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Therapeutic Radio, by Marek Klemes
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Proud Canadian and RF Cafe contributor Dr. Marek Klemes wrote to me a couple weeks ago regarding a quotation I had posted a while back. At the end of our communications, he casually made a comment about needing to engage in an electronics project that would be free of the rigors of his professional pursuits. Being a trained notable quote recognizer myself, I instantly realized that his statement was itself worthy of being quoted widely. He granted permission to post it here (with adornment of the original). Per Marek in part:
Dig the amazing 1930s vintage Magnavox gramophone speaker bearing a manufacturing location of Oakland, California, and the Canadian Brandes Ltd headphones of the same era. A hand-drawn schematic / wiring diagram can be seen in the lower photo*. The oscillator appears to be a simple Hartley tapped coil type, and the antenna is a section of 300-ohm twin lead feeding a folded dipole. A 3A4 pentode vacuum tube is the lone amplification / detection device, which uses two series-connected 'D' cells to light the heater. The mounting platform is a teak cutting board. As Sherlock Holmes would say to Dr. Watson, "It is simplicity itself!" Well done, Mr. Klemes!. Messrs. Marconi and Bell would be proud! * Circuit design is Marek's variation of a regenerative receiver presented by James Tobola (KC5LDO), who in turn modified it from an article in the September 1995 issue of CQ magazine (p. 48), "Red Hot Radio Returns." That article's author credits the original design to an article appearing in Boys' Life magazine and in the ARRL's "How to Become a Radio Amateur" booklet during the early-to-mid 1950s (it used a 3S4 tube). That's quite a provenance.
Posted March 23, 2017 |
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