Tuesday, December 10, 2019

The Nano VNA- a handy RF test instrument

Something that's hit amateur radio antenna experimentation by storm in the last 6 months or so is the availability of very small and very cheap vector network analysers. Previously considered expensive test equipment, they are now within reach of (and can be put in) every pocket. 

They are a bit clunky to use and their user interface isn't great (especially if you have fat fingers). And they won't be as accurate as expensive gear. However they open up a world of measurement that amateurs with a non-professional electronics background did not necessarily have. 

Use as an antenna analyser is an example application. You could also try connecting anything that exhibits varying reactance across different frequencies, for instance coil and capacitor combinations. 

Anyway if you've just got one or are about to take the plunge then these video resources could be handy. 







PS: I've now written six books on various aspects of amateur radio. Whether you experiment with antennas, enjoy QRP or are starting out in radio there's a book for you. Find out more here.

Monday, December 9, 2019

Pedestrian mobile on 28 MHz

The rest of Australia was sweltering but yesterday was nice weather here. So I went for a 5km walk along the beach, taking 10 metres with me. The video shows what I worked during the good conditions.



PS: Find hints and tips for working DX in Minimum QRP. It's the top-selling manual on the equipment, antennas, operating and strategy of successful QRP operating. And its techniques work for 100 watts as well. It's available for under $US 5 each in electronic form. Or you can get a paperback version. Visit VK3YE Radio Books to find out more. 

Friday, December 6, 2019

Decoding FT8 with a simple 3 transistor receiver and laptop computer.

About 8 years ago, before the FT8 mode was invented, I built a simple receiving converter. When used with a laptop computer with SDR software it could receive signals on segments of the 80 and 40 metre amateur bands.

It was very crude. For example there was no image rejection. Therefore signals on the lower side of the centre frequency would also appear above (with inverted sideband) and vice versa. Anyway yesterday I got it out to see how it would work on FT8. It did! More in this video!



PS: Find hints and tips for working DX in Minimum QRP. It's the top-selling manual on the equipment, antennas, operating and strategy of successful QRP operating. And its techniques work for 100 watts as well. It's available for under $US 5 each in electronic form. Or you can get a paperback version. Visit VK3YE Radio Books to find out more. 


Thursday, December 5, 2019

Sights and sounds of a local Maker Faire

On Sunday I went to a Maker Faire not far from here. This video is some of the highlights. Yes, there are still lots of people doing things with electronics! 



PS: Heard about my new book? It's the Australian Ham Radio Handbook. It's now available both as an ebook and paperback. Find out more here!

Wednesday, December 4, 2019

Four crystal super VXO pulls 5 kHz higher

Those who tinker often like to squeeze the best performance out of their creation. It might be accelaration or fuel economy from their vehicles, output power from a linear amplifier or gain from an antenna. 

Something else in this category is pulling range with a variable crystal oscillator (VXO). Normally they can only be shifted by a few kilohertz. However there's ways, from keeping capacitances down, adding series inductance to using parallel crystals, that extend pulling range. The cnallenge in this case is to maximise pulling range while keeping your signal acceptably stable. And pulling above a crystal's marked frequency can be harder than pulling below it. 

This video is of a VXO experiment.  I use 7.023 MHz crystals, a frequency commonly supplied with the cheap 'Pixie' QRP transceiver kits. 


Have you ever built a VXO? What pulling range did you get? Please let me know in the comments below. 

PS: Find hints and tips for working DX in Minimum QRP. It's the top-selling manual on the equipment, antennas, operating and strategy of successful QRP operating. And its techniques work for 100 watts as well. It's available for under $US 5 each in electronic form. Or you can get a paperback version. Visit VK3YE Radio Books to find out more. 

Tuesday, December 3, 2019

50 MHz QRP with various modes

This time I'm at home using about the most modest antenna you can get - a vertical dipole for 50 MHz (which doubles as an extended double zepp on 2m). I try various modes on 6m with 5w from an FT817. Very happy with the results. 


And for more on the antenna enjoy this video. 


PS: I've now written six books on various aspects of amateur radio. Whether you experiment with antennas, enjoy QRP or are starting out in radio there's a book for you. Find out more here.

Monday, December 2, 2019

27 & 28 MHz listening with a portable receiver

Some weekend listening to 27 MHz CB & 28 MHz amateur activity. Signals were heard from up to about 1500km distant. I was using a small Digitech HF receiver capable of SSB reception.


PS: Heard about my new book? It's the Australian Ham Radio Handbook. It's now available both as an ebook and paperback. Find out more here!





Sunday, December 1, 2019

Working VK4s while 28 MHz pedestrian mobile

Northern hemisphere readers are going into winter while us down here are entering summer. Which brings more daylight to be out and about plus enhanced sporadic-E propagation. Yesterday was a great example with sporadic E all the way up to 144 MHz. 

Video shows me out and about on 28 MHz SSB working various stations up to approx 1500km distance.



PS: Want to learn about portable antennas? You'll find many ideas and projects in the top-selling Hand-carried QRP antennas.






Saturday, November 30, 2019

A frequency agile 7 MHz FM exciter

People don't often build FM gear on HF. It takes up a wider bandwidth than SSB and is less efficient. But it is very simple. This video discusses how you can generate FM signals on 7 MHz with two transistors. 


PS: Find hints and tips for working DX in Minimum QRP. It's the top-selling manual on the equipment, antennas, operating and strategy of successful QRP operating. And its techniques work for 100 watts as well. It's available for under $US 5 each in electronic form. Or you can get a paperback version. Visit VK3YE Radio Books to find out more. 

Friday, November 29, 2019

Building a sliding variable capacitor

Have some spare kitchen foil and some plastic pipe? Why not make a sliding variable capacitor from it? This video shows how.



PS: Want to read more about antennas? Consider this selection of antenna books. They are affiliate links meaning that I receive a small commission (at no extra cost to you) if you decide to purchase.

    

Thursday, November 28, 2019

Building a trap dipole for 7 and 14 MHz

I'm not a huge fan of trap dipoles. They work well enough but with room for only a few antennas I prefer to get several more bands out of them. Nevertheless if you're happy with a couple of bands then one can be a good project. And there's no antenna couplers to twiddle, unless you operate near the edge of the antenna's bandwidth. 

Anyway here's a video on one for 7 and 14 MHz to enjoy. I did it a few years ago but it continues to be popular. 


PS: Many other antenna topics are covered in Hand-carried QRP Antennas. Available in electronic and paperback form (some countries) this well-reviewed book is a popular read amongst hams who go portable.

 Link to find out more about Hand Carried QRP Antennas

The Nano VNA- a handy RF test instrument

Something that's hit amateur radio antenna experimentation by storm in the last 6 months or so is the availability of very small and v...