Yeah I’d read that. I could probably paraphrase the definition the ARRL handbook gives for most of these terms and concepts but after that I lack a lot of knowledge to do much with it.
There is a decently sized digital kingdom/playground where as long as you respect the laws of the land you can build with a vast array of simple to interconnect, cheap, powerful components. Yes to make it all work there is a minority of engineers that master the analog domain to maintain the digital illusion.
For everything I call a “0 to 1 edge” is a product of a complex cascade of non-ideal transistors with an equivalent circuit themselves, maybe ESD protection, and even more beyond what I know. But the results of the complicated analysis of those systems are summarized in the laws of the land: regulate voltage supply, respect limits of I/O currents, voltage, clock speed, wire impedance, load impedence, etc. a non exhaustive list, not saying digital circuit design is easy either, just that it has a finite number of of these rules/limitations to follow and if you do then a simplified model works within those bounds. The majority can work within these bounds because of the minority who can design components or solve problems for the applications that need to push the bounds.
Maybe my terminology was mixed up again. It’s not the fundamental principles that are mostly relevant to the previous generation, it’s the vintage electronics built with a small number of discrete, mostly throughhole soldered or socketed components. Easy to map schematic to physical circuit, easy to probe, add components in parallel, swap, replace. Seems ideal for learning the fundamentals. Downsides, seems there is lots of knob turning, on setup, periodic maintenance, and during operation, adjustments as things warm up or components age. Modern electronics seem to not have as many nobs, presumably many of the knobs can be replaced by algorithms possibly performing better than a human would anyways. The previous generation part is mastering knob turning and splicing in analog circuitry for signal processing.
At an individual hobby level I have a somewhat humble outlook: there’s only specific areas within any given domain where DIY effort can produce anything effectively. Maybe I could build a shed better in some ways than the pre assembled one at the hardware store, but I’d still buy nails and screws from the store not try to manufacture them myself. So the analog front end part of radio feels like a something that is more effective to just buy the mass produced output of a talented R&D and focus on learning about antenna installation and operation.
A related question, what is a recommended responsible beginners access to test equipment (beyond multimeter and oscilloscope) and test procedures to be proficient with? NanoVNA was mentioned, anything else you would add to a toolkit to prepared for real-world likely encountered problems that need to be addressed (design problems, equipment failure, installation mistakes, operator errors)?
A good multimeter, preferably with true RMS calculation, and a simple 2-channel oscilloscope are very helpful tools. If you plan to be messing with constructing your own transmitters, you will require a spectrum analyzer with a useful bandwidth of at least 5x your highest frequency of interest. If you’re not interested in circuit building or antenna construction, you won’t need a soldering iron, but if you plan to do any of those things, repair or troubleshoot gear, or even assemble DIY kits, you might want to invest in at least a decent soldering iron and some stuff to practice with if you’re not already skilled and equipped in that area.
But it sounds like your interests lie further afield than the DIY side of things, so you may want to take all that with a grain of salt and just get, as @milfox said, a HackRF or some other SDR platform and play with the tools those offer. SDR interests me, but only a little, so I can’t make any recommendations on that front, but @milfox may have some more info on the tools available there.
That said, quite a lot of the SDR toolkits out there are HF oriented, so you might want to be sure any SDR you want to play with is able to do frequencies you’re licensed for.
Depends on if you want xcivers or receive only - besides the hackrf or anything based on a rtl-sdr(recieve only) - this might be a good source to start with. Hardware - GNU Radio
At the moment I am pretty content trying to see what’s out there and learn the communication protocols better, I would likely be entertained for a while with receive only. So far the only thing I can listen to reliably is a weather report. Last night there were a few weekly nets, at least there were at one point. 2 out of 3 I could not hear, for the last one my baofeng began to blare static. when I picked it up, the static at least changed and eventually walking around I found a place to hold it where I could sort of hear over the static. So by necessity I am now interested in antennas.
Spent some time trying to navigate the SDR space, leaning towards the hackRF still despite it having far from the best performance for use as a dedicated ham rig according to most comparisons I found. The biggest appeal is the documentation.
Does frequency of interest refer to the frequency one intends to operate at, or the highest harmonic that could be unintentionally transmitted?
You want a spectrum analyzer to be less than 3dB down in the analogue domain (and below the unit’s Nyquist frequency in the digital, these are two separate specifications) at the fifth harmonic of the highest frequency you are operating at plus any modulation which extends the bandwidth of your signal. The fifth is a rule-of-thumb minimum. For some digital modes higher harmonics may be inherent and you’d need to consider that on a case by case basis.
To expand: in most cases the amplitude of harmonics decreases with order, sometimes the even set are stronger (so the 4th is lower than the 2nd but they are both higher than the 3rd and 5th etc), sometimes the odd set is, and sometimes you have a waveform or modulation scheme that generates, say, really strong seventh harmonics only. But usually, regardless of whether the odd or even orders are stronger, there’s a decreasing trend with higher order. So five is usually enough to see the pattern clearly and know how much energy is likely to be in higher order harmonics. Usually.