# Cant arm with rc **URL:** \ **Category:** PX4 Autopilot\ **Created:** [October 20, 2016, 6:08am UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517 "2016-10-20T06:08:55Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![seth](https://discuss.px4.io/user_avatar/discuss.px4.io/seth/32/465_2.png) [@seth](https://discuss.px4.io/u/seth)\ **Post date:** [October 20, 2016, 6:08am UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/1 "2016-10-20T06:08:55Z")
new to px4 and pixracer. new build of 130mm quad. pixracer running standard px4 firmware. all the checks disabled - like a racer. arms fine in qgc. will not arm via rc. I feel sure i am missing something dumb - but after hours of looking I have no idea what. All thoughts appreciated, seth ---
**Author:** ![andrejpan](https://discuss.px4.io/user_avatar/discuss.px4.io/andrejpan/32/3611_2.png) [@andrejpan](https://discuss.px4.io/u/andrejpan)\ **Post date:** [October 20, 2016, 7:45am UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/2 "2016-10-20T07:45:13Z")
I guessing that you calibrated the RC? Also there is a RC parameter which selects what kind of input you have (joystick, RC and one more thing, that I do not remember right now) ---
**Author:** ![seth](https://discuss.px4.io/user_avatar/discuss.px4.io/seth/32/465_2.png) [@seth](https://discuss.px4.io/u/seth)\ **Post date:** [October 20, 2016, 2:58pm UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/3 "2016-10-20T14:58:32Z")
Yes, and COM\_RC\_\_IN\_MODE is set to RC Transmitter. I’m using DX8i and Spektrum FPV Racing rx. Seems to bind fine with 11ms framing. I wonder if there is some problem between pixracer and this rx though. RC calibration is slow, and a little finicky. Not sure if its really picking up the whole range of stick movement, and seems a little deaf to the switch channels. I’ll search for more - perhaps there is some tx/rx setup that is wrong. ---
**Author:** ![DonLakeFlyer](https://discuss.px4.io/user_avatar/discuss.px4.io/donlakeflyer/32/3036_2.png) [@DonLakeFlyer](https://discuss.px4.io/u/DonLakeFlyer)\ **Post date:** [October 20, 2016, 7:25pm UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/4 "2016-10-20T19:25:46Z")
When you say RC Cal is slow are you connected over radio? If so, this can be the case. But over USB it should be fast and rock solid. If it isn’t then something is out of whack with hardware setup. ---
**Author:** ![seth](https://discuss.px4.io/user_avatar/discuss.px4.io/seth/32/465_2.png) [@seth](https://discuss.px4.io/u/seth)\ **Post date:** [October 20, 2016, 8:58pm UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/5 "2016-10-20T20:58:10Z")
This was USB, and since i began the rx has failed. Im guessing this is at least part of the problem. Waiting on stuff now 😉 ---
**Author:** ![seth](https://discuss.px4.io/user_avatar/discuss.px4.io/seth/32/465_2.png) [@seth](https://discuss.px4.io/u/seth)\ **Post date:** [October 20, 2016, 9:41pm UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/6 "2016-10-20T21:41:38Z")
fixed. bad rx. replaced spektrum fpv racing rx and dx8i with frksy x4r and taranis 9plus. worked first time. guessing bad rx - now i gotta decide if im gonna replace it or figure out how to sqz x4r on this 130! ---
**Author:** ![LorenzMeier](https://discuss.px4.io/user_avatar/discuss.px4.io/lorenzmeier/32/17_2.png) [@LorenzMeier](https://discuss.px4.io/u/LorenzMeier)\ **Post date:** [October 20, 2016, 9:53pm UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/7 "2016-10-20T21:53:42Z")
Its probably the new telemetry protocol on the DX8i. It will work with a DXe. We’re talking to Spektrum and a fix is on the way. ---
**Author:** ![seth](https://discuss.px4.io/user_avatar/discuss.px4.io/seth/32/465_2.png) [@seth](https://discuss.px4.io/u/seth)\ **Post date:** [October 20, 2016, 10:55pm UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/8 "2016-10-20T22:55:41Z")
would make sense for the beginning problems - it was configuring but oddly. but these later issues were due more to a failing rx - it would no longer rebind, for example. ---
**Author:** ![yun](https://discuss.px4.io/letter_avatar_proxy/v4/letter/y/bcef8e/32.png) [@yun](https://discuss.px4.io/u/yun)\ **Post date:** [November 11, 2016, 6:33am UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/9 "2016-11-11T06:33:23Z")
Hello, I met the same problem. I also cannt arm with the User’s Guide said “To arm the drone, put the throttle stick in the bottom right corner”. And now I have to arm by QGC but this is very trouble. Have you found the solution? Thank you ! My drone is VTOL TBS. ---
**Author:** ![seth](https://discuss.px4.io/user_avatar/discuss.px4.io/seth/32/465_2.png) [@seth](https://discuss.px4.io/u/seth)\ **Post date:** [November 11, 2016, 5:52pm UTC](https://discuss.px4.io/t/cant-arm-with-rc/1517/10 "2016-11-11T17:52:03Z")
I solved my problem when i changed to new rx and tx. uisng taranis 9d plus and frsky x4r. There also may be safety parameters that you have to change depending on how aircraft is configured. my 130mm quad does not have gps, for example, so i had to disable that in the the pixracer parameters using qgc. the various parameters are discussed elsewhere in this forum. hope this helps.