Reading through the various SOTA doco on the sota.org.uk sites, I felt it was missing one key element. A simple documenting the steps for getting started – ie. your first chase/activation.
Thankfully in VK land, Andrew Davis (VK1DA/VK2UH) has come to the rescue with yet another great addition to his VK FAQ.
I highly recommend if you’re keen to get started in SOTA and you’re after some good concise info – with links out to all the other stuff – then you can do no worse than visiting Andrew’s Summits of the Air section of his FAQ. I especially point you to the section titled ‘What next? How do I join in?’ – as that’s what I’ve found lacking on the official SOTA sites.
Found some nice transistor tutorials by AllAmericanFiveRadio that seem to be reasonably well put together.
First is one on some biasing basics:
And another still a bit on biasing, but more so on small signal amplification:
One thing I took from this was that it’s good to just get out there an experiment with transistors. It’s one thing to first learn all the theory, but sometime some good ol’ hands on can be useful. I need to go and have a play.
I’ve been busy plugging away at my DDS/Arduino/VFO for 630m (more on that later), however yesterday I came across a neat little circuit for a code practice oscillator.
Cheaper Beeper CPO
I’ve still got my previous CPO, however the simplicity of this one appealed to me. It’s two transistors, two resistors and a capacitor. All on a small piece of perf board.
In the image above, you can see the 9V battery connector. At the bottom are the two wires for audio out. And then in the middle there will be two more wires for the cw key. My plan it to mount it all in a small box with two 3.5mm mono ports – one for audio out and one for the key. That way I can either feed the audio into my computer for practice or into a speaker.
I’m thinking I may still build another CPO yet, as I really would like one with a sine wave – the square wave is a bit harsh and annoying. Plus, one with a sine wave I could wire into my FM rig for some code sending practice – if I find someone else so equipped. (I think sending the tone of these guys over the air would probably drive me and my practice partner nuts – not to mention anyone listening!)
Anyway, if you’d like to build one of these little guys yourself, the instructions can be found online here at the ARRL website. However, a word of caution.
There is a minor error in the schematic. If you’re rushing through trying to build the thing up quickly after work it may bring you unstuck – as it did to me. The PNP transistor in the schematic is marked as a 2n3904, however it is in the parts list as a 2n3906. Now a quick check would show that the correct one is the 2n3906, but if you just look at the schematic and go barging in blindly, well it wont work.
Anyway, enjoy! If you build one up send me a photo! 🙂
Sacrificial transistor – should’ve checked.
This is an interesting and informative video on a home built 4-bit computer using discrete components to demonstrate the theory.
It’s presented at a rapid pace, so it’d be great to pause and take bits in and really understand them. But I’ll add that to the list.
Back in April I linked to Peter’s (VK3YE) video on minimal QRP – it required a small back pack. He’s now taken it further with his little 100mW 40m CW rig and has a setup that essentially fits in his pockets (other than a squid pole).
Owen Duffy (VK1OD) has produced yet another useful calculator on his website. This calculator makes it very easy indeed to evaluate power levels of your radio gear with your oscilloscope. Section 7 in 'Experimental Methods in RF Design' details measuring your power with a 'scope and provides the formulas you need. However, with this calculator you can make your measurements with your scope, and then just plug the numbers in and get your answer – couldn't be easier.
Enjoy! Thanks Owen!