How to Setup Jumper T20S Radio | Upgrades, Tips and Tricks

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I will show you how to setup Jumper T20 / T20S radio transmitter for the first time, and get the most out of it. I’ll guide you step-by-step through setting up the EdgeTX radio and also show you some tips and tricks, and potential hardware upgrades to elevate your user experience.

Still wondering if the T20S is the ideal radio for you? Check out my in-depth review of the Jumper T20/T20S here: https://oscarliang.com/jumper-t20-radio/

Installing Antenna

Ensure that the included antenna is attached before powering on the radio. Powering on the radio without the antenna can cause the RF chip to overheat quickly or even become damaged.

Remember, NEVER turn on the radio without antenna!

Battery Installation

The battery compartment is located on the back. To power up your Jumper T20S, you’ll need either two 18650 or 21700 Li-ion cells. Batteries are not included, but you can purchase them here:

21700 Li-ion cells:

• RDQ: https://oscarliang.com/product-njo4
• GetFPV: https://oscarliang.com/product-nnl6
• Amazon: https://amzn.to/3YJl15c
• AliExpress: https://s.click.aliexpress.com/e/_DCxHS4X

18650 Li-ion cells:

• Radiomaster: https://oscarliang.com/product-0239
• Amazon: https://amzn.to/2W93Uwp
• GetFPV: https://oscarliang.com/product-h1sg
• RDQ: https://oscarliang.com/product-1np7

With 21700, it’s a pretty tight fit and it takes a firm push to close the battery bay lid. 21700 cells have considerably larger capacity than 18650, so you should get longer battery life, however they are also heavier which can affect how the radio feels in your hands.

This battery holder is compatible with 18650 cells too, just pull the contacts outwards so they can hold the smaller 18650 batteries securely. I personally prefer 18650 for its lightweight and weight balance, even though run time is shorter.

Potential Start-up Warnings

To power on, press and hold the radio’s power button for a couple of seconds. You will be greeted by the EdgeTX splash screen.

Ideally, a brand new radio should turn on without any issues. However, if you are prompted by a warning, don’t panic. Here’s a breakdown of potential warnings and their quick fixes:

• Throttle Warning: This pops up if your throttle stick (the left one for Mode 2 radios) isn’t at its lowest position when powered on. Pushing it all the way down will get rid of this warning.
• Switch Warning (also known as Control Warning): This signals that some switches aren’t in their default positions. To clear this, ensure all switches are in their HIGH position
• Alarms Warning: This appears if the Sound mode is set to mute. If you configure this on purpose, you can press the Enter button (scroll wheel) to safely skip this warning, otherwise enable Sound again in Radio settings.
• SD Card Warning: This indicates a version mismatch between the SD card content and firmware. If you get this warning, follow this guide to fix it

If everything goes well, you should land on the radio’s default home page.

Radio Settings

The Radio Settings are where you’ll adjust your display, audio, system related parameters, and so forth.

Kick things off by holding down the menu button for a couple of seconds (the first button on the left of the control panel), this will take you to the TOOLS page. From there, short press the PAGE button twice (the second button on the left of the control panel) to scroll to the Radio Setup page.

I’ll walk you through the initial changes you might want to consider. Anything I skip over can be left default.

1. Set Date & Time.

2. Battery Range:

• For Li-ion battery: 6.4V – 8.2V
• For Lipo battery: 7.4V – 8.2V

Why these ranges? This setting defines the battery indicator on-screen, specifically when it displays as full or empty. You might wonder about the minimum 6.4V for a 2S Li-ion, which can indeed be discharged even more. Yes, you can set it to 6.0V. However, having it a tad higher offers an earlier visual cue. As for the 8.2V max (instead of 8.4V), it’s due to voltage sag. The moment you power up, the battery’s voltage drops slightly. You will never see 8.4V on screen, so think of 8.2V as “fully charged.”

3. Sound:

• Mode: Opt for “All” to hear “beeps” when navigating the menu. Alternatively, go with “Nokey” if you prefer more silent operation.

4. Alarms:

• • Battery low (threshold for audio and haptic warning, if you fly long range you might want to set this higher so you have enough battery to make your way home.)
    • For Li-ion: 6.4V
    • For Lipo: 7.4V
  • Inactivity: 10 minutes (if the radio is left untouched for this duration, you will hear the “inactivity alarm” audio reminder)

5. Pwr On delay: 1s

This is the time it takes to hold down the power button to turn on the radio.

6. Pwr Off delay: 1s

This is the time it takes to hold down the power button to switch off the radio, this is a safety feature to avoid accidentally turning off the radio. I personally set it to 1s for faster shut down, but if you want to play safe you can set it longer.

7. USB mode: “Ask”.

8. Lastly, press the PAGE button a few times to go to the Hardware page, ensure the ADC Filter option is turned off (unticked). Why? See this section.

Adjusting Stick Travel

One unique feature of the T20 is the ability to increase or decrease gimbal stick travel.

To adjust horizontal gimbal stick travel, simply remove the two screws circled in the following image, and push the metal bracket which limits how much you are allowed to have.

To adjust the vertical stick travel, remove the metal covers on the top and bottom of the gimbal, which reveals the screws that limit how far the stick can travel.

You should always calibrate your gimbals again after adjusting stick travel.

Adjusting Stick Length

Adjusting stick length is a breeze by rotating the screw inside the stick end using a 1mm hex screwdriver.

Adjusting Gimbal Tension

To customize your control experience, the T20 allows you to adjust gimbal spring tension, but it requires tearing down the radio first. There are 10 screws to remove, and you also need to loosen the two top switches.

Carefully disconnect the ribbon cables before fully lifting the back housing.

Here’s a diagram showing where the gimbal tension screws are for roll, pitch, yaw and throttle.

Gimbal Calibration

Before flying with a new radio, you should always calibrate the gimbals.

Navigate to the Radio Setup page, then hit the PAGE button a few times till you land on the “HARDWARE” page. From there, select the “Calibration” option. This will initiate the calibration process for both the sticks and sliders. The on-screen instructions are clear, so just follow along.

Make sure you only move the sticks as shown in the following image. For best result, avoid moving the sticks in circle. Be as gentle as possible when pushing the sticks, so the radio reads the end points correctly.

Make sure you also move the sliders and rotary switches, set them to their middle position before calibration. You also need to calibrate the 6 flight mode buttons, they are actually treated as a slider in the radio. If your flight mode buttons are not working, chances are you haven’t calibrated them correctly yet.

Battery Voltage Calibration

To ensure you’re getting the most precise battery reading possible, take a moment to calibrate your radio’s battery voltage.

With a digital multimeter in hand, measure the voltage of the batteries inside your radio (while the radio is powered on). Given that the cells are connected in series, you should expect a reading between 6V to 8.4V. The goal is to make sure the measurement on your multimeter matches the one displayed on your radio.

Navigate to the “HARDWARE” page, scroll down until you find the “Batt. calib” (Battery Calibration) option. Using the scroll wheel, get the voltage as close to your earlier measurement as possible.

Flight Mode Buttons Labelling

The T20 comes with stickers for the flight mode buttons. If you fly iNav or ArduPilot, it’s a good idea to label all the buttons to help you remember what they do. This is optional.

Here’s mine.

Switch Covers and Custom Switch Nuts

Silicone Switch Covers:

• AliExpress: https://s.click.aliexpress.com/e/_DEeR767
• BG: https://oscarliang.com/product-7vcb
• RM: https://oscarliang.com/product-6tjc

Custom Switch Nuts:

• AliExpress: https://s.click.aliexpress.com/e/_DeSVnF9
• GetFPV: https://oscarliang.com/product-esfp

Stick End Upgrades

I felt the T20’s stock stick ends lack grip, so I upgraded mine to the Sticky360, you can get the M3 version for the T20 gimbals here:

• Radiomaster: https://oscarliang.com/product-xo4g
• GetFPV: https://oscarliang.com/product-kk4b
• RDQ: https://oscarliang.com/product-ih0l
• AliExpress: https://s.click.aliexpress.com/e/_DegTW2Z

Swapping Switches

I swapped the 2-position and 3-position switches, because I normally use the 2-position switches to arm and disarm, having them closer to the gimbal makes them easier to reach while flying.

Neck Strap Balancer

Due to the location of the battery bay, the T20S is bottom heavy and it won’t balance on the neck strap out of the box. An easy solution is to use a neck strap balancer.

I bought this one a few years back for the Taranis X9D, and it works perfectly on the T20 as well. Get it here:

• AliExpress: https://s.click.aliexpress.com/e/_DBBbrqb
• Amazon: https://amzn.to/2URPg8s

Model Profile

The T20 comes with a model profile pre-created for you, it’s just called “Model01”. To see the model selection, short press the menu button (top button on the left of the control panel).

While this model has some basic configurations, you need to assign switches in MIXES before you can fly.

To go to MIXES, short press the menu button, then press the PAGE button a few times until you are in MIXES. Go down to CH5, select Edit, and assign whichever switch you want to use for arming. Repeat for CH6, CH7 and CH8 if you wish to use more switches for other things like flight modes, turtle mode and beeper.

If you need help on how to assign switches, here’s my tutorial: https://oscarliang.com/betaflight-modes/#How-to-Setup-Arm-Switch

Here’s the end result of my radio MIXES setup:

More tutorials on ExpressLRS:

• For ExpressLRS receiver binding, follow this guider: https://oscarliang.com/bind-expresslrs-receivers/.
• If you’re using the multiprotocol CC2500 version, find setup details here: https://oscarliang.com/setup-tx16s-t16-radio/#model-settings

Creating a Profile for FPV Sims

Planning on practising in an FPV simulator? Consider creating a dedicated model profile for this purpose.

To do this, start with making a duplicate of your existing model profile for your drone. Then change its name to something else such as “FPV Sim” or just “Sim”.

In Model Setup, scroll down and switch both “Internal RF” and “External RF” to OFF. This will save battery life when you are playing FPV sim and prevents the internal RF modules from getting hot.

Backup and Restore Radio

I recommend backing up your radio settings regularly (e.g. before firmware updates and whenever you make big changes). Fortunately, with EdgeTX, backing up and restoring your radio’s settings is simple and hassle-free.

Normally, EdgeTX radios use a micro SD card to store everything (aka SD card content), but the T20 has a onboard memory chip for this.

Follow instructions here to backup and restore your radio SD Card Content: https://oscarliang.com/backup-restore-models-radio-settings-edgetx/

Easy Volume Control

Your Jumper T20S is equipped with two rotary controls in the control panel (S1 and S2). They might not be useful for people flying multi-rotors, and we can turn them into a volume control. The trick is to create a function in the radio. You can either do this in “Special Functions” in the Model Setup, or “Global Functions” in the Radio Setup. I prefer to do this in Global functions because it applies to all model profiles, saving you the need to set them up individually for each profile.

1. Navigating to Global Function: Hold down the Menu button, then a few taps of the “PAGE” button will take you to the “Global function” page.
2. Creating Function: Find a empty slot and select “ON”.
3. Setting Up Volume Control: In the 2nd parameter, select Volume, in the 3rd parameter, select the rotary control by moving it with your fingers, and finally enable it by ticking the box.

Updating EdgeTX

Backup your SD card first before updating EdgeTX.

1. Checking Firmware Version: Navigate to the system menu by heading to Radio settings => Versions. This step helps identify the version currently running on your radio and whether you need to update.

2. Using EdgeTX Buddy: This online tool is the most user-friendly method for updating the EdgeTX firmware. For a detailed step-by-step guide on using it, refer to: https://oscarliang.com/flash-edgetx/.

Updating Internal ExpressLRS Module

If you have the ExpressLRS (ELRS) version, updating the internal module is easy. The procedure is identical to the Zorro: https://oscarliang.com/update-zorro-elrs-firmware/. Here’s a summary of the steps:

1. Connect the T20 to your computer using the top USB-C port. Opt for the “USB Serials (VCP)” mode.
2. Download, install and run ExpressLRS Configurator program, choose “Jumper 2.4GHz” as the device category and select “Jumper AION T-20 2.4GHz TX” as the device.
3. Build Options:
   1. Go with EdgeTXPassthrough as your flashing method.
   2. Set your regulatory domain. For instance, use ISM_2400 for FCC users.
   3. Enter your unique binding phrase
4. If flashing via USB, click “Build & Flash”.

Tips and Tricks

Custom Sound Pack

Bored of the default voice prompts? Try custom sound packs. Amber Sound Pack, for instance, stands out with its superior sound quality.

Download: http://open-txu.org/home/version-2/v2-2-resources-2/

After downloading, extract the files and replace the originals in the SOUND/en folder on your SD card.

Playing Custom Sounds

Did you know you can play custom sound files, even your favorite tunes, on any EdgeTX radios? If you’re new to this, here’s a tutorial to create custom sound files for OpenTX radios, the same steps apply for EdgeTX: https://oscarliang.com/taranis-play-sound-track-mp3-files/

Filename limits: Ensure the filename is no more than 6 characters, with the file extension capped at 3 characters. Also, dodge any special symbols in the name. The ideal file format: 32000kHz Mono Wav.

Exploring the Tools Page

The Tools page on your EdgeTX radio is a collection of useful LUA scripts. One frequently used LUA script is ExpressLRS, which allows you to configure your ExpressLRS module.

Button Cell Battery Replacement

If your radio is constantly forgetting the date and time settings, it’s likely the button cell battery is dying. Look for a Lithium 3V CR1220 battery. Conveniently, you can get them online, for instance on Amazon (affiliate link): https://amzn.to/3yDyDBe

Upgrading to AG01 Gimbals

You can upgrade to the AG01 gimbals, here’s my step by step tutorial: https://oscarliang.com/install-ag01-t20s/

Switch Rockers and Knobs Upgrade

Purely aesthetic upgrades, but do look nice.

• AliExpress: https://s.click.aliexpress.com/e/_DlJZXBJ
• Banggood: https://oscarliang.com/product-7pbv

V2 Shell Upgrade

Here’s the V2 housing upgrade.

It features a slightly different design, particularly around the gimbals, with no more “recess.” It also includes a translucent plastic ring that adds a bit more depth, which is great for the LED ring mod. The housing is available in transparent and grey color options. I love the transparent version because you can see the LED lights through the housing.

Get the V2 Shell here:

• AliExpress: https://s.click.aliexpress.com/e/_DnpJk8z
• Banggood: https://oscarliang.com/product-r8sa

The same AG01 gimbal upgrade also works with this housing, but it requires an additional 2mm spacer: https://makerworld.com/en/models/520373#profileId-436766

I also added a couple of feet to the T20S so it can stand upright on the table: https://makerworld.com/en/models/156330#profileId-171256

Additionally, I installed a flexible handle on the back: https://www.thingiverse.com/thing:6229830

Finally, I added folding antenna supports. They’re kind of unnecessary but why not: https://www.thingiverse.com/thing:6286666/files

I printed all these parts in TPU, and they work great.

Not sure if you noticed, but I also moved the switches around, using only the top holes. The hole closest to the gimbal is a bit too close to the hand when pinching, and I sometimes hit the switch by mistake. So, I decided to move that switch further away. It took about a week to get used to this new switch location but it’s worth it.

Conclusion

We hope this guide has been helpful in setting up your Jumper T20/T20S radio. I will be updating this guide if there are other useful mods and upgrades.