A Band Switching Game Changer - National's “Movable-Coil Tuning Unit”

ln the mid 1930s James Millen and the National Company, Inc announced an innovation called the “Movable-Coil Tuning Unit”. The first of these “coil-catacomb” or “sliding-coil” receivers was introduced in 1936 and represented the first truly high-performance communication receivers that did not use plug-in coil sets. This receiver series continued to evolve and expand through WW2 and beyond with the addition of direct-reading dials and a single unified band-change and tuning control system. By 1949 over 60 different receiver variants had been manufactured and many of these show up at swap meets and hamfests usually at very reasonable prices.
Antique Wireless Association Member and communications historian Brian Harrison, KN4R, tells the story of these revolutionary receivers in this presentation from the AWA Shares series.
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[@awiles79]

What a phenomenal series of videos on National radios! Thank you so much for your efforts in making these videos available for us! I learned so much.

[@lvstofly]

Hello fellows, Im a noob tuber. Found a 48 lb Galena crystal for my first radio build. Made a 6' untuned catwisker out of some transmission power line ground wires. Soldered some wires into a hole for at least one solid connection. I am still working on my antenna. Will post video soon. Thanks for all you guys do.

[@mackfisher4487]

21:40 The Frequency Meter front left, a MARZ buddy used it in the 60s to be sure net operations were on the correct frequency. With kindness I call it a boat anchor it's huge and weighs a ton, heat coming off of kept his basement warm. Anyone know the nomenclature?

[@mackfisher4487]

What would be the reason for removing a data tag, (data plate) from the radio or piece of equipment? I just don't understand why one do that.