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A project log for PUZZLE: radio building blocks

Or how to build a HF transceiver and learn along the way!

M.daSilvaM.daSilva 02/27/2017 at 16:410 Comments

I'm tired of using black boxes. When I started the hobby, I had the idea of building equipment, antennas, and such. However, when the ticket arrived, laziness crept in; I bought my antennas, my transceivers, etc... I had became some would refer as an "appliance operator"! Of course I built some stuff, DDS frequency controllers, computer/rig interfaces, portable antenna+tuners, ... But custom-built rigs always seemed extremely complicated, and I guess that kind of held me back from breaking it down to their simple components.

(KX0R's multiband superhet rig. Although an amazing build, I need to start with something simpler before even dreaming to understand how this is built.)

Then the Bitx40 kit came out. Designed by Ashhar Farhan aka VU2ESE, this board can receive and transmit voice on the 40m (7MHz) band, for 59$! When you know how much a modern SSB transceiver costs, even nowadays, it's extremely cheap. I started studying the schematics, the extremely well laid-out board, and very quickly recognized which part of the circuit did what.

(Bitx40 board, pic taken from http://blog.marxy.org/2016/11/pre-built-bitx40-review.html )

One of these kits is on the way; I'm sure I'll have lots of fun playing with it. However, I don't want to stop there, I feel like this transceiver could be easily modified: change the IF frequency, turn it into a biband/multiband transceiver, ... As I don't want to risk ruining this nice board, and I want to learn some more, I'll respin my own! To help me understand how each block works and interacts with the others, they'll be divided into units I can play with individually.

Considering the price of custom PCBs today, this seems to be a sound decision.

I'm not an expert on that matter, I'm really hoping to learn more about RF design, how amplifiers behave, how significant impedance matching is, along with some other things!

I feel like the hobby has more to offer for me, off to make something more involved!

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