Setting Up the JR XP9303 Computer Radio

The evolution of JR's computerized radios continues with the introduction of the new XP9303. This new radio adds some exciting features. The most interesting software upgrades are:

1. The multipoint programmable mixing has increased from 5 points to 7.
2. Many of the functions are now switch-selectable.
3. The sailplane mode has 5 selectable flight modes that can be changed during flight.
4. The radio now has side slides on both sides of the radio.
5. Motor functions can be controlled from several different switches, buttons or the throttle stick.
6. Differential now includes plus or minus functions.
7. Ailerons are now plugged into locations 1 and 2; making any four-channel receiver work with a two-aileron setup.

The XP8103 added groundbreaking multipoint programmable mixing which completely eliminates that annoying bump the model takes when you first pull the flap stick down. Landing approaches become extremely smooth. The XP9303 increases the mix from 5 points to 7, making the approach even smoother. If you don't have this feature on your current radio, this feature alone is well worth the investment.

If you've owned the JR347, the 388, or the XP8103, you will find some similarity in the programming, but the layout and location are quite a bit different. The switches are generally in the same place but the knobs have been replaced with digital trim switches.

There are three versions of the XP9303: helicopter, airplane, and sailplane. The switches are in the same place, but you now only get one manual, where you used to get all three. Fortunately, all three manuals are available online at horizonhobby.com for you to download. In addition, there is a postage prepaid request form in the box for ordering the other two manuals from JR, free of charge.

The XP9303 also sports a new and much larger screen. The new screen is nearly three times larger than that found on the XP8103 and has been moved from the top to the bottom of the radio. The screen is pixilated, allowing the computer to place a significant amount of information on the screen at one time. The larger screen also contains an X\Y axis graph that is designed to visually represent dual rates, exponential rates, and the multipoint programmable mixing.

The new XP9303 supports a case significantly different than prior radios. The new radio still fits my hands better than any radio I have ever held. Some of the additional changes to the case include:

1. Only four buttons instead of eight. A new scroll wheel has been added to make scrolling through all the possible selections even easier. When you find the correct selection, just push to click the scroll wheel.
3. Side slides on both sides of the radio have been added.
4. Rubber grips on the sides and a much deeper recess on the back for your fingers for a much more relaxed fit in your hands.
5. The transmitter module is much easier to remove and prior transmitter modules are still usable.
6. The front knobs have been replaced with a digital trim switch.
7. The butterfly switch has been replaced with a push-button toggle switch.
8. Newly molded stick ends that keep fingers from slipping off.

The XP9303's transmitter modules are interchangeable with all other JR® radio modules.

Flash memory is used for saving all the settings. No more internal battery to be replaced every few years or so.

The sailplane version comes with three digital 386 servos (I have been using these servos for about a year and they are hot!) and the new slim line seven-channel receiver. The new R770 receiver is a high performance PCM single conversion receiver with the new 10KHz narrow band ABC&W circuitry. This new receiver is half the size and weight of the previous credit card style receiver.

Digital trims were introduced with the 8103 and when you have a radio with multiple model memory, it is the only way to go. You no longer have to save your trim settings before you switch to a different model in the radio. As you switch from model to model, the radio automatically remembers the last trim setting of each model. If you fly two classes in your local competitions, you no longer have to swear at yourself for forgetting to save your last trim locations. No more sub-par launches when you forget to reset the trim lever to neutral before launching a different model.

To change the trims, you simply bump the trim lever. Each time you bump the trim lever there is a corresponding change in the position of the control surface on the aircraft. A black dot moves along the graphic bar on the display screen and the radio makes a beep each time you bump the lever. If you bump the lever and hold it down, the trim will make rapid advancement in the direction the lever is held. As the trim is changed to the top or to the right, the beeps become come higher in pitch. As the trim is changed to the left or bottom, the beeps become lower in pitch. As the trim passes through the center position, a louder, more easily recognizable beep occurs.

On the surface, digital trims do not sound like much of an improvement. Boy, what a surprise! The resolution of the digital trims is adjustable in the TRIM STEP mode. In its default mode, one click of the digital trim is approximately the same as the old style trims. The default can be changed so that it takes 3 or 4 clicks of the digital trim to equal one click with the old style trims. With the digital trim's finer resolution, the elevator "sweet spot" is much easier to find. Whether the resolution is fine or coarse, the total amount of trim adjustment remains the same (approximately 15 degrees each way from center).

Over the last ten years or so, there has been a significant amount of discussion concerning elevator "dead band." "Dead band" may appear in several forms or any combination of forms. The most common is lack of pitch change with small stick changes near center. Another is a plane that cannot hunt. In other words, upon moving to level flight, the aircraft feels like it's mushing along (nose high). The next time the aircraft moves to level flight, it feels like it will not slow down (nose down). It seems to occur most often on aircraft with full flying stabs.

There are many items that can contribute to "dead band." The ones most often discussed are sloppy linkages, poor choice of stabilizer airfoil cross-section, and worn out servo pots. Lack of trim resolution in the radio adds a new "dead band" contributor to the discussion. With a trim step resolution of only 1 or 2, dead band has all but disappeared.

JR® has brought flexibility to a new level on the XP9303 by adding assignable switches, slides and sticks. For all you guys that have been demanding assignable switch locations, we hope you won't complain about the added complexity of radio programming.

Flight Modes are the newest wrinkle in computer radios. Another manufacturer has a radio that allows an alternative setup that can be changed in flight. The XP9303 has five Flight Modes that can be changed in flight with the simple flip of a switch.

Cruise is the default flight mode. The other flight modes are inhibited when the radio is first turned on. The XP9303 in this form has more power (side slides) than the XP8103, but not much. It is the power of the Flight Modes that make this radio really something. Each of the 5 flight modes (Launch, Cruise, Land, Speed and Thermal) can be easily selected in flight. Each Flight Mode allows you to program each of the following mixes separately: Dual Rate and Expo, Elevator-to-Flap, Aileron-to-Flap, Differential, FM Delay, Flaperon Mix, Aileron-to-Rudder mix, Butterfly, Flap Rate, and each of the non-dedicated mixes.

In addition, you can set the radio so that each trim (Aileron, Elevator, Rudder, Flap and Flaperon) is the same for each Flight Mode or separate for each Flight Mode. As an example, elevator trim can be set so changing the trim in one flight mode will change it in all the remaining modes also. Alternatively, you can set the radio so that the trim settings for each flight mode have no effect on other flight modes.

A practical application would be for different elevator trims in different flight modes. Start by flying and trimming the plane in COM (common) mode. In COM mode, elevator trim for all five flight modes has a common starting point. Once accomplished, switch to FM (Flight Mode) mode. You might want a couple click of up trim in launch and thermal mode, and a couple of clicks of down trim in speed and landing. Now, when you switch from Flight Mode to Flight Mode, the trims change automatically. Pretty cool. (In the following instruction sets, there is no reminder to switch to FM mode AFTER the initial trims have been established.)

In addition, the radio can be set to transition slowly from one mode to another to reduce the suddenness of changing from one flight mode to another if there are significant trim differences.

The trainer function instructions are now written right into the radio screen. The trainer function allows you to select the servos in the airplane that the trainee is controlling. In other words, you can selectively allow them to learn elevator first, then add rudder second, etc.

One feature that you are not going to discover is an adjustable screen contrast. Although available on the XP8103, it is not present on the XP9303.

The XP9303 allows you to transfer all the trim settings directly into another XP9303 through a trainer cord. You may not transfer trim settings from any radio other than another XP9303. Several mix values changed in the radio, making them incompatible for transfer through the trainer cord. A good description of how to make this function work can be found in the airplane manual.

Over the years, there have been a lot of complaints about the lack of an "OFF" setting in computer radios. Most computer radios do not contain a setting called "OFF." Why? Because every function is "ON" all the time. As long as the mix value is set to -0-, nothing will happen. In other words, "OFF" and "-0-" are the same thing.

The sailplane channel assignments with the 9303 have changed from prior radios. These new assignments are for all receivers (prior JR® and other brands). The new servo assignments are:

Channel Assignments

JR claims this new channel assignment allows for better communication between the radio and the sailplane. What it really means is that a six-channel receiver will now work with a six-servo sailplane. All prior radios with JR setups would have required a seven-channel receiver.

The motor assignment for a four-servo setup defaults to channel #5. When dual flaps are activated, the motor assignment defaults to channel #7 (AUX2). However, these defaults are easily changed.

The battery may be plugged into any empty slot on the receiver or Y-harnessed if necessary. The new 770 receiver packaged with the radio is a seven-channel receiver with an eighth dedicated battery slot.

Programming Review
Flexibility is a wonderful thing. However, programming the JR XP9303 is complicated by the fact that the radio's flexibility may provide more than one way to accomplish the same result. Although more than one means may be available, it is important to select and use only one method to accomplish your objective. Otherwise, programming functions may be in conflict and actually cancel themselves out. This article is only one of the many methods to accomplish the objectives below. If you disagree with my methods, or have found something that works better, please let me know what it is for use in a future article.

This article also assumes that you own an XP9303, have the manual handy and are familiar with the four programming buttons across the face of the radio and the selector wheel. The page numbers referenced in the article are the page numbers found in the manual.

This manual provides the setup for several different types of sailplanes. The purpose is to show just how similar the programming is for each type of sailplane. You don't have to relearn the programming for a different model.

The transmitter has two separate programming modes. These are the system setup mode and the function mode. The system setup mode comes at the beginning of the instruction manual (Page S2) and must be completed before you perform any of the function modes. (Page S15) If you program the function settings first, and then revise the system setup settings second, it may result in wiping out your programming and returning to the system defaults.

Recommended Changes to the Manual
Page G9 contains the image of the front of the radio. Modify or make the following additions to this page and it will make your programming easier.

The following receiver channels can be assigned to any one of following switches, levers or sticks. This explains why the image of the radio seems to be missing some information:

Switch Assignments

The following actions can be assigned to any one of the following switches, levers or sticks.

Timer can be assigned to any of the following:
Ail D/r
Ele D/R
Rud D/R
Aux4 SW
Time SW
BTFL SW
Tim Key

Launch, Cruise, and Land Flight Mode can be assigned to any of the following switches. To put Launch, Cruise and Land on one switch would require a three-position switch. There are only two three-position switches and they are labeled R3P SW and L3P SW. (right and left three-position switch). If you choose to assign a flight mode to a two-position switch, the radio automatically selects the middle and upper positions and discards the lower position. As an example, if you choose the AIL D/R for your Launch, Cruise, Land Flight Mode, only Launch and Cruise are available as Flight Modes. The radio will automatically recognize this and whenever you come to a screen showing the available Flight Modes for mixing, Land will be missing.
INH
AIL D/R
ELE D/R
RUD D/R
AUX4 SW
R3P SW
L3P SW
BTFL SW

Speed, Thermal Flight Mode can be assigned to any of the following:
INH
R3P SW
L3P SW

The non-dedicated mixes can be turned on or off by selecting a flight mode or switch on the radio. Also, a non-dedicated mix can be activated by more than one switch or any combination of switches. This may look simple, but it can become complicated. AX4 and BTF are fixed switches. However, CRU, LAU, LAN, SPD, and THM are Flight Modes that can be assigned to any switch identified above.

Non-dedicated mixes 3 through 6 are activated by the following switches:
CRU
LAU
LAN
SPD
THM
AX4
BTF

The following switches activate non-dedicated mixes 1 and 2:
ON
CRU
SPD
THM
LAU
LND
AX4
BTF

More Recommended Manual Changes

Now that you have all the flexibility figured out, the following modifications to the manual are still recommended:

1. Page S2. On the diagram for [Device. SEL] insert the following under SPEED INH "TRIM:COM". TRIM:COM only appears on the screen when either or both of the flight modes are activated. COM (Common Mode) can be changed to FM (Flight Mode). This same change should be made on page S9, S11, S12, S13 and page S46. This allows trim to remain unchanged from Flight Mode to Flight Mode. Switching to FM means that each Flight Mode has its own trim settings. If trims are set to FM mode, be especially careful during the first flight to remember that the aircraft will need to be trimmed using the digital trims for Aileron, Elevator and Rudder for each Flight Mode selected during flight. If the aircraft is badly out of trim in one Flight Mode, it will probably be badly out of trim for each Flight Mode selected. Leave this condition set to COM for the first flight so trims are set for each Flight Mode. Only after trimming the aircraft, then go back into [Device. SEL] and change COM to FM. Now you can change trims for each Flight Mode with each Flight Mode starting from the same base line.

2. Page S15. Delete CAMBER ADJ and replace it with FM Delay. (also page S55, S60 & S66) Delete CAMBER MIX and replace it with FLAPRN MX. (also page S55, S61 & S67) The function list also contains MOTO.HOLD. MOTO.HOLD is only visible on [FUNC. LIST] if MOTO is ACT on the DeviceSEL menu.

3. Page S17. There is a missing screen. On the MONITOR screen, scroll the curser over MONI and click the rolling selector. You will see the screen on page S39 and S51 entitled CAMB.

4. Page S18. There should be another screen here. If you continue to scroll the cursor to the right, the X-Y graph will disappear to be replaced with any flight modes that have been activated. You can change the D/R and EXP for each flight mode by assigning a flight mode to one of the three rates. These assignable values only appear if flight modes are activated.

5. Page S18. The F.M.O on the D/R & EXP should be replaced with Pos-0. The same with F.M.1 and F.M. 2.

6. Page S24. Change the title of the page and the screen name from CAMBER ADJ to FM Delay.

7. Page S25. Change the title of the page and screen name from CAMBER MIX to Flaprn MX.

8. Page S28. The phrase "camber mix" is used in the first sentence. Unfortunately, DeviceSEL in the service menu does not contain a "camber mix." The DeviceSEL screen uses the word "FLAP". Confusing, but they mean the same thing.

9. Page S29. This function is only available when MOTO is ACT on the DeviceSEL menu.

10. Page S31. On the far right of the screen image, the words TIM KEY appear. I still have not been able to identify what the TIM KEY is.

11. On several screens, the instructions are discussing a setup in launch mode, but the screen fails to include a launch Flight Mode.

By now, you are probably wondering what you have gotten yourself into. Don't worry, you're going to love it.