Edit:  Think I'm getting the hang of it now.
I have some decent understanding of the transmitter and amplifier circuits I've looked into. At least I think I do ;)

Not quite sure about the receiver, any recommendations in that regard?

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I'm new to this, and currently looking to gain a better understanding on how the whole circuitry works.

Now, I'm aware that there are some extremely simple devices, like the Mighty Mite transmitter and Pixie.
However, as far as I understand, these seem to be little more than novelty toys, due to very low output powers.

What I'm looking for is something inbetween these, and the more "fancy" devices, like the Mountain Topper, with a 3+ bands and a microprocessor plus firmware, and so on.

Something to tinker with, see where each part belongs, and figure out why it belongs there and what it does.

Closest thing I've found so far would be this: https://www.qsl.net/kd7rem/5wpa.htm

A compact, comprehensive transmitter, with the fitting amplifier to make it more useful.
However, the whole site is rather light on instructions.

Is there anything to that effect that'd be more suitable for beginners?