A very pleasant Ham Radio day. My friends Joel and Mark (VK5QI) visited my home to build Peter Parkers (VK3YE) “Porta 40″ DSB receiver (from the November 2012 issue of “Amateur Radio” magazine). Joel did the assembly work, with Mark and I helping test the receiver.
We started with the local oscillator, . . . → Read More: My First FreeDV Contact
I recently helped out debugging the Wifi on another AR2317 router project. This is the same SoC chip as the Mesh Potato, so I was revisiting the same Wifi debug territory as 18 months ago.
Turns out this board had the same major bug as we found in the Mesh Potato – the reference clock crystal . . . → Read More: Microwave Design and Why Experience Matters
After my success with the Flower Pot antenna on 2m I was inspired to try the same antenna design on the 40m (7MHz) Ham band. At HF frequencies, my ARRL handbook calls this design a Resonant FeeD line (RFD) antenna.
I used the dipole formula of antenna length equals 143/f meters where f is the . . . → Read More: Resonant Feed Line Antenna for 40m
In Part 4 I managed to get a micro-controller based DC-DC converter running. To ring a telephone we need a 20-50Hz sine wave of about 100Vpp superimposed on -48VDC. In other words a ring signal that moves between 0 and -100V.
The DC-DC converter set point can be programmed in software, for example -48V for . . . → Read More: $10 ATA Part 5 – Ringing a Phone with a DC-DC Converter
For the $10 ATA I want to design a DC-DC converter using a micro-controller and a few discrete components. However, this means some sort of control system, i.e. a feedback loop that includes the “the plant” (the thing we want to control):
I admit I am intimidated by control system design. I studied this at . . . → Read More: $10 ATA Part 4 – Building a DC-DC converter with a microcontroller
This project has been asleep since 2007 when I published Part 1 and Part 2 of the $10 ATA series. However for a couple of reasons I was inspired at lca.conf.au 2011 to go back to work. So for the past few weeks I have been working on this project for a few hours . . . → Read More: $10 ATA Part 3 – Hybrid
I am getting back into Ham Radio, inspired by the incredible response to the Codec 2 project from the Ham community. In my home office, I had trouble listening to the local 2m repeater due to all the high speed digital kit I have. So I decided to put up an external antenna.
Through the . . . → Read More: Flower Pot Antenna and Wifi Sleeve Dipoles
A few day ago my son William and I helped out with the launch of Horus 14 – a high altitude balloon that made it to the edge of space. These near space balloons reach an altitude of 30-40km, about 3 times the altitude of regular jet aircraft. At that height the horizon is . . . → Read More: Horus 14 – Tux in (near) Space
A few years ago I installed an Air Stream node at my house. Air Stream is a community wireless network here in Adelaide. Unfortunately my link stopped working after a while as the node I was linked to moved. So last Sunday a team of Air Stream guys descended upon my house to . . . → Read More: Air Stream Kilkenny Part 2
For the last few days I have been helping Atcom debug the V1.3 Mesh Potato – this is the prototype of what will be the production Mesh Potato. Note the two printed omnidirectional antennas at one end of the PCB:
It also sports an integrated FXS port (this was a separate module on the . . . → Read More: Mesh Potato V1.3