Most new houses are part of homeowners associations, covenants, or have other restrictions on the deed that dictate what color you can paint your house, the front door, or what type of mailbox is acceptable. For amateur radio operators, that means neighbors have the legal means to remove radio antennas, whether they’re unobtrusive 2 meter whips or gigantic moon bounce arrays. Antennas are ugly, HOAs claim, and drive down property values. Thousands of amateur radio operators have been silenced on the airwaves, simply because neighbors don’t like ugly antennas.
Now, this is about to change. The US House recently passed the Amateur Radio Parity Act (H.R. 1301) to amend the FCC’s Part 97 rules of amateur stations and private land-use restrictions.
The proposed amendment provides, ““Community associations should fairly administer private land-use regulations in the interest of their communities, while nevertheless permitting the installation and maintenance of effective outdoor Amateur Radio antennas.” This does not guarantee all antennas are allowed in communities governed by an HOA; the bill simply provides that antennas, ‘consistent with the aesthetic and physical characteristics of land and structures in community associations’ may be accommodated. While very few communities would allow a gigantic towers, C-band dishes, or 160 meters of coax strung up between trees, this bill will provide for small dipoles and inconspicuous antennae.
The full text of H.R. 1301 can be viewed on the ARRL site. The next step towards making this bill law is passage through the senate, and as always, visiting, calling, mailing, faxing, and emailing your senators (in that order) is the most effective way to make views heard.
At some point you’ve decided that you’re going to sell your wireless product (or any product with a clock that operates above 8kHz) in the United States. Good luck! You’re going to have to go through the FCC to get listed on the FCC OET EAS (Office of Engineering and Technology, Equipment Authorization System). Well… maybe.
As with everything FCC related, it’s very complicated, there are TLAs and confusing terms everywhere, and it will take you a lot longer than you’d like to figure out what it means for you. Whether you suffer through this, breeze by without a hitch, or never plan to subject yourself to this process, the FCC dance is an entertaining story so let’s dive in!
Continue reading “Preparing Your Product For The FCC”
[VK2ZAY] has a thing for 555 chips. Before the ready availability of microcontrollers, the 555 was the hardware hacker’s swiss army knife. After all, even though the chip is supposed to be a timer, it is really a bunch of simple pieces you can use to make a timer: a pair of comparators, a few transistors, and a flip-flop. You can use those parts in many different ways, and a timer is just one of them.
[VK2ZAY] used one as a key component in a simple spectrum analyzer. The 555 generates a ramp voltage which alters the frequency of an oscillator. The oscillator mixes with the input signal and a fixed-frequency superregenerative detector creates an output voltage proportional to the input signal strength. You can see a video of the whole setup, below.
Continue reading “Spectrum Analyzer With 555 Fits In A Tin”
[George Trimble] likes to build crystal radios. The original crystal radio builders used high impedance headphones. In modern builds, you are as likely to include a powered amplifier to drive a speaker or normal headphones (which are usually around 4 to 16 ohms).
[George] builds his own speakers using chile cans, some wire, a few magnets, part of a Pepsi can (we are pretty sure someone will leave a comment that Coke cans sound better), and the iron core out of an audio transformer. You can see a very detailed video of the process, below.
There is a little woodworking and hot gluing involved. The result is decidedly homemade looking, but if you want to say you built it yourself (or, if you are a prepper trying to get ready to rebuild after the apocalypse and you can’t find a cache of headphones) this might be just the ticket.
Most of the headphone hacks we see start with a pair of headphones. That’s a bit tautological, but the goal is usually to add features, not make the whole thing. It does give you some hacker cred, though, to be able to look at the other guy’s radio and say, “Oh. I see you used commercial headphones.”
Continue reading “High Impedance Headphones? They’re In The Can!”
[AA7EE] is no stranger to building radios. His latest is a from-scratch build of a 20 meter QRP transceiver based on the popular SST design. Although the SST has been available as a kit, [AA7EE] incorporated some design changes from others and some of his own, too. He even added an onboard keyer to simplify operation. You can see videos of the radio below.
The build uses Manhattan-style PCB pads. Although the construction is very attractive, the real value of the post is the detailed explanation of not only how, but why everything is the way it is. This isn’t a simple project, and being able to see it completed step-by-step is very educational. About the only decision not adequately explained was the change of red and yellow knobs to black! You can see both versions in the videos below.
The Manhattan construction is tidy, but the radio also has an attractive case. The size is just big enough to stack a pair of paddles on top.
There may be some more enhancements for the little radio coming. We’ve covered [AA7EE’s] RF exploits before, including a physically attractive radios and details about the same construction method used in this radio.
Continue reading “Wilderness Radio Build”
When you think of a crystal radio, you probably think of something simple maybe built out of household scraps. Not if you are [Chris Wendling]. He recently posted a video (see below) of his high-performance crystal set. He doesn’t take any shortcuts: he has several hundred feet of antenna wire, and uses a cold-water pipe ground system. With no amplifier, a strong signal input is crucial.
The radio has four subsystems: an antenna tuner, a bandpass filter, a detector, and a powered audio output system. He also has a truly enormous system of speakers on the ceiling–this isn’t the crystal radio you made in the boy scouts.
Continue reading “High Performance Crystal Radio”
We all use 74 logic in our projects as general purpose logic interfacing glue. These chips have become as ubiquitous as a general-purpose op-amp, or even as passive components. In most cases we’re not demanding much of them, and power requirements aside an original 74 chip from the dawn of the series could probably do the same job that we’re putting a more modern variant to work on.
It is easy therefore to forget that 74 logic is a field that has seen continuous improvement and innovation reflecting the developments elsewhere in electronics, and the most modern 74 versions hide some impressively high specifications.
A good example comes via a project from [Scott, AJ4VD], a very simple frequency counter that uses a single 74 series chip at its business end, and counts to over 100MHz. The chip in question is a 74LV8154 dual 16-bit counter which he is using as a prescaler to deliver a rate more acceptable to an ATMega328 microcontroller that does the counting. As he points out, the accuracy of a frequency counter is only as good as its gate timing, and he ensures as accurate a seconds-worth of pulses as he can with a 1PPS signal derived from an inexpensive GPS receiver. The 328 makes its counting available to a host computer via a serial port, and can be easily read through a terminal. He’s built it dead-bug style on a piece of unetched PCB, on which the simplicity of the circuit is evident.
There was a time when a project like this one would have required multiple integrated circuits including a probably quite expensive purpose-built prescaler. Cheap glue logic has now advanced to a stage at which it can be done instead at commodity prices, and we like that.
We’ve featured a few 74-series counters before, including this old-school one and this one also using a 74LV8154.