Ribamodel Team

Portuguese Radio Control Airplanes, RPV/FPV/UAV


DIY 35Mhz 11 Watt Amplifier

When I started my researches on FPV, one of the main problems was the range on RC control, this was way before it started to appear the nowadays UHF RC Systems. I must admit currently I am using Dragon Link UHF 433Mhz system, which, with only 500Mw output, it gives a range of about 25Km. So I would not recommend this amplifier if you can afford a UHF system, otherwise, feel free to build yourself this amp.
    The amplifier is powered by 12volts, so you can use a 3S Lipo to power it. It uses the Mitsubishi 2SC1971 transistor, which, if you tune it perfectly, it can provide you about 11 Watts. Also, when buying the transistor for this project, please make sure you are getting the original Mitsubishi transistor. Most of them which are on e-bay and other websites are Chinese versions and will never give you the same performance.

Parts List:

=> 2x BNC female plugs
=> 2x 80Pf variable trimmers
=> 2x VK200 choke inductor
=> 1x 22 Ohms resistor
=> 1x Mitsubishi 2SC1971Transistor (Datasheet here)
=> 1x 0,02Mf Capacitor
=> 1x 130Nf Capacitor
=> 1x 220Nf Capacitor
=> 1x 1N5400 Diode
=> 1x 10Nf Capacitor
=> 1x 10Mf Capacitor
=> 1x 680 Ohms resistor
=> 1x LED indicator

Below you will find the schematics and pictures of the amplifier. Please click on them to see the full size picture.

Amplifier schematics and pictures:

Due to logical reasons, I have locked these schematics. If you need them please contact me on info@ribamodel-team.com for more information.

1 - FAQ about this project

[Q]: How do I make the spirals that are in this project?
You will need to make 2 spirals with 0.5mm copper wire, 6mm diameter with 7 turns.

[Q]: How do I tune it into my frequency?
You should use a PWR meter.

[Q]: How do I connect this amplifier into my radio?
There are a lot of ways to do it, I personally modified my radio, you can see how on project #003.

[Q]: Do I need a tunned antenna on 35Mhz for this amplifier?
Of course. One way to do it is to mod a CB antenna, like I did on a Santiago 1200CB antenna. See how on project #001.

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