Radio Hacks

1447 Articles

Mastering The Tricky Job Of Soldering SMA Connectors

February 22, 2021 by 22 Comments

There’s a satisfaction in watching someone else at work, particularly when they are demonstrating a solution to a soldering problem you have encountered in the past. SMA panel sockets have a particularly tiny solder bucket on their reverse, and since they often need to be soldered onto brass rod as part of microwave antenna construction they present a soldering challenge. [Andrew McNeil] is here to help, with a foolproof method of achieving a joint that is both electrically and mechanically sound.

The best connections to a solder bucket come when the wire connected to it nestles within its circular center. If this doesn’t happen and a blob of solder merely encapsulates both wire and bucket, the mechanical strength of the solder blob alone is not usually sufficient. The brass rod is wider than the bucket, so he takes us through carefully grinding it down to the right diameter for the bucket so it sits in place and can have the solder sweated into the gap. The result is very quick and simple, but has that essential satisfaction we mentioned earlier. It’s a small hack, but if you’ve ever soldered to a too-small RF connector you’ll understand. For more fun and games with RF connectors, take a look at our overview.

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3D Print Your Next Antenna

February 19, 2021 by 40 Comments

Building antennas is a time-honored ham radio tradition. Shortwave antennas tend to be bulky but at VHF frequencies the antenna sizes are pretty manageable. [Fjkaan’s] 2 meter quadrifilar helicoidal antenna is a good example and the structure for it can be created with 3D printing combined with electrical conduit.

Many people, including [G4ILO] use PVC pipe for the structure, and that design inspired [Fjkaan]. Despite being a bit less substantial, the conduit seems to work well and it is easy to cut. The helical design is common for satellite work owing to its circular polarization and omnidirectional pattern.

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Your Own 11.2 GHz Radio Telescope

February 12, 2021 by 26 Comments

Modern life has its conveniences. Often, those conveniences lead to easier hacks. A great example of that is the rise of satellite television and the impact it has had on amateur radio telescopes. There was a time when building a dish and a suitable low noise amplifier was a big deal. Now they are commodity parts you can get anywhere.

The antenna in use is a 1.2-meter prime focus dish. Some TV dishes use an offset feed, but that makes it harder to aim for use in a radio telescope. In addition to off-the-shelf antenna and RF components, an AirSpy software-defined radio picks up the frequency-shifted output from the antenna. There is more about the software side of the build in a follow-up post. We liked that this was a pretty meaty example of using GNU Radio.

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1938 Radio Has Awesome Dial

February 10, 2021 by 19 Comments

[Mr. Carlson] is truly an old radio surgeon. The evidence? He recently restored an 83-year-old DeForest radio by transplanting an identical chassis from another similar radio. The restoration is fun to watch, but the 7D832 radio dial looks amazing. The dial is very colorful and the wooden knobs and preset selector are beautiful. To seal the deal, the center of the dial has a magic eye tube, giving the radio a retro high tech look.

The donor chassis needed some work before the surgery. In addition, [Carlson] makes some improvements along the way. The radio showed signs of previous service work, which is not surprising after 83 years.

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The $50 Ham: Digital Modes With WSJT-X

February 10, 2021 by 33 Comments

As it is generally practiced, ham radio is a little like going to the grocery store and striking up a conversation with everyone you bump into as you ply the aisles. Except that the grocery store is the size of the planet, and everyone brings their own shopping cart, some of which are highly modified and really expensive. And pretty much every conversation is about said carts, or about the grocery store itself.

With that admittedly iffy analogy in mind, if you’re not the kind of person who would normally strike up a conversation with someone while shopping, you might think that you’d be a poor fit for amateur radio. But just because that’s the way that most people exercise their ham radio privileges doesn’t mean it’s the only way. Exploring a few of the more popular ways to leverage the high-frequency (HF) bands and see what can be done on a limited budget, in terms of both cost of equipment as well as the amount of power used, is the focus of this installment of The $50 Ham. Welcome to the world of microphone-optional ham radio: weak-signal digital modes.

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3D Printer Makes Ham Antenna Portable

February 9, 2021 by 8 Comments

You don’t normally think of a 3D printer as a necessity for an antenna project. However, if you are interested in making a handy portable antenna, you might want to melt some plastic. [N2MXX] has an end fed antenna winder design that also contains the necessary matching toroid. This would be just the thing to throw in your backpack for portable operation.

The end-fed configuration is handy for portability too, because you can easily secure one end and feed the other end. Compare that to a dipole where you have to feed a high point and secure both ends.

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The Last Few Analogue TV Stations In North America

January 29, 2021 by 40 Comments

Analogue TV is something that most of us consider to have been consigned to the history books about a decade ago depending on where in the world we are, as stations made the transition to much more power and frequency efficient digital multiplexes. However some of them still cling on for North American viewers, and [Antenna Man] took a trip to Upstate New York in search of some of them before their final switch-off date later this year.

What he reveals can be seen in the video below the break, an odd world of a few relatively low-power analogue TV stations still serving tiny audiences, as well as stations that only exist because their sound carrier can be picked up at the bottom of the FM dial. These stations transmit patterns or static photographs, with their income derived from the sound channel’s position as an FM radio station. While his journey is an entertaining glimpse into snowy-picture nostalgia it does also touch on some other aspects of the aftermath of analogue TV boradcasting. The so-called “FrankenFM” stations sound much quieter, we’re guessing because of the lower sound carrier deviation of the CCIR System M TV spec compared to regular FM radio. And we’re told that there are more stations remaining in Canada, so get out there if you still want to see an analogue picture before they’re gone forever. Where this is being written the switch to DVB was completed in 2013, and it’s still a source of regret that we didn’t stay up to see the final closedown.

Does your country still have an analogue TV service? Tell us in the comments.

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