff (low) on one lever.
• No throttle ratchets (indents) by default; JR will install throttle detents free on request.
• Includes an Applications and Programming Guide in addition to the detailed instruction book.

Performance: speed, resolution, and servos First, the 2.4 GHz 12X is faster than a PCM system. PCM requires several analog-to-digital transformations; the 12X transmits digitally, eliminating those translation phases and resulting in a much shorter latency period. Advanced servos are so fast (0.06–0.15 second) that any latency is noticeable—so the reduced latency is a real advantage.

Second, the 12X's 2048 resolution provides extreme precision and ultimate aircraft control. Most sport 2.4 GHz radios are 1024 systems—half as exact. The high resolution is especially valuable for IMAC competition, Pattern, F3C, and 3-D helicopters.

You should employ digital servos to get the full benefit of 2048 resolution because they are more precise than analog servos. All 12 channels are 2048 resolution and are equally fast and proportional. There is no closer bond between pilot and model than with a 2048, low-latency, 2.4 GHz system such as the 12X—the pilot's "feel" is immediate. Many competition pilots add extra exponential points until they become accustomed to the enhanced control. Throttle response in particular is faster and more controllable; stall turns and snap rolls become easier to time correctly.

Programming simplicity and unique features The 12X is notable for programming simplicity. As with all JR systems, programming is divided into two stages: System and Function modes.

• System Mode: covers operations usually set once—selecting aircraft, determining type (airplane/helicopter/glider), naming it, setting wing type, switch responsibilities, etc. All paradigms appear at once on the screen—no paging and scrolling—so you roll the button to highlight and press to enter.
• Function Mode: frequent changes (knife-edge trim, subtrim, exponential, aileron-rudder mixing, step-mixing, programmable mixing, etc.) appear on one page via the "LIST" button; roll, highlight, and press.

Unique programming and practical features

• Knife-edge trim page mixes rudder to both aileron and elevator in one mix.
• Dual elevator servos can be mixed from a single page, including in-flight trim changes.
• Balance function combined with servo speed adjustment matches servo movement and speed so multiple servos moving a single control surface operate identically.
• Balance function (a curve mix) adjusts for separate elevator half geometries, assuring equal elevator response.
• Main control sticks can be used as mixing on/off switches (useful for smoke-system setups and more).
• Five curve mixes and five Flight Modes—not just three—are available.
• Flight Modes let one airplane have multiple trim/program settings (examples: different propellers, wind conditions, 3-D vs. sport settings, scale slow-pass configurations).
• The Snap Roll button and additional Flight Modes allow quick setup for maneuvers requiring different control responses or snap directions.
• Knife-edge mix can be switched by the throttle stick so trim settings operate during flight but are inhibited during stall turns and landings.
• Throttle-stick position can alter programmed aileron differential rate to compensate for changing yaw/adverse yaw with airspeed.
• Twin-engine mix ensures both engines operate at the same RPM across the throttle range, eliminating normal twin yaw effects.
• Throttle trim lever can control both engines simultaneously or provide independent trim levers for each engine (useful for single-engine practice).
• Two trim settings: standard trim (center point and endpoint movement, adjustable coarse-to-fine) and LST (Limited Standard Trim), which adjusts only the center point to prevent overdriving servos at endpoints. Digital trim can apply to one Flight Mode or be common to all.
• Dual Channel function powers control surfaces with separate servos while remaining responsive to single digital trim buttons—great for independent elevator halves or ailerons.
• Trim system includes digital button trims for flight control surfaces and a throttle trim lever (eliminates need for a separate engine kill switch).
• Two switchable aileron differential settings per Flight Mode.
• Elevator-to-flap and flap-to-elevator mixes compensate for pitch changes caused by flaps; flap timing can be set in 0.1-second intervals so both surfaces move at the same speed. The Auto Land feature can manage this automatically.
• Mix monitor displays all programmed mixes, dual channels, selected switches, and control surfaces for a one-glance view of the aircraft setup.
• Software and connection hardware included to copy programs to/from another 12X or a computer.
• All trim screens have throttle and/or servo "hold" settings that make safe throttle-based trim changes possible while the power system is operating.

JR12X Notable Features

Airplane Standard

• Servo reverse
• Travel adjust
• Exponential
• Subtrim
• Throttle hold
• Throttle curve
• Servo speed
• Snap roll
• Aileron differential
• Aileron-to-rudder mix
• Elevator-to-flap mix
• Flap-to-elevator mix (flap system)
• Eight programmable mixes (five curved)
• Flaperon, V-tail, and elevon mixing

Airplane Advanced

• Servo balance
• Triple rates (aileron/elevator/rudder)
• Knife-edge mix
• Five flight modes
• Twin-engine mix
• Control stick as mix switch
• Pitch curve (adjustable propellers)
• Aileron-to-flap mix
• Internal model memory backup copy system
• Plus additional advanced options

Helicopter Program Features

• Six swashplate types (normal; two-servo 180°; three-servo 120°, 140°, and 90°; four-servo 90°)
• Programmable trainer system (selectable channels for student control)
• Gyro sensor support
• Servo speed and governor control
• Tail curve and dual pitch
• Swashplate mix and pitch curve
• Eight programmable mixes
• Built-in cyclic-to-throttle mixing for aileron, elevator, rudder
• Electronic 3-D cyclic ring to prevent overdriving cyclic servos with combined aileron and elevator commands
• Programmable servo speed

Sailplane Program Features

• Ability to assign switches for channels and functions
• Rudder-to-spoiler mix and aileron-to-rudder mix
• Flap rate and brake system
• Eight program mixes (five curved)
• Trim system adjustment and as many as five fully programmable, nameable Flight Modes
• Tip aileron programming and fully programmable motor function
• Camber programming for each Flight Mode
• Servo monitor that automatically renames channels according to assignments
• Warning system with custom-programmable alarms for various switch and stick positions

Receiver and hardware details The included JR R1221 receiver is actually four receivers: the main unit plus three satellite receivers that mount remotely at 9, 12, and 24 inches from the main receiver to ensure the strongest possible reception in all flight attitudes. The R1221 has full 2048 resolution plus dual flight-battery inputs for greater safety.

Documentation and support The system arrives with a detailed instruction book and an Applications and Programming Guide. The step-by-step manual covers setup and programming of a complex Giant Scale IMAC airplane, a competition helicopter, and a complex sailplane. The sailplane guide covers Cruise Mode, camber adjustments, airborne braking systems, launch and landing modes, and other soaring-specific items. The helicopter guide covers swashplate mixing, cyclic mixes, throttle and pitch curves, throttle holds, and trimming operations. Jet pilots will appreciate the extra Flight Modes and the "stick as switch" options.

Minor imperfection The 12X is available only without the usual throttle-stick indentations ("throttle clicks"). According to JR, that was a request from helicopter and scale aerobatics team pilots. JR will install throttle detents free for any pilot who wants them.

Conclusion Although this report has probably missed a dozen important 12X capabilities, the JR 12X leads the pilot to growth: more channels, higher resolution, faster response, and programming versatility. It is optimized for today's complex scale, competition, and advanced sport aircraft and represents the only transmitter many pilots will ever need.

Frank Granelli [email protected]

Sources:

• Horizon Hobby Distributors, (800) 338-4639, www.jrradios.com

Other Printed Reviews:

• Model Airplane News: November 2008

Transcribed from original scans by AI. Minor OCR errors may remain.