My wife and I just soldered together the MK 118 FM radio. It works, sort of. I would like to understand how it works, on the level of being able to explain the function of each of the components we assembled and design a similar circuit. Where should I start? Are there design notes for the MK 118 somewhere?
Sorry, there are no circuit descriptions available.
This is a basic application of an FM front-end, TBA120U/V5 IF demodulator and LM386 amplifier.
Basically, the FM front-end is a black box which is fed an adjustable DC voltage, to be able to tune between 88 and 108 MHz.
The output is fed into the TBA which converts the FM signal to an audio signal. This signal is amplified by the LM386.
You might want to Google for TBA and LM datasheets, they contain useful information and application examples.