Practical Radio Circuits (2003) [pdf]
fracassi.net
fracassi.net
I do have an RF design book I haven't started (by Chris Bowick) as well as this PDF now, which should be even more practical, so I'm hopeful I can figure it out. I also have some test equipment such as nanoVNA, tinySA, and an oscilloscope which makes it possible to get visibility into how stuff behave beyond "I don't hear anything; no idea what's wrong." I was able to see how the tank circuit was behaving as you tune it.
The Bowick book is solid for fundamentals like impedance matching and basic filter design. The old brown edition is more concise than the new one.
Cool, I do have the ARRL handbook (100th edition). I also got the 50th (1973) and 66th (1989) editions partly out of curiosity (for the 1973 one) and because someone told me a late 80's edition might be good for info about building stuff.
[1] https://www.worldradiohistory.com/BOOKSHELF-ARH/Technology/M...
It's also trivial to reverse all the polarities in the circuits and switch to NPN. Use a positive supply voltage rather than negative, flip the rectifier diode around as well as all the electrolytic caps.
I didn’t believe it until I tried it, but it’s a surprisingly good first pass at an FM frontend.
A sound card with a true 192Khz sample rate should be enough to fool a radio clock next to the transmitter coil - though be aware a lot of sound cards may not actually output the 60kHz carrier frequency required.
Used to be easy to pick up Loran signals in the same way (esp. with untuned aerials) but they're all turned off now.
Many RF transistors are no longer available in through-hole though you can probably find small quantities for hobby projects. The msph10 is long gone. And good luck sourcing dual-gate mosfets even in smt. Infineon might still make a couple.
As a digression, it does make me think TRF receivers are probably a better learning tool than the my-second-radio regenerative receiver. Crystal radios, of course, are pure magic and it’s sad that so few people get to build them as kids.
Pair it with the Gemini protocol and you're there: https://en.wikipedia.org/wiki/Gemini_(protocol)
And you can do encryption, when you have to control remote devices which belong to you.
and internet still can be non commercial.
The actual rules say you're not allowed to obscure the meaning of a message. Use of encryption itself is not specifically prohibited, but you're not allowed to hide the information being sent. So, "encryption" is technically allowed for things like authentication and signatures, under most interpretations of the rule.
It is correct that you're not allowed to use your ham license for any commercial purpose. But again, there are narrow exceptions: a teacher getting paid to teach a class on amateur radio or science in general can transmit to demonstrate the technology, or an astronaut or military member making contacts with amateurs for goodwill purposes or as part of an exercise.
There are plenty of other anything-goes bands for you to use, there's literally no reason to do your pirate radio on the ham bands. Except to get those warm fuzzy counter-culture feels I guess.
That said, balancing this with modern needs for security and privacy is a real challenge. Good communication protocols today are designed with these protections in mind, and the inability to use encryption arguably limits what amateur radio enthusiasts can do with newer radio technologies.
Privacy, however, has traditionally not been part of ham radio—this is why you’re required to identify yourself with a call sign, and contact info is publicly available. The identity of the sender is expected to be open. Maybe there’s room to allow for some privacy around the content of the message itself, but the sender’s identity should still be clear. I’m not sure what the right balance is, but simply allowing complete encryption that hides the message, the transmitter’s identity, and the transmission protocol itself doesn’t seem to align with the purpose of amateur radio.
The ‘trash bands’ (ISM bands) are probably a much better place for experimenting with full-bore encryption and privacy. From these experiments, we might learn a balanced approach that could be backported to the amateur spectrum, preserving the spirit of why these bands exist while adapting to modern privacy needs.
If you want to add some illegality to the system, you could piggyback on amsats or open relay satellites like FLTSATCOM to expand your network and hide better.
For hiding you'd be able to use actual DSSS with e.g. AES encrypting a suitably fine grained clock piggybacking on GPS as a time reference, keyed by a shared secret. Then just hone in with e.g. a Costas loop like a GPS receiver does to it's satellites (where the sequence is sourced from a simple clocked logic circuit that's cheap and offers better than random spreading gain at the cost of being cryptographically useless) and demodulate the payload the same way.
You could start off at GPS synchronous sequence generator timing, and slowly shift it at increasing delay until lock in is archived or an implausibly long implied travel distance (signal loss!) is reached (then you can give up and start over, go to sleep and try later, etc.).
i don't think this would be in and off itself a game changer but it could be a seed for further development of anarchistic technology culture.