Most isolation transformers are 1:1, although tapped models with provisions for slightly adjusting the line voltage (i.e., 120:115-120-125) and continuously variable models do exist. You could receive a fatal shock by accidentally contacting a cold water pipe or damp concrete floor, or destroy any grounded test equipment you connect to the device under test.Īn isolation transformer will interrupt the current path to earth ground and provide safety in these circumstances - both for yourself and your equipment. This can result in a significant safety hazard as now the radio's metal components may become "hot" relative to ground. Unlike transformer-operated radios which are inherently isolated, many more economical radios saved the cost of the transformer and connected the radio's circuitry directly across the AC line. Point the needle to the station on the dial and off you go. Stacks of batteries disappeared and radios went from being pieces of lab equipment with many controls to adjust independently to the format we've retained today. Radio's listening audience grew rapidly in the early days (Radio Retailing, March 1928 via "Radio Manufacturers of the 1920s" by Alan Douglas). It wasn't until widespread electrification of the United States and the development of tubes which could be heated with AC power instead of DC at the very tail end of the 1920s that radio exploded and achieved mass-market status. This ushered in the radio age, but it wasn't until about 20 years later that radio finally left the lab and made it to consumer's homes.Īn early radio with multiple controls the Barawick Five (Popular Mechanics, November 1926).Įven then, most radios still operated on stacks of expensive batteries which had to be replaced often to deliver the high voltages necessary to operate. The first practical vacuum tubes were invented in 1907 by Lee DeForest, who developed the "Audion" - the world's first triode capable of amplification. The flow of these electrons can then be controlled by charges placed on the tube's internal elements. Vacuum tubes operate on the principle of thermionic emission, where certain metals heated to white-hot in a vacuum will give off electrons.
#TRANSISTOR RADIO REPAIR FULL#
In this first article, I'll cover some tips for what to look for on your old radio to judge its condition, and do a full inspection of the internals to see what work will need to be done.
#TRANSISTOR RADIO REPAIR SERIES#
Over a series of articles, I'll be performing a full electrical restoration on a 1937 DeWald Model 618 vintage radio from start to finish: evaluating its condition, performing the restoration work, and aligning and verifying its performance after service is complete. We were still learning the engineering and physics underlying all this new technology.Ĭompeting standards emerged and fell by the wayside, and huge advances were made in the span of only a few years - not to mention some vicious patent wars - which all mean that no two radios are alike.Įven still, since radio was the only means of home entertainment for decades, there's plenty of service information out there to help you through the process, and there's nothing quite like the feeling of hearing a piece of history crackle back to life after a successful repair job. Even though they're ancient by today's standards, these old tube radios can almost always be brought back to life, and there's still plenty of broadcasts out there for them to receive! Not to mention, they just look so classy and have a presence few modern electronics can match.įixing up a vintage radio is a little different from fixing up many other types of gear, since the entire field of electronics had only just been invented when they were first made. Or, perhaps you've inherited your grandparent's precious tube console - now a family heirloom - that stood as the centerpiece of their living room for many years.
Maybe you were digging around in the attic helping your parents downsize, and found their old wooden tube radio from many years ago stashed away. » Skip to the Extras It’s fun - and easy - to bring your vintage radio back to life!
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