T8FB(OTG) User Manual(in PDF)

Online Manual Contents




① Never operate your model during adverse weather conditions. Poor visibility can cause disorientation and loss of control of your model.

② Never use this product in a crowd and illegal area.

③ Always ensure the trim levers at 0 and battery properly charged before connecting the receiver.

④ Always check all servos and their connections prior to each run.

⑤ Always be sure about turning off the receiver before the transmitter.



This product is not a toy and is NOT suitable for children under the age of 18. Adults should keep the product out of the reach of children and exercise caution when operating this product in the presence of children.

Water or moisture may enter the transmitter inside through gaps in the antenna or joystick and cause model instability, even out of control. If running in the wet weather (such as game) is inevitable, always use plastic bags or waterproof cloth to cover the transmitter.

This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:

  • This device may not cause harmful interference, and
  • This device must accept any interference received, including interference that may cause undesired operation.

Any Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.








① One two-way switch, one three-way switch, two VR switches, four trimmers, two sticks.

② The picture below is mode1, SwB is default to control CH5, VrB is default to control CH6, SwA is default to control CH7 and VrA is default to control CH8.

③ Universal JST battery connector supports multiple batteries, include 4pcs AA batteries or 2S to 4S LiPo battery.

④ Defaulted low battery alarm voltage can automatically match 2S and 3S LiPo battery or 4pcs AA batteries, can setting in the T8FB configure software.

3S LiPo battery: default low voltage alarm to 11.0V automatically after detection, you can setup low battery voltage alarm from 10.0V to 12.5V.

2S LiPo battery: default low voltage alarm to 7.3V automatically after detection, you can setup low battery voltage alarm from 7.0V to 8.9V.

4 pcs AA Ni-MH battery: default low voltage alarm to 5.0V automatically after detection, you can setup low battery voltage alarm from 4.0V to 6.4V.





Prepare before Use


① Make certain the alignment tab on the battery, switch and servo connectors is orient correctly and ‘key’ into the corresponding notch in the receiver or connectors before plugging them in. When unplugging connectors, never pull on the wires. Always pull on the plastic connector instead.

② Receiver’s Antenna: In generally receiver’s antenna is longer than remote control, don’t break or retract it, otherwise shorten the control distance. The antenna must be kept away from conductive materials, such as metal. Please make distance test before flying.

③ If your aileron servos are too far away to plug into the receiver, use an aileron extension cord to extend the length. Avoid plugging multiple extensions together to obtain your desired length. If the distance is greater than 50cm or high current draw servos are being used, use heavy servo extensions.

④ Receiver Vibration and Waterproofing: the receiver contains precision electronic part. Be sure to avoid vibration, shock, and temperature extremes. For protection, wrap the receiver in foam rubber or other vibration-absorbing materials. It is also a good idea to waterproof the receiver by placing it in a plastic bag and securing the open end of the bag with a rubber band before wrapping it with foam rubber. If you accidentally get moisture or fuel inside the receiver, you may experience intermittent operation or a crash. If in doubt, please contact Radiolink after-sales or distributors for service.

⑤ Always mount the servos with the supplied rubber grommets. Don’t over tighten the screws. No part of the servo casing should contact the mounting rails, servo tray or any part of structure. Otherwise vibration will be transmitted to the servo causing damage of servo. Note the small numbers (1,2,3,4) molded into each arm on the servo arms. The number indicate how many degrees each arm is ‘off’ from 90 degrees to correct for minute manufacturing deviations from servo to servo.



⑥ To center the servos, connect them to receiver and turn on the transmitter and receiver. Center the trims on the transmitter, then find the arm that will be perpendicular to the push rod when placed on the servo.




⑦ After the servos are installed, operate each servo over its full travel and check that the push rods and servo arms don’t bind or contact each other. Also make sure the controls do not require excess force to operate. If there is an objectionable buzzing sound coming from a servo, there is probably too much resistance in the control. Find and correct the problem. Even there is no servo damage, excess battery drain will result.

⑧ Use the mouthing plate from the receiver on/off switch as a template for the cutout and screw holes, mount the switch on the side of the fuselage opposite the engine exhaust, and where it won’t be inadvertently turned on or off during handling or storage. Be certain the switch moves without restriction and ‘snaps’ from ON to OFF, and that the cutout allows full motion of the switch in both directions.

⑨ When install the switch harness to the helicopter, please use the switch cover. Generally, sandwich the frame between the switch and switch cover and securely tighten the screws. Different models might require different installations. If so, please follow the model’s instruction manual.

⑩ To prevent the servo lead wires from being broken by vibration during flight, provide a slight amount of slack or extra so that the wire sticks out slightly and fasten it at suitable points. In addition, periodically check the wire during daily maintenance.






Radiolink T8FB is comes with an 8 channels receiver R8EF. R8EF is support S-BUS, PPM and PWM signal working at the same time.


① Channels: 8 channels

② Working voltage: 4.8-10V

③ Working current: 30mA(input voltage:5V)

④ Size: 48.5*21*11mm

⑤ Weight: 7g

⑥ 4096 section precision, 0.5us per section, servo anti-shake rudder.

⑦ Control distance: about 500m ground and 1000m air, actually control distance depends on the environment.




Receiver Bind


① Put the transmitter and the receiver close to each other within 50 centimeters.

② Power on T8FB and receiver R8EF (or R8FM/R8SM).

③ There is a black binding button (ID SET) on the side of receiver. Press the button for more than 1 second and release, the LED of receiver will flash quickly, meaning binding process is ongoing.

④ When the LED stops flashing and is always on, binding is complete.

⑤ Make sure servos connected with the receiver can be operated by the transmitter.




Signal Working Mode


(1) PWM Working Mode

Receiver indicator is RED with all 8 channels output PWM signal.



(2) SBUS/PPM Working Mode

Receiver indicator is Blue (Purple) with 8 channels output in total. Channel 1 is SBUS signal, channel 2 PPM signal and channel 3 to 8 PWM signal.




S-BUS&PPM and PWM signal change

Short press the ID SET on the receiver twice within 1s to switch the SBUS/PPM signal to PWM signal. When the RED LED is on, signal output is PWM. When both RED and BLUE LEDs are on. Signal output is SBUS&PPM.


MINI Receiver

T8FB is also compatible with 2.4G 8 channels supper mini receiver R8SM and R8FM, which support S-BUS and PPM signal working at the same time, supper mini size, is designed for racing drone.




Note of receiver usage


① Keep antennas as straight as possible, or the effective control range will reduce.

② Big models may contain metal parts that influence signal emission. In this case. antennas should be positioned at both sides of the model to ensure the best signal status in all circumstances.

③ Antennas should be kept away from metal conductor and carbon fiber at least half inch away and no over bending.

④ Keep antennas away from motor, ESC or other possible interference sources.

⑤ Sponge or foam material is advised to use to prevent vibration when installing receiver.

⑥ Receiver contains some electronic components of high-precision. Be careful to avoid strong vibration and high temperature.

⑦ Special vibration-proof material for R/C like foam or rubber cloth is used to pack to protect receiver. Keeping the receiver in a well-sealed plastic bag can avoid humidity and dust, which would possibly make the receiver out of control.





Transmitter Calibration


Press rudder trimmer left and turn on transmitter at the same time,

When the transmitter is power-off, toggle both sticks at the central point. Then press the rudder trimmer button left and the power button simultaneously, red and green LED will start flashing and the T8FB is ready to be calibrated.



Range Calibration

Toggle both sticks (Ch1-4) to the highest point/maximum and the lowest point/minimum. Then back to the central point. (Refer to image below)




Center Position Calibration


Put stick to the center position, press rudder trimmer right, and then red and green LED always on means sticks calibrate successful.




Firmware Upgrade


Connect T8FB to a computer with an android USB cable, then setup parameters as you need.

Upgrade firmware by a USB cable helps T8FB always keeps the most advanced system and program. The USB data backup copy function of T8FB helps save and copy parameter settings easily.





Firmware Introduction


The latest firmware is V301.

We will upgrade firmware according to T8FB users, new firmware will not upgrade in this manual, you can download it from our website: www.radiolink.com




Upgrade Steps


① Download the divers that T8FB upgrade need from our website: https://www.radiolink.com/t8fb_firmwares

② Open file “T8FB”.



③ Choose COM, and click “Connect” and then turn on T8FB in 1 second.

④“Disconnect” will change to “Connected” and the color of word will from red to green if connect successfully.




⑤ Choose “APROM” and then choose the firmware V301



⑥ Click “Start”, the progress bar will turn to green, upgrade successful if remind “PASS”.






T8FB Parameters Setup


Android APP


New version T8FB that with USB upgrade port will support parameters setup via android smart-phone APP.






① One USB cable for Android smart-phone

The smaller port connects to T8FB USB port and the other bigger port connect to OTG data cable.

② One OTG cable for Android smart-phone

The smaller port connects to smart-phone USB port

③ Android smart-phone system requires to upgrade to version 4.0 or above.

Attention: This APP do not support iPhone now.




APP Installation


① Download the “RadiolinkT8FB (en).APK” software to your phone (please download from our website www.radiolink.com, click the software to install, or scan this QR code to download.

② Click “Done” when APP have installed, you will see the T8FB parameter setting APP on smart-phone interface, if you click “open “, the APP will open directly.

③ You can find out the installation steps as below





Connection Steps


① Turn on the transmitter T8FB at first.

② Connect USB cable to your phone after installed the APP, it will hint if open “Radiolink T8FB” when connection.

Attention: Different smart-phone (as OPPO R9s and so on), you have to turn on the OTG connection first (settings - Other settings - OTG Connection)

T8FB will come with a OTG cable, please make sure the smaller port of OTG cable connect to Android smart-phone. Connect your T8FB and your Android smart-phone as this picture:




When the APP is installed and cables between T8FB and android phone are connected correctly, a notice will pop out to ask if ok to open the app. Click yes then the APP interface will pop out and displayed as below.






The Functions Introduction


1) there are four interfaces in total,” SERVO”,” BACIS”,” ADVANCED”,” SYSTEM”

2) Every interface will show the voltage of T8FB.

3) Change to the function interface you need by click the corresponding button.

4) Click the “CONNECT” to setup parameters and “DISCONNECT” or  “CLOSE” button to quit setting.





Setting Buttons Introduction


(DIS)CONNECT: When APP is opened on the mobile, T8FB will be connected automatically. If can’t be identified, click DISCONNECT then CONNECT again.

READ: Click READ, the APP will start reading the data in T8FB, the process won’t complete until 4 D sounds are heard. Every time reopen the APP, the data displayed are default. If any parameter is changed, it can’t be displayed until clicking READ.

UPDATE: Click to update the changed data into the T8FB and a D sound means update complete. If no D sound means update failure. Click UPDATE each time parameter is modified.

SAVE: Click to save the APP data in the /model/model01.text in the mobile and APP will automatically create a model01. txt file.

LOAD: Click LOAD and the APP will take the data from /model/model01.txt. APP will notify if this file can’t be found.

CLOSE: Click Close to exit.

Note There is T8FB(T8FB) voltage displaying on each menu.


Parameters Setting Steps

① When parameters need to be modified, click READ first to input the original data into the software, then modify as wish and click UPDATE to output the modified data to T8FB.

② When parameters SAVE as TXT file need to be input, click LOAD first to input the saved data into the software then click UPDATE to copy them to T8FB.





Four Interface Introduction


1)” SERVO”: The 8 rectangles show the CH1-CH8 servos range (4 basic channels and 4 auxiliary channel) from left to right.





2)” BASIC”: There are six parameters to setup including” REV” “SUB” “EPA-L” “EPA-R” “F/S” “DELAY”



REV: Defines the relationship between the transmitter controls and the receiver output for channels with options of NORM and REV. Make sure to check all servos move to the correct direction as wish under control. Make sure to check all servos move to the correct direction under control.


SUB: Makes small changes or corrections to the neutral position of each servo. The default is 0 setting by factory setting. That is, no SUB-TRIM. The range is from -120 to +120 and can be modified with actual need.

It’s advised to center the digital trims before making SUB-TRIM changes, and keep all of the SUB-TRIM values as small as possible. In order to restrict the servo travel range, the recommended procedure is as follows:

Measure and record the desired surface position;

Zero out the SUB-TRIM;

Mount servo arms and linkages so that the control surface’s neutral is as correct as possible;

Modify with SUB-TRIM small range value to make fine corrections.


EPA-L &EPA-R: Sets the range of each channel in percentage. The most flexible version of travel adjustment is available. It independently adjusts each end of each individual servo’s travel, rather than one setting for the servo affecting both directions. The default value is 96.


F/S: Sets responsive action of model in case of signal loss or low Rx voltage (in percentage).

Each channel can be set independently. 

The NOR (normal) setting holds the servo in its last commanded position.

The F/S (Fail Safe) function moves each servo to a predetermined position.



The setting of the throttle F/S also applies to the low battery voltage. F/S value 0 means throttle stick at the lowest point while 50 means at the central point.

The F/S function is used in certain competitions to ensure safety landing of the model prior to flying away and dropping. Conversely, it can also be used make all servos neutral to maximize the flight time.


DELAY: Adjusts the synchronous ratio between the servos position and the actual operation. The default value is 100 by factory setting meaning no delay.


 3)” ADVANCED”: There are four parameters to setup:” D/R” “ATTITUDE” “ELEVON” “V-TAIL”



D/R: Sets the auxiliary switch to control the max and min values of corresponding channel range. Turn on “MIX” (mix control) first and choose an auxiliary switch to flip and set the max/min range value to its corresponding channel by toggling. In the example picture shown above: When flip SWA upward and toggle CH1 stick, it means the max/min range of CH1 can be +100 and -100. If the UP value modified to 50, it means the max range can only be +50/-50 when toggle CH1 up and down. ‘DOWN” means when flip SWA downward, the max/min value of CH1 is +100/-100.


ATTITUDE: Turn on “CH” first and select the preferred channel. The values behind each channel means different control percentage output different control signals.

Pilots can set 6 different modes (NORMAL, ATTI, GPS, HOVER, F/S and AUX) by adjusting the related rates. Every mode has different rates to get a unique signal. NORMAL mode preset 0%, ATTI 50%, GPS 100%, HOVER 25%, F/S 75% and AUX 50%. 0% means a output signal 1ms, and 100% means 2ms.

Note If flight controller used is RadioLink PIX or Mini Pix, no setup needed here by default.


ELEVON: Turn on “MIX” (mix control) first, adjust the aileron distance and allow aileron differential.


CH1 and CH2 are required.

Independently adjustable aileron travel allows aileron differential.

Independently adjustable elevator travel allows for differences in up vs. down travel.

The separate ELEVON settings for each condition can be set. (GLIDER only)


V-TAIL: This function is used on the V-tail aircraft.

V-TAIL mixing is used with v-tail aircraft so that both elevator and rudder functions are combined for the two tail surfaces. Both elevator and rudder travel can be adjusted independently on each surface.


CH2 and CH4 are required.

Independently adjustable travel allows for differences in servo travels.

Rudder differential is not available. To create rudder differential, set RUD1 and 2 to 0, then use two programmable mixes, RUD-ELE and RUD-RUD, setting different percentages for up and down. These are new rudder travels. Turn the trim and link off, switch assignment null so rudder won’t be accidentally turned off.


V-TAIL function and ELEVON/AILEVATOR mix functions can’t be activated at the same time. If both of these functions are activated, an error message will be displayed and you must inactivate the last function prior to activating ELEVON.

Make sure to move the elevator and rudder sticks regularly while checking the servo motions. If a large travel value is set, when the sticks are moved at the same time, the controls may mutually disturb or run out of travel. Decrease the travel until no disturbance occurs.


4) “SYSTEM”: There are three parameters to set: “AUX-CH” “PROG.MIX1” “PROG.MIX2”




CH5/6/7/8 Auxiliary channels Ch5 to Ch8 can be personalized to different switches

TX Alarm

When the transmitter voltage is lower than the value set, T8FB will make D sound to warn.

STK-MODE by default

 1 is throttle at right while 2 is throttle at left. 3 is throttle at right for toys while 4 is throttle at left for toys.

VERSION: The numbers mean different firmware versions which can be updated. 



Programmable mix controls are to

Diversify attitude changes of aircraft (e.g. Rolling to realize when rudder is commanded);

Control a certain axis with two or more servos (e.g. 2 rudder servos);

Correct special movement automatically (e.g. Lower FLAP and ELEVATOR servos at the same time);

Control the second channel to respond to the movement of the first channel (e.g. Increase smoke oil to respond to high speed, but only when the smoke switch is activated).;

Turn off the main control under certain circumstances (e.g. For dual-engine aircraft, turn off a motor or speed up/down one motor to assist rudder to turn)


PROG. MIX1: the mix control of AILERON and ELEVATOR servos is to assist turning.

PROG. MIX2: the mix control of ELEVATOR and FLAP servos is to loop in small diameter.

Adjustability: Channel 1 to 8 can be personalized to mix.

MAS: Master channel. Other channels need to cooperate with movements of the master channels.

SLA: Slave channel. Many mix controls are controlled by one master channel. e.g. Rudder-Aileron mix control with ration of 25% to correct rolling. No switch is needed.





Computer APP


Software Installation


Connect the computer and the T8FB with an android USB data cable (No OTG cable needed)

Open the parameter setup software in the downloaded file,then power on T8FB



Choose Port Number (COM port will be automatic identified when connected), setting baud rate: 115200, 8-1-None (8 data bits, 1 stop bit, no parity check), click OPEN to connect.

Note When click OPEN to connect, the SETTING parts mentioned above will turn grey and can’t be changed and PARAMETERS at bottom right will be displayed






Software Interface Introduction



READ: T8FB data will be read and displayed on computer when click “READ “and two D sounds will be heard.

LOAD: The data file in TXT format saved will be loaded in the software.

UPDATE: Modify the data as wish then click “UPDATE” to change the parameter in T8FB. (two green LEDs on the right will flash once with one D sound).



SAVE The data read or set will be saved as TXT file in the computer. This is very helpful if there are several sets of radio data need to be saved or if one set of parameters need to be copied in different radios.




Parameters Setting Steps


① When parameters need to be modified, click READ first to input the original data into the software, then modify as wish and click UPDATE to output the modified data to T8FB.

② When parameters SAVE as TXT file need to be input, click LOAD first to input the saved data into the software then click UPDATE to copy them to T8FB.




Basic Menu


There are 6 parameters to setup: “REVERSE”” SUB-TRIM”” END POINT”” FAIL SAFE”” AUX-CH”” DELAY”



REVERSE: Defines the relationship between the transmitter controls and the receiver output for channels with option of NORM and REV. Refer to 3.4.2-REV (P11) for more details.


SUB-TRIM: Makes small changes or corrections to the neutral position of each servo. Refer to 3.4.2-SUB (P11) for more details.


END POINT: Sets the range of each channel (in percentage);

The most flexible version of travel adjustment is available. It independently adjusts each end of each individual servo’s travel, rather than one setting for the servo affecting both directions. Refer to 3.4.2-EPA-L &EPA-R (P12) for more details.


FAIL SAFE: Sets responsive action of model in case of signal loss or low Rx voltage (in percentage).

Refer to 3.4.2-F/S (P12) for more details.


AUX-CH: Defines the relationship between the transmitter controls and the receiver output for channels 5-8. Refer to 3.4.2 for more details.


DELAY: Adjust the ratio between the position of servos and the actual operation. Refer to 3.4.2-DELAY (P12) for more details.




Advanced Menu


There are six parameters setup ”D/R” “ATTITUDE” “ELEVON” “V-TAIL”PROG.MIX1/PROG.MIX2 as below shown, please refer to 3.4.2 (P12-14)  for more details.







① What is the order of the connections for APP--USB--T8FB?

The best order is: Turn on T8FB -- connect USB cable-- connect APP. When you connect the APP, the phone will prompt that open APP.


② Why the prompt box always be showed?

    Just make sure the key steps are right. There is some prompt box when you change from one function interface to other.


③ Why the voltage data is always move up or down when T8FB connect to APP, sometime is 0, sometime is 7.98v?

Just close the APP, then reconnect again will solve this problem.


④ Why the APP show the flashback reminder?

    Please contact our sales-after service, there’s maybe something wrong with the APP, we will send you an upgrade software to solve this problem.


⑤ What are the correct steps for the “READ”?

    In general, please click the “READ” first after connect T8FB to APP to make sure the data of APP is the default data or you setup last time.


⑥ How to restore factory settings?

    When the APP opened (don’t READ), the current data is factory setting data, you just need to push the “UPDATE” button, so restore the factory setting.


⑦ How to solve the problem if the APP always cannot connect to T8FB?

    Maybe there is something wrong with the android USB cable, if not, please contact our after-sales service.


⑧ The TXT document of “Smart-phone APP” and “the computer parameter setting software” can work for the same effect?

    In fact, both of the two files are the same, but you need change the name of computer software to “model01.txt”, then create a file box (model) at root directory in Phone, put the “model01.txt” in “model”.


⑨ How to find “SAVE” file (/model/model01.text)



⑩ How to solve the problem that the APP flashback when you click “LOAD” button.

You need to open the permissions.

Settings - Permissions - APPS - RadioLink T8FB- Accept.