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Receiver antena wire fix for Turnigy 9x8Cv2

#1
My receiver antenna wire broke on my Turnigy 9x8Cv2 receiver. It is broken right where the wire comes out of the black plastic case.

I am able to send signals to the receiver in very short distances.

Can I just solder the broken wire back together to fix it?
 

jhitesma

Some guy in the desert
Mentor
#2
Just soldering the wire won't work. I've salvaged a few of these RX's with broken antenna wires in three ways, but be warned you'll probably loose a good bit of range.

For either method you'll have to open the case and warm up your soldering iron then unsolder the stub of wire left attached to the board. I highly recommend MG desoldering wick - makes it super easy. The desoldering wick at radio shack is a joke, the plunger style solder sucker isn't horrible...but MG wick is hands down the best way to remove solder out of all methods I've tried. (Well, a professional desoldering iron with vacuum pump is great...but out of my price range!)

Method 1) Just take a piece of bare wire 31mm long and solder it where the center conductor of the original coax was. This works and I've had no range issues with park fliers in a small field with this fix.

Method 2) If the original coax on the antenna is still in good shape you can strip back the insulation carefully, twist the shield off to one side, strip off a bit of the inner insulation and then solder the braid and conductor back like the original stub was. This is really tricky to do right though. It's very easy to miss a loose strand of wire from the braid and end up with a short. You also want as little of the conductor exposed as possible since it will try to act like an antenna and detune things. The first one I tried doing this to seemed to work...but range was VERY limited - like 100 yards. The second one I did this to I was more careful and seem to have almost full range still.

Method 3) Take an antenna from a different broken 2.4Ghz RX and swap it over. I did this with the antenna from a 3ch RX that failed after a couple of crashes (these will bind with a 9x TX and work well on park fliers...but there's a component on them that's only supported by two tiny wires and after a couple of hard crashes those wires can break so they aren't great air RX's) The one I did this to works and has better range than the one with just a piece of wire and the first one I tried repairing the antenna on.

You could also try taking something like this http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=16666&aff=687394 and cutting off the connector then soldering it on.

Or you could try making a dipole, or turnstyle, or other antenna - a google search will give quite a bit of info on antenna design and it's not all that difficult.
 

Tritium

Amateur Extra Class K5TWM
#3
And for future thought, a shot of hot glue at the point where the antenna wire exits the case can slow and or prevent future broken antenna wires.

Thurmond
 
#4
Thanks, i think i'm just going to buy a new transmitter module xD

the stupid thing should be using a connector like U. FL

It's impossible to solder without exposing the two wires, i tried covering with paper o_O maybe glue gun will fill the void enough for them to not interfere with each other?

I'm going to try and reposition the receiver as well, im not sure how much of an affect this will have


Just soldering the wire won't work. I've salvaged a few of these RX's with broken antenna wires in three ways, but be warned you'll probably loose a good bit of range.

For either method you'll have to open the case and warm up your soldering iron then unsolder the stub of wire left attached to the board. I highly recommend MG desoldering wick - makes it super easy. The desoldering wick at radio shack is a joke, the plunger style solder sucker isn't horrible...but MG wick is hands down the best way to remove solder out of all methods I've tried. (Well, a professional desoldering iron with vacuum pump is great...but out of my price range!)

Method 1) Just take a piece of bare wire 31mm long and solder it where the center conductor of the original coax was. This works and I've had no range issues with park fliers in a small field with this fix.

Method 2) If the original coax on the antenna is still in good shape you can strip back the insulation carefully, twist the shield off to one side, strip off a bit of the inner insulation and then solder the braid and conductor back like the original stub was. This is really tricky to do right though. It's very easy to miss a loose strand of wire from the braid and end up with a short. You also want as little of the conductor exposed as possible since it will try to act like an antenna and detune things. The first one I tried doing this to seemed to work...but range was VERY limited - like 100 yards. The second one I did this to I was more careful and seem to have almost full range still.

Method 3) Take an antenna from a different broken 2.4Ghz RX and swap it over. I did this with the antenna from a 3ch RX that failed after a couple of crashes (these will bind with a 9x TX and work well on park fliers...but there's a component on them that's only supported by two tiny wires and after a couple of hard crashes those wires can break so they aren't great air RX's) The one I did this to works and has better range than the one with just a piece of wire and the first one I tried repairing the antenna on.

You could also try taking something like this http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=16666&aff=687394 and cutting off the connector then soldering it on.

Or you could try making a dipole, or turnstyle, or other antenna - a google search will give quite a bit of info on antenna design and it's not all that difficult.
 

RichB

Senior Member
#5
You can do it!

The tiny wire (like most all antenna feed lines) is actually coaxial.

Kind of like this: RG-59.jpg but much, much, smaller.

The trick with coax is the outer conductor (B) and inner conductor (D) must not touch!

The trick with antennas is the inner conductor must not be uncovered, it must be enclosed inside the sheath, right up to the point where it is uncovered (inside the red heat shrink on your receiver) intentionally for a certain distance to make the antenna.

So, just soldering the "wire" back together won't work.

The good thing is though, that with a fine-tip iron, this repair isn't that hard. You will need to take the case off the receiver. Then find where the remaining stub of antenna feed line is, and remove it from the board by melting its solder as you gently pull.

The delicate part is to simply strip a small length of insulation (A) off the fresh end, and twist the sheath (B) into two pigtails 180-degrees apart. Much like the above image, except use half of the outer conductor on each side to make two instead of one. Then strip a little bit of the inner insulation (C) off the core (D), and solder all three contacts down like you found the stub.

I realize that this sounds complicated, but if you just take the time to remove the two screws and open that receiver box, it will make sense.

Anyway, you will wind up with a slightly shorter feed line, but it will be back to full function.

Definitely do the hot glue trick when you are done to add some strain relief.
 

joshuabardwell

Senior Member
Mentor
#7
The tiny coaxial cable used in some of the receiver pigtails often doesn't have a braided sheath, but has foil instead. In this case, simply strip it back and bridge a dab of solder between it and the appropriate pad. You can also do this with the braid, but twisting the braid a bit helps make sure there are no stray wires to accidentally touch something undesirable.