Fixed – Inverter Mod for TBS Crossfire and FrSKY QX7 & X10S


The current hardware revision of FrSKY QX7 is not fully compatible with the TBS Crossfire protocol.
If you get constant telemetry warnings you might be affected. The reason is a wrong inverter on the FrSky QX7 wich can not handle the 400k baudrate of the CRSF protocol.
Your Radio Link to the aircraft is not affected, just the telemetry or LUA Script. 

Solution 1: Software fix

You can set the Baudrate to 115200 and your Crossfire Module will work without any issues.
Be aware: The lower baudrate will slow down the CRSF protocol

This workaround will give you a baudrate selection on your X7 menu (main menu, hardare page). If you lower it to 115’200baud instead of using 400’000baud the issue is resolved. Due this workaround and the lower baudrate the latency will increase. The regular update rate for CRSF between OpenTX and Crossfire is 250Hz (4ms). Using the lower baudrate the update rate is reduced to 62.5Hz (16ms). Because of this we recommend to fix it properly in hardware if you have the soldering skills or ask FrSky for support on fixing the hardware.

  1. Download latest Taranis Firmware
  2. copy the firmware onto the SD Card into the „FIRMWARE“ folder
  3. start the Taranis in bootloader mode
  4.  flash firmware and select 115200
  5. Go Fly!


Solution 2: Hardware fix

I created the following PCB wich TBS and many online shops now sell. With this mod, you can get the full 400k baudrate for your TBS Crossfire System.
You can get this Inverter via TBS or for example the german FPV Racing Online Store

Warning: Only do the hardware mod if you know what you are doing. To desolder SMD components you need a bit of tact. The components around it can be damaged very easily if you don’t do it correctly. Please make these modifications only on your own responsibility/risk. Neither TBS, FrSky or I can guarantee that the mod works! Thank you!


Please follow the guide below:

Have fun!

Mod for FrSKY Horus X10S

Thanks Yann Bouloiseau for the photos and information for this mod!


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14 Antworten

  1. Mitch sagt:

    Hi Philipp, thanks for your work. Do you have part schematics so I can make my own mod? I cant find local retailer of your mod.


  2. clifyb sagt:

    Hi Phil, I didn’t realize I had the older QX7 and went ahead and did the mod you listed above and i doesn’t work. I later read the „S“ pin on the lower sPort is not functional on the older QX7 radios so I seem to have disabled sPort on the rear bay port pins too. Can I recover this by wiring the „In“ wire to one of the pads at the Q400 location? Thanks

    • clifyb sagt:

      Update: I recovered from my unneeded Q400 mod on my early QX7 by moving the ‚In‘ wire from the non-functional „S“ pin on the sPort per your official mod; and moving it to the Q400 transistor pad farthest from the „Q400“ label. Now it flashes my Rx’s just fine from the rear bay port pins like the X9 and I’m using the latest part from your cool mod PCB too, so Crossfire works fine too.

  3. Yi Joe sagt:

    hi umm i am new and can i ask you a question? will i hard the q x7 if i remove the part q400 with a hot air gun? will it be too hot?

    • Phil sagt:

      Hi Yi Joe,

      if you are not familiar with hot air desoldering please be carful. Grab an old pcb and practice a little.

      The other way, would be with a tiny soldering tip. First lift the one leg and then heat up both legs together on the other side to remove the component.

      But be careful with all the smd components around the Q400. There is at least one person i know who messed up the board, because the accidentally damaged some other parts on the PCB.


  4. GBaquero sagt:

    The X7S has that problem too?

  5. Jure Peternel sagt:

    Hi, am I missing something: why would I need this mod for use with TBS MicroTX? I have this setup and I’m flying without a problem :/

    How are the errors demonstrated? How can I check if I have a problem? Thanks

    • Phil sagt:

      Hi Jure,

      not all Radios are affected. Some older batches seems to work without the hardware mod (like my Q X7). But the most Q X7 and X10/S have this failure.

      Errors will be constant telemetry warning and crashing LUA Scripts.

      If it works on your Radio, your are very lucky and don’t have to change anything. But be shure you run it on 400k Baudrate. 😉


  6. the_mazur sagt:

    After „Hardware fix“ in menu need back Max bauds to 400000?

  1. 26. November 2017

    […] Vorheriger Beitrag Fixed – Inverter Mod for TBS Crossfire and FrSKY QX7 […]

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