Stout Homebrew Radio Pumps Out 200W Of AM Goodness

In this day and age, with cheap online shopping, software defined radio and bargain-basement Baofengs from China, the upstart radio ham is spoilt for choice. Of course, there’s nothing quite like the charm of keying up your own homebrewed rig, cooked up in the garage from scratch. [Paul], aka [VK3HN], knows just how it feels, and put together an epic 200 watt Class D AM rig to blast his signal on the airwaves.

An example of an Arduino used in one of [Paul]’s builds.
It’s a build following on from the work of another radio ham, [Laurie], aka [VK3SJ]. Younger hackers will note the Arduino Nano at the heart of the project, running the VFO and handling all the relevant transmit/receive switching. We can only imagine how welcome modern microcontrollers must have been to old hands at amateur radio, making synthesizing all manner of wild frequencies a cinch.

The amount of effort that has gone into the build is huge. There are handwound coils for the PWM low-pass filter, and the PCB is home-etched in ferric chloride, doing things the old-school way. There’s also a healthy pile of dead components that sacrificed their lives in the development of this build. Perhaps our favorite part is the general aesthetic – we can’t get over the combination of hand-drawn copper traces and off-the-shelf Arduinos.

Many components perished in the development of this powerful rig.

It’s a build that far exceeds the Australian legal limits, so it only gets keyed up to 120W in real use. This has the benefit of keeping the radio operating far in the safety zone for its components, helping keep things cool and stable. We’re sure [Paul] will be getting some great contacts on this rig. If you’re suffering from low power yourself, consider an amplifer build. Video after the break.

[Thanks to Ben for the tip!]

6 thoughts on “Stout Homebrew Radio Pumps Out 200W Of AM Goodness

    1. Yes AM is quite popular for it’s good sound quality.
      Many of us like to “sound good” on the air.
      For those who are unaware the Hi-Fi on the ham bands do a search on ESSB.
      Hi-Fi SSB has been around for 25+ years.

      1. https://www.w8ji.com/transmitter_splatter.htm

        “Strongly discouraging use of enhanced bass and treble on crowded bands. It has no place on crowded band or near weak signals. Wide-Fi is selfish and inconsiderate even when it uses a 3kHz filter because of the increase in level and frequency spread of IM products. ”

        Couldn’t have said it better myself. HF spectrum is limited. If you want to eat up spectrum with unnecessary fidelity, go up to the microwave bands.

  1. It is not uncommon for people to procure old low power commercial broadcast band transmitters and re-tune them to the 160 meter ham band. A project I would enjoy undertaking someday. They sound really good, and are rated for continuous operation.

    1. Much less common today than 30 years ago. From listening to some of the ‘monologues’ I’ve heard on 75 meters I always imagine a giant, 2 foot knife switch on the far wall of the shack. The OM heaves the switch to the TX position, trudges around the 7 foot steel Gates cabinet and back into his chair to begin his discourse. While his comb over wafts gently in the breeze from the cooling blowers.

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