Successful Linear Amplifier Firmware Hack

A mentally arduous week finally paid off.

I had been burning through the past week trying to hack the firmware on a HAM radio amplifier. The problem is there are many interlocks on it, and one interlock (gain too low) caused it to trip constantly when attempting to power a Tesla coil with it.

I took the amplifier apart to find a PIC32MX processor, and next to that was what looked like a plain ICSP header…..

So against better judgement I plugged it into the computer and successfully dumped the firmware to a .hex file.

The next week was a process of attempting to disassemble+decompile the code into assembly, then

Then began the mapping and tracing and testing breakpoints against the amplifier.

Over 500 thousand lines of undocumented raw assembly code, and 350 functions.

In the end, the fix was changing an 8 to a 2 in exactly the right place.

Next up is just putting everything back together, and finally getting back to the Musical Tesla Coil project

Probably some champagne first though 😉

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