after a crash, my quad goes crazy, is it the Rx?

[Type-0]

I have a devention RX702 Rx that I use the devo7 Tx with.  the Rx has 2 antennas and I cut 1 short in a crash.
now I cannot fly my quad with the preset configure on remote that controls gps hold, return to home function or IOS . but if I switch the remote to a default and not the QR-x350 setting it flies great,  just has no switch settings.  the wire is 3.5 inches long and has a braded mesh wire wrap around it.  is it possible to solder a new 1 on and just cut the 10mm for the 2.4ghz?    or does the solder connection need to be shielded also?
if anyone knows what that 2nd wire is for and if this is what is causing my functions to not work and make my quad go crazy please reply.

[pk-surfing]

Your best bet will be to buy a replacement antenna such as this one....

http://www.giantshark.co.uk/product/169996/frsky-aerial-for-rx-15cm

(Out of stock at the Giant Shark shop)

I don't know your receiver but if you are lucky it will have the push on connector for the antenna so easy to remove the broken one and fit new.

The alternative is to do surgery on the cut coax, it would be fine if you could expose enough of the centre conductor and solder a thin wire to it.

Then measure the exposed length of the good antenna and cut the new one to exactly the same length (measure from where the outer braided shielding stops)

Hope this helps, and that it gets it working again

PK   :)

[MikeInUK]

do you have any way of viewing the output from the Rx ?

it's pretty straightforward to get an arduino to read & output channel data

[CurryKitten]

I have a devention RX702 Rx that I use the devo7 Tx with.  the Rx has 2 antennas and I cut 1 short in a crash.
now I cannot fly my quad with the preset configure on remote that controls gps hold, return to home function or IOS . but if I switch the remote to a default and not the QR-x350 setting it flies great,  just has no switch settings.  the wire is 3.5 inches long and has a braded mesh wire wrap around it.  is it possible to solder a new 1 on and just cut the 10mm for the 2.4ghz?    or does the solder connection need to be shielded also?
if anyone knows what that 2nd wire is for and if this is what is causing my functions to not work and make my quad go crazy please reply.

Aside from the antenna repair as other people have mentioned.  Obviously the radio and rx are working if you can switch it to "default" and fly around ok.  in this mode does it bypass the flight controller or something ?  Just wondered if it was work checking out your GPS, as the other modes sound like they need this to function, and perhaps some damage or loose wire happened in the crash ?

Can you actually tell it's in these modes from light flashes or anything ? Sorry if that's obvious,  I don't know this FC

[Type-0]

I did just order another Rx, but would like to salvage the broken one.  the antenna is soldered inside the Rx to 2 prongs that stick up off the board.
I would try to resolder a new antenna to the board if possible,  but I have 0 Tx/Rx experience. I have found the cut lenth, but I don't know if the connection to the board needs shielding to prevent interference.
I am sure the quad is in default mode when I switch,  the Rx and Tx have an automatic binding with any devo system. I have flown 3 different quads in the blank preset mode on my remote as long as they are walkera systems. so im %90 sure its default mode,  but I am a big noob.
I will receive a new rx tomorrow so this is mostly about learning things I should know and mabe having a spare rx to my remote so I can work on making a little plane.   I do appreciate everybodys replys and input, and hope others can learn also while reading this post.

[toys2]

Just answering the antenna part of your question, if I can see your picture correctly, I think that your RX could be saved
(sorry if you know this bit)
Each antenna is a coax cable, but it's only the last "bare" 31mm (for 2.4Ghz) that is the active part, the rest is effectively an extension, the extension is to get the antenna away from other electronics that could interfere or shadow the signal
Looking at your pic, you may be able to trim back the shield on the damaged RX to expose the 31mm of the core, the different lengths of the shielded part isn't an issue

Each coax is made up as follows, from outside in,
Outer PVC insulation > Mesh Shield or screen > Inner PVC insulation > wire core
So you simply need to strip off the outer pvc insulation and mesh shield, leaving the wire core and it's insulation to a length of 31mm

Here's a video that I found, but I DO NOT agree with his stripping method
- Mark the length as per the video
- using a fine scalpel, slowly slice through the outer insulation until it will slide off
- With a blunt round point (biro tip or similar) gently unweave the shield by working the pen tip to the end of the cable, you'll end up with a load of fine strands
- Now with clippers carefully nip off these strands, leaving the 31mm center exposed
- Don't overly flex the cable as per the video
How to repair a cut 2.4Ghz antenna -RC


In terms of the quad acting weird, I suspect something else is wrong, I would guess that one or more channels switch the FC modes or features? Are the signals for these channels getting through - RX > FC wiring ok etc?