Adventures in QRP

 I've been slowly getting my QRP portable station together. Just before having brain surgery I bought an mcHF QRP radio kit from M0NKA (not a clone or Chinese built rip off). My idea was to build it while recovering from the surgery as a way to prove there was no lasting damage. Things did not go quite to plan and only now some 3 years later am I finishing the radio. Along the way I lost some of the parts including the knobs and the rubber buttons. It also didn't quite work when I gave it a test drive.

Suspecting shoddy workmanship on my part I went back over my work. As far as I could tell it was all good. In conversation with the gang over on the mcHF mailing list it was suggested to me that it might not be my work that's at fault and to check the factory installed components too (the kit comes with many surface mounted parts pre-soldered). Following the alignment procedure I was able to track down the issue to the band pass filter arrangement. I again checked that I had wound the filter coils properly and that they were connected to the PCB. I then progressed to the pre-installed relays that switch the various filters off and on. BINGO. Dry joints abound. Re-flowing the relay's solder joins with my iron yielded a working radio.

I was able to buy some rubber buttons for the radio via eBay but not the knobs. Owning a 3D printer is often a bonus in situations like this. A quick search on thingiverse.com revealed quite a large collection of parts for this radio that I could print including some knobs. That problem is now solved. I later printed a matching tuning knob so that all the knobs are the same colour.

But what about an antenna? In the end I decided to build this one from a radio club that's based in Hawaii. Its a simple end fed random wire antenna with a 9:1 transformer to help with the matching.

This really was a junk box build. I recovered the iron core from an old UPS that my employer was throwing out. In its previous life the core was part of the 24-120V inverter circuit. I was even able to reuse some of the wiring from the old UPS to wind the transformer onto the core.

Again, my 3D printer was pressed into service. Trolling through Thingiverse.com again I was able to find an enclosure for this part of the project. I added 35 feet of speaker wire that was kicking around and was able to complete the project with other supplies form my apparently well stocked junk box. The only thing I had to buy was #6-32 nuts and bolts. They were just $1 at the local WalMart.

Here's a video of me testing the whole setup from the parking area at the back of my apartment building. 

I have this LiFePO4 battery which is about half of the weight of other lead acid batteries of the same size. Plus, its LiFePO4 technology which will actually save me money in the long term as I'll get more life from it. 

I think I'll be printing this carrier for the battery too.

Crypto mining on an Arduino

Yes. You read that correctly. Crypto mining on an Arduino.

I recently discovered something called Duino Coin. It's a proof of concept crypto currency. But unlike other currencies where you need massive mining rigs to produce just a few $$$ before you pay for the electricity and hardware, this one uses very modest micro processors. In fact if you use higher end hardware to mine this coin you get a penalty and the reward drops significantly.

I'm using a method called I2C mining. This is where a handful of miners are connected together via an I2C bus and then another device handles the connection to the network. Very similar in setup to a traditional rig where a load of graphics cards are plugged into a PC. 

You cannot buy hardware for this project and so I designed my own circuit board. It uses common off the shelf parts. 5x Arduino Nano's (ATMEGA328), 1x Wemos D1 (ESP8266) and a power supply (MP1584). The D1 handles the WiFi connection and the communication with the Arduino's. The Arduino's do the actual mining.

This is what I came up with and it works very well. Each miner gets about 250 hashes a second.