DIY 1000mW 2.4gHz RF Amplifier

BOM and gerber files now avalible:

https://github.com/s52mp/OpenRcAmp

SKY65162

I designed a low cost 2.4ghz RF Amplifier based around SKY65162-70LF. The SKY65162 offers wide frequency operation range and is suited for both 900mHz and 2.4gHz both very popular in the RC comunity.

The RF amplifier IC is a 400 to 3800 MHz Linear Power Amplifier that can output up to 30.0 dBm with 20.0 dBm gain.

My Diy amplifier mounted on the turnigy 9x transmitter

Schematics

Passive components for 2.4gHz

I created the chematics based on amplifiers typical aplication which also offers component values for its operation bands and than designed a 4 layer pcb following the manufacturers sample design found in the data sheet.

PCB layout

I calculated the prefered 50Ω impedace between first and second layer with the Saturn PCB toolkit using the PCB manufacturers PCB stackup. For 2.4ghz I calculated the track width to be 13,5 mils.

For PCB manufaturing I arranged my designes in an array to maximize the PCB quantity that I could acquire for the same price.

Amplifier all up cost

My diy amplifier sould cost less than the solutions you can find on the market.

costs per 1 PCB:

PCB =~ 0,5€

SKY65162-70LF =~ 2,93 €

Passive components =~ 1€

RF connectors =~ 3€

Aluminium housing = Time spend on your CNC router

All up cost =~ 7,5€

Projects progress

I have already soldered the passive 0402 components which is shown in this video which I recordered it with my DIY smd microscope adapter.

I have also finished the amplifier housing. It is made out of alumimium and offer great rf shielding and heat decipation.

When the project is completed I will test its output power and RC link range increase.

Diy 5,8 GHz FPV patch antenna

I made a FPV 5.8GHz biquad antenna from scratch. This makes it a linear polarized antenna mustly suited for flying tiny whoops and other drones with a linear polarised antenna.

The tutorial includes the detailed construction of the antenna. Antenna has a 9-10 dBi upfront gain and 70% of the total gain at 60 degress, which makes it comparable to the middle priced patch antennas on market.

5,8 GHz FPV patch antenna

Parts required:

  • Coax cable with connector of your choice (I am using male SMA)
  • 50 x 40 mm blank PCB
  • 0.5-1 mm thick copper wire
  • Option: 3D printed cover

Making the reflector

From a black PCB cut out a 50 x 40 mm ractangle. (You can use any thin bladed saw but be careful of glass fibre dust that is not the best thing for your lungs.) To complete the refloctor mark and drill a 3mm hole in the middle.

The reflector should look like this.

Making the element

To make the element cut the 0.5 – 1mm thick copper wire at 104mm.

On the wire mark 8 13mm long sections and using pliers bend the wire in the correct shape. Using thinner wire will result in the easier bending but will be less structual rigit.

The end element should look like this:

Prepering the coax cable

Upon acquiring the coax cable stip obout 1 cm of outer insulation.

Once you have stripped down the insulation peel back the shielding to expose the inner insulation.

At last remove the inner insulation to expose the center conductor.

Assembling the antenna

Firstly route the coax cable through the previously made reflector. Make sure that the distance betwen the end of the insulation and reflector is 6mm.

Once the cable is inserted make sure it is facing straight out. Proceed with the soldering of the shielding to the reflector.

Proceed with the most tricky part of the assembly: Soldering the element to the coax. Solder one end to the center conductor and one to the shielding. Make sure they are not touching.

For the end you can 3d print a cover for your newly build antenna. STL file is awalible here: https://www.thingiverse.com/thing:4550555?fbclid=IwAR16yUGmdZZo_ozAh10Msc5Y5HOJ-F7W2w1ktqxOS49i9ML7czGfBLFo7pI