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.

GL-INET AR750 conversion to 5VDC

I own one of these Travel Routers. It's great for connecting multiple things to the single Internet feed in a hotel room or camp site. The problem is that it uses a USB power supply and if one does not use the correct cable the router becomes unstable. This is due to the voltage losses in the thin wire used in cheap USB cables. The router is quite thirsty and so requires a cable that can deliver a good half an amp.

GL.INET AR740 Travel Router

I want to use this router for camping. I want to have this router be the Access Point that my phone and laptop and TV connect to. In turn this router will connect (usually by WiFi in WISP mode) to whatever Internet I can find. To this end I need to power it from my 12V camping batteries or solar panels.

One of the optional extras for this router is a Power Over Ethernet (POE) board which will take the 48V from your POE capable network switch and convert it to the 5V needed to power the router. 

POE Adapter

I opened up the router and found the pins that would receive the 5V from the above POE board. This discovery was greatly helped by the below picture that I found on the manufacturers website.

Now that I have established how to connect 5V to the board I need to come up with a 12V to 5V DC-DC power supply. Luckily Amazon is full of them. For a previous project I bought some LM2596S variable DC-DC power supplies. These are available from all the usual online places such as Amazon and Ebay for around $1 each.

LM2596S DC-DC "buck boost" converter.

A word of warning; before connecting this power supply to your Router (or Raspberry Pi etc) make sure to set the output voltage to whatever you need it to be.  This can be achieved by connecting your power source to the input then turning the screw on the variable resistor (the blue block thing) whilst measuring the output with a volt meter. I set mine to 5.02V.

Next was a session with my 3D printer to create an enclosure. Thingiverse.com was my friend here. However I had to print a second power supply case as the lid to the first one would not fit. The capacitors on the board were too tall to allow the lid to fit.

DC-DC converter in 3D printed case

Time to test it all. I wired the power supply into the router and gave it an initial "smoke test". No smoke was observed this time. Everything seemed to work as expected.

DC-DC power supply connected to the router

DC-DC power supply and router wired together

All wrapped up with in their respective cases

The final step was to install in onto the electrical board that I use when camping. The board holds the solar charger, fuse board, 110V inverter and battery charger. This seemed like a logical place to install the router as power is available right there. I also installed the POE injector for a TP-Link WiFi bridge with high gain antenna that can be remotely placed (for example, on my portable radio mast) to bring in the WiFi signal from further afield should it be needed. 

Router installed on power board

A quick trip to my local WholeFoods Market (where they have free WiFi) was made to test the whole system. It worked flawlessly. Here are some screen shots from the test tools I used.

Some IC-7300 pics ...

I bought Harbor Freight "pelican" style case for my Icom IC-7300. The radio can now get dragged around in the back of the car and taken camping etc without fear of damage.

FT-817 Go Box

I've had this kicking around for a while. Before I put it up for sale I thought I'd show you all my FT-817 Go Box.

It's built around a Harbor Freight "pelican" style case and contains everything needed to operate the radio in any mode. Just add a battery. The photos are pretty self explanatory.

Ham Radio Clock for Raspberry Pi

In a previous post I discussed building a clock to display the grey line and times zones on a large screen. Thanks to this project I've been able to improve the display as well as reducing the cost by a further $65.

The finished clock running on a 5 Inch LCD screen on the Raspberry Pi3

This clock originally appeared in a QST article in October 2017 but it took me a while to get around to it.  Whilst trying to get some "shacksessories" organised for my wife, KM4WSK's new radio shack I remembered it. I also happened to have a RPi3 connected to the Official Raspberry Pi 7" LCD and associated enclosure so I installed the software onto that.

The clock application installed into Official Raspberry Pi 7" LCD

As you can see, the clock displays not only the greyline but also solar weather data, sunspots, local weather data, UTC time and the current state of the HF Beacon transmissions. It's also able to display the path of a few satellites too.

Whilst I had all the parts for my wife's clock I was lacking an enclosure for my 5" LCD screen. A quick search on Thingiverse.com revealed a case that I could print on my 3D printer and then mount onto the wall. 

First boot of the clock. Note the lightning bolt

At first boot of the 5" display I was confronted with the dreaded lightning bolt. This is an indication that there is insufficient current available to properly drive the RPi and associated hardware. It's a simple fix requiring a bigger PSU. KM4WSK was able to supply a larger one from her seemingly bottomless "junque" box.

I've decided to revisit my large clock on the LCD TV (the one from the previous article). To this end I've temporarily mounted my 5" version on the wall. With a few crontab entries I can turn the display on and off so as to save energy overnight.

Fiberglass pole/mast repair

Many hams buy sets of these military surplus 4' fiberglass poles for use as portable radio masts. They are lightweight, easy to deploy and store well in the back of the car. But there's a reason that they are surplussed out from the military; they are mostly split at the bottom.

Typical split in a fiberglass pole

Over time these splits will get larger and larger. Eventually the pole will fail under stress and the mast will collapse. This will most likely happen right when you are passing that vital piece of information to the Net Control station after that tornado tore through your neighborhood and you are the only station left on the air.

My set of poles suffers from this problem. So I have made some minor repairs to mitigate the inevitable loss. I have a bracket that holds the bottom of the mast. It's about 8 inches tall and so can well support the worst damaged pole. I always use the worst damaged one at the bottom.

The worst pole gets put at the bottom where there is most support

Then using a hose clamp I secure the other poles such that they can no longer splay out. Do not tighten the clamp too tight as you'll misshape the pole. You simply want to add to the structural integrity. If the cracks are too bad you can drill a hole right at the top of the crack to prevent it from moving further up the pole. I stole this trick from the Liberty Bell 😁

Add a hose clamp to the damaged pole

Finally, assemble the poles in the usual manner. 

2 "repaired" poles seated together

In addition to the repairs I added an eye bolt to the very top pole so that I can attach an antenna wire to it.

Eye bolt installed for wire antenna. HSMM-Mesh adapter also installed.