Stuart VK2FSTU has found an neat step-by-step article detailing how to create a 2m repeater with a raspberry Pi – Anton ZR6AIC writes:

I will be using a rtl dongle to receive my input signal on 70cm frequency configurable on the amateur 2m or 70cm band.  The receiver signal will then be demodulated and retransmitted with a DSP Library simulating a FM Signal using a GPIO pin on the Raspberry as an transmitter.

As mentioned above, the project interestingly uses a GPIO pin on the Pi as a transmitter with attached antenna (which is certainly novel, but not exactly high power!).  Note the article is quite technical (as you’d expect).

Check out the article here and have a look at the video demonstrating it in use below: