The biggest difference between building this and a more modern style analyzer is that you would cut out the log detector and replace it with a digitizer.

Thank you, that is the kind of answer that I was looking for.

Hmm, well, it depends on where your knowledge base is :) Studying electrical engineering wouldn't hurt.

(not complete, but it's a start!) Basics: Math: Complex Numbers, Integration Physics: Wave Mechanics, Oscillators, Energy, Impedance Electrical: Currents, Voltages, Capacitors, Coils Electronics: Semiconductors, Resistors

Semi-Advanced: Electrical: Compensation, Impedance Conversion, Complex Values, Frequencies Electronics: Transistors, Amplification

Advanced: Electrical: Magnetic/Electric Fields, EM Fields, Flux, Conductors/Waveguides Electronics: Filters, Operation Amplifiers, Oscillator Circuits

and further.

When you are able to build and test your own filters and oscillators, then you might pull off building a simple/small SA yourself.

!! But remember: always work inside a shielded environment! Active analog HF circuitry interferes with everything else around you !!

I did not mean 'where do I go to pick up the basics', I think I have those covered. But since there is a critique of this design and I actually rather like it I am wondering what specifically you would do different 'today' because of advances in technology. Obviously the whole thing would be mostly using SMD rather than hole through components and the display would be integrated rather than using an external scope but the design itself is what interests me.