One of the great things about ham radio is that isn’t just one hobby. Some people like to chit chat, some like to work foreign countries, some prepare for emergencies, and there are several space-related activities. There are hundreds of different kinds of activities to choose from. Just one is moonbounce, and [Ham Radio DX] decided to replicate a feat many hams have done over the years: communicate with someone far away by bouncing signals from the moon.
The set up is pretty sophisticated but not as bad as you might imagine. You can see that they spend a lot of time getting the equipment aligned. A known reference point helps them set the position of the antenna. A GPS keeps both stations in sync for frequency and time.
Ham radio, especially the HF bands, can be intimidating for aspiring operators, many being put off by the cost of equipment. The transceiver itself is only part of the equation and proper test and measurement equipment can easily add hundreds of dollars to the bill. However, such equipment goes a long way to ease the frustrations of setting up a usable station. Fortunately [Ashhar Farhan, VU2ESE] has been at it again, and recently released the Antuino, an affordable, hackable test instrument for ham radio and general lab for use.
As you can probably guess from the name, it is primarily intended for testing antennas, and uses an Arduino Nano as a controller. It has quite a list of measurement functions including SWR, field strength, cable loss, RF cable velocity, modulation, and frequency response plotting. It also provides a signal source for testing. Its frequency range includes the HF and VHF bands, and it can even work in the UHF bands (435Mhz) if you are willing to sacrifice some sensitivity. The software is open source and available with the schematics on Github.
Most of the active ham radio operators today are of the grey haired, retired variety. If the hobby is to stand any chance of outliving them, it needs to find a way to be attractive to the younger generations who grew up with the internet. The availability of affordable and hackable equipment can go long way to making this happen, and [Ashhar Farhan] has been one of the biggest contributors in this regard. His $129 μBITX HF SSB/CW transceiver kit is by far the best value for money general coverage HF radio available.
See a short demonstration of the Antuino video after the break
You might have to provide your own wrist straps and eye clamps, but if you want to learn Morse code, [Seth] has a web site for you. You can get code practice using the Farnsworth method and each letter is flashed before you as it is sent, which we assume will burn it into your brain.
Why learn Morse code now? Just about all countries now have at least some no code ham licenses and many have taken code off the tests completely. However, there are still many hams that use the code even today. Why? The personal challenge is part of it and perhaps nostalgia. However, it is also true that Morse code transmitters and receivers are dead simple to build and can get through where other simple radios can’t.
It is sort of the American dream: start a company in your garage and have it get crazy big. After all, Steve Jobs, Bill Gates, and even Bill Hewlett and Dave Packard did it. Seems hard to do these days, though. However, one ham radio company that has been pushing the edge of software defined radio appears to be well on the way to becoming more than its roots. FlexRadio has teamed with Raytheon to undertake a major project for the United States Air Force.
The Air Force has given Raytheon and FlexRadio $36 million to develop an HF radio based on the existing SmartSDR/Flex-6000. ARRL news reports quote FlexRadio’s CEO as saying that the investment in the military radios will pay dividends to the firm’s ham radio customers.
We usually think of the RTL-SDR as a low-cost alternative to a “real” radio, but this incredible project spearheaded by [Rodrigo Freire] shows that the two classes of devices don’t have to be mutually exclusive. After nearly 6 months of work, he’s developed and documented a method to integrate a RTL-SDR Blog V3 receiver directly into the Yaesu FT-991 transceiver.
The professional results of the hack are made possible by the fact that the FT-991 already had USB capability to begin with. More specifically, it had an internal USB hub that allowed multiple internal devices to appear to the computer as a sort of composite device.
Unfortunately, the internal USB hub only supported two devices, so the first order of business for [Rodrigo] was swapping out the original USB2512BI hub IC with a USB2514BI that offered four ports. With the swap complete, he was able to hang the RTL-SDR device right on the new chip’s pins.
Of course, that was only half of the battle. He had a nicely integrated RTL-SDR from an external standpoint, but to actually be useful, the SDR would need to tap into the radio’s signal. To do this, [Rodrigo] designed a custom PCB that pulls the IF signal from the radio, feed it into an amplifier, and ultimately pass it to the SDR. The board uses onboard switches, controlled by the GPIO ports on the RTL-SDR Blog V3, for enabling the tap and preamplifier.
Somehow [hvde] wound up with a CB radio that does AM and SSB on the 11 meter band. The problem was that the radio isn’t legal where he lives. So he decided to change the radio over to work on the 6 meter band, instead.
We were a little surprised to hear this at first. Most radio circuits are tuned to pretty close tolerances and going from 27 MHz to 50 MHz seemed like quite a leap. The answer? An Arduino and a few other choice pieces of circuitry.
Software-defined radios or SDRs have provided a step-change in the way we use radio. From your FM broadcast receiver which very likely now has single-application SDR technology embedded in a chip through to the all-singing-all-dancing general purpose SDR you’d find on an experimenter’s bench, control over signal processing has moved from the analogue domain into the digital. The possibilities are limitless, and some of the old ways of building a radio now seem antiquated.
[Pete Juliano N6QW] is an expert radio home-brewer of very long standing, and he’s proved there’s plenty of scope for old-fashioned radio homebrewing in an SDR with his RADIG project. It’s an SDR transceiver for HF which does all the work of quadrature splitting and mixing with homebrewed modules rather than the more usual technique of hiding it in an SDR chip. It’s a very long read in a diary format from the bottom up, and what’s remarkable is that he’s gone from idea to working SDR over the space of about three weeks.
A block diagram of the N6QW SDR
So what goes into a homebrew SDR? Both RF preamplifier, filters, and PA are conventional as you might expect, switched between transmit and receive with relays. A common transmit and receive signal path is split into two and fed to a pair of ADE-1 mixers where they are mixed with quadrature local oscillator signals to produce I and Q that is fed to (or from in the case of transmit) a StarTech sound card. The local oscillator is an Si5351 synthesiser chip in the form of an SDR-Kits USB-driven module, and the 90 degree phased quadrature signals are generated with a set of 74AC74 flip-flops as a divider.
Running the show is a Raspberry Pi running Quisk, and though he mentions using a Teensy to control the Si5351 at the start of his diary it seems from the pictures of the final radio that the Pi has taken on that work. It’s clear that this is very much an experimental radio as it stands with wired-together modules on a wooden board, so we look forward to whatever refinements will come. This has the feel of a design that could eventually be built by many other radio amateurs, so it’s fascinating to be in at the start.
If I and Q leave you gasping when it comes to SDR technology, maybe we can help.
