After looking around, I decided on the Elenco AM/FM radio kit as a learning platform.
These can be had retail for about $50 and for $20 or so if you are pleasant when you send an offer on eBay. Looks like eBay has the packages intended for educational use.
While it does start the builder off in the right direction, you need to be self directed to get full use out of it as a learning platform. For example, you are told to measure emitter resistor voltages without telling you why the value should be what it is. Time to pull out network theory.
Lots of learning time on modulation, scope use, sig gen use, transistor theory (if you dig into it), etc. Of course, LC ckts and resonance. The build time was not long, but I spent two weeks by the time I was done exploring. Even learned about emitter junction resistance (inverse of transconductance).
It does share some of the faults of the ThaiKit Curve Tracer. For example, I could not get the supplied LM385 to stop oscillating. Replaced it with a second one I had on an Arduino module, better, but not fixed. I did notice the oscillation was reduced when I applied heat with the heat gun. SO I learned some things there, but replacing it with a genuine LM385 fixed the issue.
Since I wanted to do the analyses, I recorded the "as installed" resistor values. Their resistors were generally OK; but their caps are horrible. Also, I finally saw a youtube where the presenter had many of the same issues I encountered. But he added that the tuning cap could be destroyed by too much heat.
He also explained that the .01 uF cap between the sig gen probe and the ckt was to keep the 9VDC out of the sig gen. This was not explained in the kit manual.
The provided test points are crap. I used single header pins and Dupont jumpers to connect the sig gen.
In the end, the AM radio is not very useful. AM is all but dead and the antenna is not great. BUT, it did fill my goals. I did read about coupling antennas to improve reception but in my area the AM band is either religious or political. SO that part is done.
I will go on to the FM section this winter.
In the meantime, is there a list of kits or projects that yield useful things? Not Arduino kinds of stuff, stuff that can advance a beginners understanding of fundamentals while building something "practical".