The speaker in the TR-1 was a 2.75” Jensen - larger than most of the ‘60s pocket radios - so it might sound okay. ![]() The 1954 TR-1 had only four transistors with a single audio stage driving the speaker, while the later six-transistor units invariably had an audio amp stage following the volume control and feeding push-pull outputs through a driver transformer. Starting around 1960, the market was flooded with six-transistor pocket radios - with many of those made for American companies. The question really was never answered because the actual production serial number on the commemorative TR-1 they found was not revealed.Īfter having the radio featured on the program, I started to wonder what it actually sounded like 62 years ago. The question for the ‘detectives’ was whether this was the oldest transistor radio in existence. The radio I’m restoring in this article ( Figure 2) was featured on an episode of the PBS series “History Detectives.” There are a number of good websites to learn the history of the TR-1, and one of the most complete is The site is run by Don Pies, the son of Regency co-founder John Pies. Early advertisement for the TR-1.ĭespite its high price, Regency sold the first run of about 100,400 TR-1s before introducing the TR-1G (which was re-designed with a PNP output transistor) in 1956. An early advertisement is shown in Figure 1.įIGURE 1. Options included a leather case for $3.95 and an earphone for $7.50. Of course, the battery was “not included.” The TR-1 pocket radio was introduced just before Christmas 1954 and sold for $49.95. (Industrial Development Engineering Associates) of Indiana to produce the first transistor radio under their Regency brand. The main benefits of the devices were their small size and low power requirements, so they decided a transistor pocket radio would be a good product to introduce the technology to the public. Looks like an OVRA auction item.When Texas Instruments developed a process to mass produce transistors in the early 1950s, they wanted to show the advantages over tubes to spur marketing. Now what.? I really don't need a 1967 transistor table radio taking up space. speculation, no schematic! So, I rewired the new B+ filter to include an RF chokes in both the ground line and B+ line. There seems to be one or two tiny RF caps from the PT to the FM RF/converter stage. I had inadvertently by-passed these spirals on the PCB. ![]() it looks like they are used to isolate the Power line from ground and B+ at 100 MHz RF so that the power cord could be a decent "long wire" FM antenna, not grounded at RF. Then I realized that the spiral coils on the PCB were RF chokes. ![]() By touching various points on the PCB with a 3 ft wire the FM came on strong! This radio uses the line cord as an FM antenna. but I forgot to note some PCB connections! Neither did I take a photo! Mea culpa! I put it all back based on intuition and first principles, and it worked. In so doing I unsoldered the PT and cap wires from the PCB to make the new "air circuit". I did a "Q&D" B+ volts drop calculation - still OK since we have 125 VAC mains and the radio was designed for 117 VAC. ![]() Decided to put in a pi-section B+ filter with two caps, 1000 MFD after the diodes and the 2,200 after a 27 ohm series resistor. Replaced it with a tested 2,200 MFD from the spares box, but still some audible hum. there was a quite audible 120 Hz hum! The PT is a 6 - 0 - 6 VAC with two diodes to a 1000 MFD capacitor - took it out and tested it. I re-strung it and it worked, of course.īut, new problem. even though it is a cheap radio, I could not just toss it in the trash. I have to confess to being an "obsessive compulsive fixer" of junk. she simply bought a new "Tivoli" radio from Bay Bloor Radio in Toronto (no comment!) I was given the radio by a "civilian" friend who said the dial was stuck at one end. here's the abbreviated story, not reflecting all that well on me! I think I've fixed it without a schematic.
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