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Shortwave Resurrection: A Sticky Switch Fix on a Hallicrafters

5 Marzo 2025 at 00:00
Dismanteled Hallicrafters radio on workbench

Shortwave radio has a charm all its own: part history, part mystery, and a whole lot of tech nostalgia. The Hallicrafters S-53A is a prime example of mid-century engineering, but when you get your hands on one, chances are it won’t be in mint condition. Which was exactly the case for this restoration project by [Ken’s Lab], where the biggest challenge wasn’t fried capacitors or burned-out tubes, but a stubborn band selector switch that refused to budge.

What made it come to this point? The answer is: time, oxidation, and old-school metal tolerances. Instead of forcing it (and risking a very bad day), [Ken]’s repair involved careful disassembly, a strategic application of lubricant, and a bit of patience. As the switch started to free up, another pleasant surprise emerged: all the tubes were original Hallicrafters stock. A rare find, and a solid reason to get this radio working without unnecessary modifications. Because some day, owning a shortwave radio could be a good decision.

Once powered up, the receiver sprang to life, picking up shortwave stations loud and clear. Hallicrafters’ legendary durability proved itself once before, in this fix that we covered last year. It’s a reminder that sometimes, the best repairs aren’t about drastic changes, but small, well-placed fixes.

What golden oldie did you manage to fix up?

Convert a Cheap Tube Preamp Into A Headphone Amp With Jenny

Por: Lewin Day
28 Febrero 2025 at 00:00

Big-name tube amplifiers often don’t come cheap. Being the preserve of dedicated audiophiles, those delicate hi-fis put their glass components on show to tell you just how pricy they really ought to be. If you just want to dip your toe in the tube world, though, there’s a cheaper and more accessible way to get started. [Jenny List] shows us the way with her neat headphone amp build.

The build starts with an off-the-shelf preamp kit based around two common 6J1 tubes. These Chinese pentode valves come cheap and you can usually get yours hands on this kit for $10 or so. You can use the kit as-is if you just want a pre-amp, but it’s not suitable for headphone use out of the box due to its high-impedance output. That’s where [Jenny] steps in.

You can turn these kits into a pleasing headphone amp with the addition of a few choice components. As per the schematic on Github, a cheap transformer and a handful of passives will get it in the “good enough” range to work. The transformer isn’t perfect, and bass response is a compromise, but it’s a place to start your tinkering journey. Future work from [Jenny] will demonstrate using a MOSFET follower to achieve much the same result.

We’ve seen a great number of headphone amplifiers over the years, including one particularly attractive resin-encased example. Video after the break.

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