If like me, you are well impressed with the specification of the Spektrum DX3S, but very disappointed by its range, then this tutorial is for you. Since I got mine over 1 year ago I've been looking for ways to get it past the approximate 100 metre standard range without glitching. With this mod, I have gone as far as I can still see the car - and have even bent the transmitter aerial into a horizontal position to weak the signal (bad for 2.4g systems), and this had no effect.
The parts you will need are:
* RG178 coax cable
* Small screwdriver
* Soldering iron / solder
* Sharp knife
* Aerial tube
* Tape measure
* Drill and 2mm bit
Note that in this example, the photos were taken whilst modding my Rustler VXL receiver, but it is exactly the same principle for any other vehicle.
Get your stock receiver and clean it up
Using a small screwdriver, prise open the receiver case. It should come apart fairly easily. Separate the items and remove the electronics from inside
Using the 2mm drill, drill out the stock antenna hole in the top case.
Using a sharp knife, scrape away the glue from around the base of the stock aerial. Once the glue is cleaned away, heat the solder from the rear of the circuit board with the soldering iron to remove the stock aerial.
One you have removed the glue and aerial, you need the sharp knife again. Scrape away some of the screen board covering to reveal the gold circuit board underneath. Make sure you remove enough as you will later on need to solder the ground from the new antenna to this part.
Get your RG178 coax cable. Using the sharp knife, carefully strip the outer plastic covering from the cable. Do this about 1.5 - 2cm back from the end of the cable.
Once you have removed the outer plastic sheath, this reveal the braiding that goes around the inner core of the coax. Using a drawing pin or something sharp, carefully run this up through the braided cable starting near the top of the cable, working down towards the lowest part where you have exposed it. Take time here, as the fine strands are easy to break and they get easily knotted when you separate them. At the end, you want the braided part to be separated, exposing the inner core (which is also covered in plastic).
Once you have done this, twist the strands to form a fine single cable. Then, tin these strands using your soldering iron to form a solid core.
For the inner core, remove the plastic insulation a few mm above where the braiding is exposed - you do not want the two parts of the cable to touch each other or the aerial will be seriously compromised. Remove the plastic insulation to reveal the thin inner core. Twist these to form a fine core.
Going back to the circuit board, carefully tin the area of circuit board where you removed the green covering earlier.
Using the soldering iron, heat the just behind where the antenna comes throug the hole in the board to allow the solder to melt. At the same time, push the new antenna through from the component side of the circuit board. Once pushed through, solder the core fully into position.
Now solder the braided part of the antenna to the pre-tinned part of the circuit board you prepared earlier.
Trim the inner and outer cores so they are neat
Reassemble the receiver.