Sunday, May 17, 2015

Download this show wins IT journalism "best audio program" award

Marc Fennell does everything on this show, producer, presenter, interviewer, editor, music mixer and talent wrangler. All credit to the new generation of tech-savvy media stars. It's a privilege to be a very small small part of the show.


Congratulations mate!

Friday, May 15, 2015

Very low cost i2c LCD interface board

Listening to the marvellous Soldersmoke podcast I learned of these serial interface boards for driving an LCD display using just two pins of an Arduino. These boards are just $1 out of China on eBay. Amazing.

With some help from Brainwagon I was soon up and running.


The little board solders nicely on to the back of standard Hitachi LCD boards.


I'm stunned that China can manufacture stuff like this for such great prices. Everything I make will have a display.

SM1000 FreeDV in a box arrived

Very excited this week when the SmartMic 1000 arrived. This is a FreeDV digital voice codec in a very nice box. It's designed so you can hold it in your hand rather like a big microphone and just talk in to it to transmit and receive digital voice.


The case has 3.5mm sockets for everything and also an RJ45 socket for a single cable connection. It's like the Signalink boxes and has a similar internal jumper system for wiring it. I followed the instructions and quickly had it working with my FT817.




The button marked "select" on the front switches between analog passthrough (so you can hear what the radio hears) and digital mode.

To test transmission, I listen off air and decode with the FreeDV app. My scatter plot looks reasonable I think:

I can hear my voice decoded so the next step is some contacts on 14.236 where I'm listening and calling.

Notes: 
  • Mic Gain control operates in reverse.
  • Select button switches between analog and digital. On power on it defaults to analog.
  • Back button isn't used.
Stephen, VK2BLQ, also has one of these and I was able to receive him on 40m, here's a snippet.



Tuesday, May 12, 2015

80m antenna, take 3

It's tough putting up a decent antenna for 80m. The sheer length involved excludes many amateurs without large blocks of land. My shack is at the back corner of the block and I've had several shots at this.

Mostly I've used an inverted V dipole hung from a large tree at the back of the block, actually in the neighbour's yard, but the legs of the dipole have to make right angle turns and run along the fences. Recently I tried a full length dipole along one side fence line - it transmitted quite well but was very poor at reception.

This week I tried an inverted L. A quarter wave length up as far as I can go in the tree and then pulled sideways and a bit down to a pole on the side fence. Early tests with Mal, VK2BMS, indicate that he's the strongest I've received him and I'm the strongest he's heard me.

An earth stake kindly donated by Robert, VK2ZNZ, provides an excellent earth (particularly with all the recent rain) and the antenna tunes up beautifully.

It may well be that it's all ground wave between our houses, although Mal is running a dipole, but we'll see in the weeks ahead how it goes.

Naturally, I'm thinking of how I can combine my interest in drones with ham radio antennas.

Flying a micro-drone with a video camera attached, here's a closer view of the tree.


Using micro-drones to inspect antennas is actually useful. Here we see the support of the top of the 80m inverted L. Just below you can see my 40m dipole's balun.


When there's not too much wind I can take the drone up quite high.



Saturday, May 09, 2015

Mount Stromlo observatory visit

For my birthday I got to do whatever I wanted and of course a visit to the Mount Stromlo observatory in Canberra was top of the list. It's a striking location and we had a big sky above.


The site was devastated in the fire storm of 2003 and the wreckage is still visible. Melted motors.


Remains of telescope buildings.




It's a striking site that seems mostly to be visited by cyclists who ride up and down the mountain.


Oddly, my daughter who has lived in Canberra for over three years had never visited.

The cafe is closed but there is a display for visitors in the old manager's house that has a nice display including some melted mobile phones from 2003.