Frsky kindly sent me their latest Tandem X20 radio for review. At the time of publishing, Frsky is still working on perfecting the operating system. In this post I will share the main features and what you can expect from the new Tandem X20.
What I have here is a pre-production unit, so things could change in the final version, especially the software. If there’s any new features or improvement, I will let you know right away by updating this post.
Where to Buy?
Before purchasing, make sure you choose carefully between FCC (US) and LBT (EU), because the internal antennas are tailored for the different frequencies used in these regions.
There will be 3 versions, Standard, S, and HD. What I am reviewing here is the Standard version.
The following table explains what features the S and HD versions will have on top of the standard version. Note that the HD will have “built-in 0ms latency HD digital Video Transmission System (720p 60FPS)”, which is super interesting! It’s Frsky’s own HD system and won’t be compatible with DJI’s, I can’t wait to see how they compare :)
It will be using the screen to display live FPV video, and it can output video to your FPV goggles through HDMI which is really neat.
Frsky Tandem X20 Key Features
- Beautiful build quality – totally live up to its $300 price point IMO
- NO OpenTX! It’s using a new system called EthOS, developed by Frsky
- Dual Bands: 2.4GHz and 900MHz are built into the radio
- Supports external RF module with its Lite module bay (NOT JR), it will support Crossfire in the future
- Frsky claims the maximum range is up to 50Km to 100KM with ultra low end-to-end latency down to 3ms
- 800*480 Color Touch Screen
- It has built-in gyro, you can control an RC vehicle by simply moving the radio
- Hall-Sensor Gimbals with CNC Metal Panel
- Weight: 934g including battery
Frsky is replacing OpenTX on their new radios with a new operating system, EthOS. You can learn a bit more about EthOS here: https://ethos.frsky-rc.com/
This is how the Model Setup Page looks like:
After using EthOS for a while now, I find it easier to use than OpenTX, everything has little nice icon, and it’s very easy to navigate and understand even though it’s my first time. OpenTX is a bit more like Linux while EthOS is more like Windows, where EthOS is more graphical.
Mixer tab looks like this:
The user interface of EthOS is super clean, and both OpenTX and EthOS share many of the same features, and so the transition was actually quite easy.
However EthOS is still in its early stage when it comes to development. It’s working as it is right now, but certainly there are still many important options missing. The developers are busy working on EthOS, and there is almost a monthly firmware update – my radio was shipped with 0.0.12 (January), by Feb it was 0.0.15 and now it’s already on 0.0.17.
According to Frsky, EthOS will also support LUA script so hopefully with the help of the community and Frsky, we could use the same LUA scripts for changing Betaflight settings (although it’s no longer a big deal as you can do that in Betaflight OSD anyway).
Currently (Apr 2021) I still can’t play FPV simulator through USB with the X20, a known issue related to EthOS. Right now I could use the XSR-SIM, or Betaflight to play sims. Hopefully this is something Frsky can address before launching the X20.
Tandem X20 Protocol Supports
The Tandem X20 is pretty much intended to be used with Frsky’s latest Archer and Tandem receiver families.
But it will also support older receivers that runs ACCESS protocol, as well as the ACCST 2.0 D16. Note that it’s ACCST V2! It does not support the older ACCST V1 (both D8 and D16). If you must use ACCST V1, you can get an XJT Lite module and plug it to the back of the radio (which also supports L9).
The upcoming Tandem receivers will be using both 2.4GHz and 900MHz frequencies simultaneously, making them a lot more versatile. And the claimed maximum range of this system would be up to 50km to 100Km with ultra low latency, sounds very impressive indeed.
Does it support TBS Crossfire, now?
No, but Frsky is working on it as we speak. Right now, the X20 supports the following external modules:
- XJT Lite
- R9M Lite
- R9M Lite Access
- R9M Lite Pro Accesss
Frsky is aware of this issue and hopefully it will be addressed by the time the X20 is released. Personally I want the X20 to support Crossfire so badly as I am so invested in it (9 out of 10 of my quads are Crossfire), if I had to replace all the receivers, that would get really expensive.
Closer Look at Tandem X20 Hardware
The Frsky Tandem X20 looks really professional and the build quality is just brilliant.
The screen is a 800×480 color touch screen – it’s intuitive to use and responsive, certainly a great addition to menu navigation. It’s so nice to have when you want to get to a particular option instantly without clicking through a million other options.
The display is bright and the viewing angle is excellent.
There are 8 switches on the X20, the configuration is exactly the same as the other Frsky’s radios such as the Taranis X9D and Horus X10.
There are 6 “Quick-Mode Custom Buttons” next to the menu buttons. The red slider in the centre is just an additional slider on top of the two standard sliders on the sides.
The X20 has internal antennas for both 2.4GHz and 900MHz (hidden inside the radio housing), and there are also RP-SMA connectors if you want to attach external antennas for better range. You can choose which antenna to use in the RF settings.
Between the RP-SMA connectors, there are more connectors under the rubber cover, from right to left: Trainer port, S.Port (SmartPort) for flashing receivers/RF modules, USB-C port for charging and data, micro SD card slot and 3.5mm headphone jack. There are a couple of empty spots in the middle, those are reserved for the more expensive models, such as mini HDMI port for video output.
Note that the Tandem I received didn’t come with an SD card. See my recommendation on which SD card to get for your radio.
There are two momentary buttons on the back of the radio (next to the module bay).
On the back, there’s an external “Lite” module bay (not JR). The radio comes with a 2S 4000mAh LiPo, which can be charged through the USB-C port.
Comparing to the TX16S
The Tandem X20 has all the expected features of a high end OpenTX radio, such as voice read out and haptic feedback (vibration). You can also use the sound pack designed for OpenTX such as the Amber sound pack in the X20, as well as model images designed for OpenTX radios like the TX16S. The Telemetry screen is just as customizable as OpenTX.
Comparing the Radiomaster TX16S to the X20 side by side, the X20 is slightly larger. They both weigh around 935g including battery, but the X20 feels like a more solid radio in hands thanks to the matte, rubbery finish.
Also the X20 feels more balanced when I am holding it, because the gimbals are located in the middle, while the TX16S feels a bit more bottom heavy as the gimbals are located on the top half of the radio.
Although the rubbery, matte finish of the radio looks and feels really professional and high quality, it’s also a “dust magnet” :) You’ve probably noticed how dusty the radio’s got after just a week of use in the pictures.
They even provided add-on grips that you can slide onto the sides, it adds some thickness to the radio if you have big hands and prefer chunkier grips.
I would feel more comfortable using the X20 as a thumber.
As a pincher, I feel like there’s lack of space on the top of the radio to rest my middle finger. I could still pinch with the X20, but sometimes I would accidently hit the switches on the top with my middle fingers, and it’s kind of awkward. Maybe it takes some getting used to.
You can adjust gimbal tension by removing the two rubber covers on the handles, without removing the whole back housing. But it is quite hard to see which screws you are turning. And to get rid of the ratchet on the throttle stick (which is default), you have to take the radio apart to do it.
This is all I have to share for now. You can check the price of the Tandem X20 here: https://oscarliang.com/product-ujtf
I will keep coming back to update this post as I learn more about this radio, meanwhile if you have any questions just let me know.
How to update Tandem X20 EthOS Firmware
- download firmware (.bin file)
- go into bootloader mode (hold both trim buttons inward then power on radio)
- Plug in the USB cable (must only do this after entering bootloader mode)
- Two external drives should appear on your computer (one 8MB, and the other your SD card)
- Copy the fimrware file to the SD card drive (the one with larger capacity)
- change the firmware file name to “firmware.bin”
- unplug USB
- your radio will detect the firmware file, and starts updating automatically, this should take 30 seconds or so.