Tuesday, December 31, 2019

Very simple bi-quad antenna for 432 MHz

A very simple antenna for the 432 MHz (70cm) band. Can be built in minutes but provides a little gain. Not as good as a beam but worthwhile for casual SSB and WSPR work.


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. 


Monday, December 30, 2019

Ask me anything Q & A

The first Q & A for a few months. Lots of discussion on antennas, QRP, homebrew etc. Have a listen!


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



Friday, December 27, 2019

28.490 MHz and 10m activity

First part of this new video is mainly of interest to VK viewers as it discusses our unofficial SSB calling frequency of 28.490 MHz. Second part demonstrates a few pedestrian mobile contacts made on (and off) the beach. 


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


Tuesday, December 24, 2019

A ham's night before Christmas

From the ARRL


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 23, 2019

28 and 50 MHz dual band fan dipole

My latest video. Simple antenna does 28 & 50 MHz at once with no switching.


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

Friday, December 20, 2019

[EEV Blog video] Near Field and Far Field explained

A video worth watching from EEV Blog explaining near and far field.

Applicable for RF work and EMC compliance testing.


PS: Do you sometimes come across terms that you're unfamiliar with? The Illustrated International Ham Radio Dictionary can help. Available in both ebook and paperback it's great value. Find out more here


Thursday, December 19, 2019

Testing a parallel tuned circuit

A quick video where I make a tuned circuit (for around 50 MHz) and test it. Firstly with a noise source and receiver and then with a Nano VNA. Tuned circuits have many applications in radio including antenna traps and receiver front ends. 


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.





Wednesday, December 18, 2019

The bi-quad antenna

Some tyes of antennas are used in other facets of radio but don't commonly find their way into the ham world. One of those is the bi-quad. It's basically two quad loops in parallel but configured so it looks like a bow tie (vertically polarised version). They're most common for 2.4 GHz wi-fi work where they can be made from a piece of wire soldered to an antenna connector. A reflector behind gives some extra gain and directivity. If you have a little more room there is such a thing as a double bi-quad (4 squares instead of 2) for even more gain. 

You can make one from wire for 70cm if you scale the dimensions up. My own quick experiments have been promising though there's far less activity here on 70cm (especially digital modes) than 2m. 

Anyway here's some links to follow up if you're interested. 




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 17, 2019

6 & 10 metre portable telescopic dipole antenna

Here's another portable antenna to try. It uses a pair of TV rabbits ears. Because what I had didn't spread out to a very wide angle, I removed them from their holders and attached them to a piece of plastic chopping board. And because they were only 1m each long I added some loading to allow operation on 50 MHz (which needs about 1.35 to 1.4 m length each). 

Then more turns were added to give 28 MHz operation. This makes sense because 28 MHz is normally open when 50 MHz is and overall there's more activity on 28 MHz. So if you move the coil tap you get a portable dual band antenna. 

The video describes it a bit more and demonstrates a 1000km plus SSB contact on 28 MHz. You could likely get more bands by adding more turns but efficiency will gradually fall. This design is a good option for 27 MHz CBers looking for something they can take portable but which folds up to a small space. 



Would I use it in preference to the loop I already have for 28 & 50 MHz? Probably not. Not because performance is lacking but because it's a bit unwieldy to use while walking around.  

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

Monday, December 16, 2019

G4ZU's 'Jungle Job' antenna

This is an antenna I'd like to experiment with but haven't got around to it. It's basically a two element beam. The reflector is straight while the drive element is V-shaped. This is potentially a handy way of getting a bit of gain on bands like 10 and 15 metres. They seem to have been most described by European hams. 

Some links here: 

G4ZU website (G4ZU is a silent key and his antenna work is summarised here)





If you've made one please let me know how it worked. 

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

Saturday, December 14, 2019

How plugged in but not switched off appliances can cause RF interference

A quick video where an unexpected noise source that interfered with 28 MHz reception was identified. Watch to find out more! 



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.


Friday, December 13, 2019

What is ham radio? (ARRL video)

Want a quick video to show someone whose expressed an interest in amateur radio? Here's one from the ARRL.



PS: Want to read 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, December 12, 2019

Buy lots of ferrites and fit them to everything

The reason why is in 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.

Wednesday, December 11, 2019

4 ways to know when 28 MHz is open

No apologies for more on 28 MHz as the band's been open a lot lately. While sporadic-E mainly happens in the summer there is also a smaller burst in winter. So northern hemisphere folk can join in the fun.  

This video gives some tips on how you can find out when the band is open to avoid missing out on the action. 



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!





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

Wednesday, November 27, 2019

Losing most of your signal: Tests with lossy coax cable

You might have a good transceiver and efficient antenna but station performance will be poor if your feedline is not up to scratch.

Here's a video where I attempt to measure loss with various lengths of RG58 at various frequencies with various pieces of test gear.





PS: Want to support The Daily Antenna
You won't be charged extra and I'll get a small cut from any purchases you make (affiliate link). You can buy lots of stuff there, including electronic parts and my books.

Monday, November 25, 2019

28 & 50 MHz portable dipole

We've had this one before but if you don't have one now is a good time to build one.

Here in the southern hemisphere we're approaching our peak time for sporadic-E propagation.

Both 10 & 6m will produce long distance contacts and strong signals.

Even a simple dipole like this is good for many enjoyable contacts.



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. 

Light pole antenna and crystal set (video)

At mentioned yesterday I've been doing experiments with a light pole antenna and a crystal set.

Here's the video arising from it.

The audio is from holding the headphones up to the camera with no amplification.

In practice it's much louder than you'd here on the 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.

Sunday, November 24, 2019

More light pole antenna tests (with a crystal set)

OK so maybe some are still skeptical about my light pole antenna tests on 160m. I won't say much here as a video is coming soon but they also work really well as a receiving antenna on the AM broadcast band. How do I know? I used it with a crystal set and got great volume into unamplified headphones. 

The proviso is that impedance matching must be excellent. You can't just hook the 20m perimeter loop to the crystal set's antenna and earth terminals and expect good results. I used my loop antenna coupler. Tuning is a bit finnicky with its controls also selecting the station in conjunction with the crystal set's tuning capacitor but it does make a big difference. My coupler only goes down to about 1100 or 1200 kHz but the strongest station on 1377 kHz comes in well as do some others. 

Anyway the results were excellent so look out for the video. 

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

Saturday, November 23, 2019

How long can an FT817 operate with 8 x AA NiMH batteries?

I normally use external batteries with my FT817.

Those supplied in the Yaesu battery pack were only 600 mAH.

And even those in the FT818's pack have a bit more capacity but not quite enough.

Anyway the video here documents my experiences with 8 NIMH batteries purchased from IKEA.

They're low self discharge rechargeables.


PS: Want to read 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.

    

Friday, November 22, 2019

Filing ceramic resonators

Ceramic resonators are handy parts for the radio tinkerer. They can be shifted in frequency much more than crystals by adding series capacitance and/or inductance.

Here's an attempt to shift frequency by other means - by filing. These two videos describe how I did it.






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 21, 2019

What you're most interested in

A housekeeping type post. What topics are Daily Antenna readers most interested in?

The answer's pretty clear. Many of you are QRPers interested in new gear. My thoughts on the IC705 got almost twice the viewership of any other item.

Antennas feature prominently because for a while that was the only topic covered here. Those for small spaces are very popular. For example apartment HF antennas and magnetic loops. Maybe it's because you're more likely to be on the web than on the air if your antennas are limited?

There's also a fair interest in VHF/UHF antennas. Three of the top 10 posts are in this category.

Anyway you can see all the top 10 below. It will help me think of things to write about.


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.

Wednesday, November 20, 2019

Bidrectional wire beams - tests on 28 MHz

Further to yesterday's post, here's a video of a test I did with signals from a local beacon on 28 MHz. I compared a vertical dipole on its own with a 2 element beam, firstly with a reflect then with a director. Watch the video to hear the comparison. 



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.

    

[Article] Batteries for QRP gear

The March 2020 issue of QST has an article on batteries for QRP rigs that some of you might find interesting.  Even better is it's...