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. 

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.

    

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.

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? 

Please start your Amazon shopping here. 

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.

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.

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.

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.

    

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.

    

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.

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.