Homebrew ladder line spacers

It never ceases to amaze me what wisdom is simmering away amongst those email discussion groups I read.

Out of the blue today – prompted by mention of a commercial solution on the Elecraft list – came a sequence of brilliant ideas about making effective and easy on the budget ladder line spacers.

The commercial spacers from K&S Ham Radio Parts look great, but the fact they’re made of nylon prompted concerns about their survival against UV. At 25 cents a piece I think they look fine!

In response there was a pointer to a YouTube video showing how to turn a box of ballpoints into very neat and secure spacers using black cable ties.

And then a pointer to another commercial solution from True Ladder Line, and a hint about how to replicate the effect at home using ‘drip sprinkler tubing’ which is the right size and and has just the right amount of rigidity for the job. And there’s Dave ZL1BJQ with his approach based on those plastic chopping boards you can buy at any $2 shop, cut into spacer pieces, notched then pushed on to wires and held in place with hot glue.

Spacer
Spacer

And then there’s this approach by VK2YE using plastic coat hangers, cut to length (5cms) and drilled to fit wire, and then glued to stay in place. In fact this is just one of 138 videos on his YouTube channel.

WSPR

Prompted by Julian G4ILO’s musings about the possibility of volcanic ash being responsible for propagation he observed a few days back, I’ve been looking deeper into WSPR, the application that produced the data that inspired the notion.

First stop was the main WSJT site where Princeton physicist Joe Taylor K1JT outlines the application along with other weak signal communications applications. The WSPR page points to the 20pp. User’s Guide (pdf).

There’s also some information at the WSPRnet site – especially the stunning map and the detailed database of recent spots.

Map of WSPR contacts
Map of WSPR contacts

Full circle – when I searched for a general introduction to the software and the mode it’s based on – sure enough I end up back with Julian, G4ILO. He’s published a very readable and comprehensive article which quite rightly comes up #4 on a WSPR google search. He describes how easy it is to become part of a global beacon network and contribute to the generation of up-to-the-minute propagation reports.

Right now, I’d really like to know how to interpret the colour and thickness of the lines tracing the transmission paths on the map.

FT-817 resources online

There’s a wealth of digested experience on this particular radio online.

ka7oei has a detailed site which has pages devoted to the following topics:

Yaesu's FT-817 transceiver
Yaesu’s FT-817 transceiver

Other FT-817 related sites include:

One of G4ILO’s ‘Radio topics’ pages is devoted to the FT-817. His document points to 817-Mem, a program to manage memories on the radio.

A123 batteries

There’s been a great explanation posted on the Buddipole list about the practicalities of using the A123 battery packs Buddipole sell from their site.

A123 4S2P battery
A123 4S2P battery

The advantages of the A123 chemistry are low weight, fast charge times and ability to deliver high current. As well their voltage – 13.2v for a four cell pack such as the one shown – is well-suited to modern amateur radio gear.

The email exchange is yet another example of how an innocent newbie’s question can draw out the best information which benefits the broader group. Mark KD5RXT’s explanation of duty cycle and the unique qualities of this new battery chemistry are almost text-book ready!

I’m still keen to find out more about the selection of the best solar cell and charger system to keep such a battery topped up. I sense that a system that could take advantage of its fast charge rate might dwarf the rest of the radio gear. And I also sense that current portable solar panels, especially the expensive roll-up ones might barely keep track even at QRPp levels.

iPad date announced for Australia

News this morning from Apple that the delivery date for iPad (both WiFi & 3G) – in Australia – is 29th May.

The new Apple iPad
The new Apple iPad

I’m so looking forward to seeing how an iPad might fit into a portable QRP operation. Or even a remote one. I’m also hoping that Apple will retain enough of open protocols so that the device does not simply become an expensive personal front end to whatever shops they wish to set up, like the sadly not ready for primetime Kindle.

Lack of a camera on the iPad is odd – given the next iPhone will actually have two – one in the front as well as the existing one on the back. Bluetooth keyboard sounds like it could be fun. I also imagine that ham radio apps to track satellites (ProSat) and monitor solar activity (Space Wx, 3D Sun etc) should look amazing. A work colleague showed me his new Android phone with a graphically brilliant astronomy application that you could use to locate, stars, planets and constellations easily. It felt like visual velvet and the images were much richer than I’ve seen so far on the iPhone.

Even a straighforward app to display bandplans should be able to be made to look clear and brilliant and enable you to get different views depending on mode, QTH or licence class.

The creator of the Continental code

Friedrich Clemens Gerke
Friedrich Clemens Gerke

I stumbled on to a page on Wikipedia about Friedrich Clemens Gerke, (22 Jan 1801 – 21 May 1888) the man responsible for simplifying Vail and Morse’s original telegraphic code.

As the wikipedia article explains, “The original Morse code consisted of four different hold durations (the amount of time the key was held down), and some letters contained inconsistent internal durations of silence. In Gerke’s system there are only “dits” and “dahs”, the latter being three times as long as the former, and the internal silence intervals are always a single dit-time each.”

This chart reveals the logic behind his reform of the code.

Gerke's tree chart of letter codes
Gerke’s tree chart of letter codes
After some minor changes it was standardised at the International Telegraphy congress in Paris in 1865.

Fabric antenna

Via Southgate News and MAKE magazine news of a collapsible fabric yagi antenna developed by Diana Eng KC2UHB who has combined two craft skills in a stylish way, electronics and sewing. It’s a design for a Yagi for portable amateur radio satellite operation.

Diana Eng KC2UHB demonstrates her collapsible fabric yagi antenna
Diana Eng KC2UHB demonstrates her collapsible fabric yagi antenna

Her MAKE magazine article is well-written, comprehensive and brilliantly illustrated.

Diana Eng has also written an earlier article aimed at newcomers to amateur satellites for MAKE that covers:

  • Finding out when to listen
  • Finding the frequency
  • Aiming a whip antenna
  • Following the pass with the antenna
  • Tuning the radio for the Doppler effect

Check the size of the antenna in that earlier piece and you’ll understand why she aimed at something more portable!