Special
Signals

The Model E is one of Atwater Kent's early external speakers — a large-format cone driver in a cast iron open-back frame with an ornate Gothic quatrefoil grille in bronze. The cast iron base is period-correct, and the whole assembly has the heft and presence of something built to last a century. It has.

In the mid-1920s, radio receivers had no built-in speakers — audio came out of a headphone jack, and if you wanted to fill a room, you attached an external horn or cone speaker. The Model E represents that era exactly: a time when the radio itself was a technical marvel and its speaker was a piece of furniture. This one dominates any room it occupies, which is entirely appropriate for a piece of equipment that was meant to announce the arrival of broadcasting to an astonished public.

The M-600 is a standalone hardware decoder that processes non-voice signals — Morse, Baudot RTTY, ASCII, and TOR — and outputs decoded text to a video monitor and/or printer. It connects to the audio output of any communications receiver. No computer required; the intelligence is entirely in the box.

Decodes Baudot RTTY at 45–132 WPM, ASCII at 75–1200 Baud, TOR (ARQ and FEC), and Morse from 5 to 120 WPM with auto-ranging. Features a 10-step LED bar graph for tuning, bit-inversion scanning across all 32 possible combinations, and a sel-cal selective calling system. The screen-print feature allows the operator to capture anything currently on the video display directly to the printer — a paper saver, and a handy way to pull hard copy after the fact.

I used equipment like this during my time in the Navy — the M-600 is a less versatile version of the M-8000, which I did some pretty good work with. It takes audio out of the receiver and does that little black box magic to turn those beeps and squeaks into actionable intelligence on a good day. These decoders are not classified, and can be found fairly often. I found this one on Goodwill.com. You'd use something like this to process the teletype FSK signals that send the feeds you see in Operations — a fitting role for a piece of gear that spent its life turning signals into useable content.

Any radio collector worth their salt has at least one tube checker, and the IT-21 is a fine one to have. The BAD/GOOD meter with its color arc tells you immediately what you need to know — no ambiguity, no guesswork. Filament, plate, leakage, emission: the IT-21 covers the essentials with the characteristic Heathkit thoroughness.

An eBay acquisition, and worth every penny. Before powering up any restoration project, the tube checker gets consulted first. It has likely saved more tubes from the trash — and more radios from silence — than any other tool on the bench.

Found in the corner of a garage at an estate sale in North Augusta, SC — the radios on offer that day turned out to be junk, but this was not. Heavy, olive drab, and unmistakably military. The AN/GSC-T1 is a self-contained Morse code training system: multiple keysets, audio output, and a flashing light output for silent practice. Built to work in any theater, under just about any conditions. It still does.

There is a particular satisfaction in owning this one. As a Navy signals operator I copied Morse code at a high degree of proficiency throughout my career. As a Navy Tech School instructor, I taught it. This machine trained the hands that sent the messages that mattered. Finding it in a garage while looking for something else entirely felt like it was supposed to happen.

Not a radio — a speaker, and a good one. The R-42 was Hallicrafters' matching external reproducer, designed to pair with their communications receivers and give the audio the room it deserved. It works with any receiver, but it's the Hallicrafters name on the cabinet that makes it something special — the same olive-and-black metal finish, the same no-nonsense construction, the same sense that it was built to be used.

Found at the Stone Mountain Hamfest. It pairs naturally with the rest of the Hallicrafters stable, and in a signals room setup it completes the picture: receiver on the desk, reproducer alongside, headphones on the hook. Everything in its place.

The S-200 was Hammarlund's matching external speaker for their HQ-series communications receivers — the HQ-110, HQ-170A, and HQ-180A all in this collection. The grey two-tone cabinet with its woven grille cloth and period badge is a direct visual echo of the receivers it was designed to sit atop, turning a functional accessory into a considered piece of industrial design.

A well-chosen external speaker makes a genuine difference in communications reception — pulling audio out of the receiver chassis and into a proper enclosure changes the character of the sound entirely. The S-200 does exactly that.

The NC-2TS is the factory-matched external speaker for the National NC-2-40D receiver — same charcoal hammertone finish, same chrome trim strips, same rubber feet, same cabinet proportions. National built the NC-2TS to be the NC-2-40D's companion, and together they form a matched set that looks as deliberate as it sounds.

Finding a matching speaker for a pre-war receiver is considerably harder than finding the receiver itself. The NC-2TS is a rare piece, and having it paired with the NC-2-40D here completes one of the collection's most historically significant stations.

This is a vintage, fully functioning "The Rex" operator headphones, produced by Trimm Radio Mfg. Co. (later Trimm Inc.) of Chicago, Illinois, during the early to mid-20th century. Designed for high-impedance applications like telephony and early ham radio, they feature circular Bakelite earpieces, a minimalist twin-wire adjustable headband, and a classic braided cloth cord terminating in a metal-tipped plug.

While similar in appearance to military-grade headsets from the same era, this specific model was a staple for commercial and civilian radio operators due to its sensitivity and durable construction. This headset was an "Easter egg" find inside the Montgomery Ward Airline desk radio (elsewhere on the site).