page_title: Tube tester
section_title: Self-service tube testers
hierarchical_section_title: Tube tester / Self-service tube testers
caption_attribution_description: English: A photo of an RCA self-service tube tester on display at the Oklahoma History Center in Oklahoma City, Oklahoma, USA.
context_page_description: A tube tester is an electronic instrument designed to test certain characteristics of vacuum tubes. Tube testers evolved along with the vacuum tube to satisfy the demands of the time, and their evolution ended with the tube era. The first tube testers were simple units designed for specific tubes to be used in the battlefields of World War I by radio operators, so they could easily test the tubes of their communication equipment.
context_section_description: From the late 1920s until the early 1970s, many department stores, drug stores and grocery stores in the U.S. had a self-service tube-vending display. It typically consisted of a tube-tester atop a locked cabinet of tubes, with a flip chart of instructions. One would remove the tubes from a malfunctioning device, such as a radio or television, bring them to the store, and test them all, looking up the instructions from the model number on the tube and the flip chart. If a tube was defective, store personnel would sell a replacement from the cabinet.
  At that time, tubes in consumer devices were installed in sockets and were easily replaceable, except for the CRT in televisions. Devices typically had a removable back with a diagram showing where to replace each tube. There were only a few types of tube socket; a radio or television set would have multiple identical sockets, so it was easy to mistakenly exchange tubes with different functions, but similar bases, between two different sockets.  If testing showed all tubes to be working, the next step was a repair shop. As transistorized devices took over the market, the grocery-store tube-tester vanished.
caption: An RCA self-service tube tester on display at the Oklahoma History Center.
exif: {"Image Make": "Panasonic", "Image Model": "DMC-LZ3", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Microsoft Windows Photo Gallery 6.0.6000.16386", "Image DateTime": "2007:03:22 21:35:22", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "2528", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 50, 53, 48, 0, 0, 14, 0, 1, 0, 22, 0, ... ]", "Image Padding": "[]", "EXIF ExposureTime": "1/8", "EXIF FNumber": "14/5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2007:03:22 11:05:56", "EXIF DateTimeDigitized": "2007:03:22 11:05:56", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "3", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "61/10", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1920", "EXIF ExifImageLength": "2560", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "11152", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF FocalLengthIn35mmFilm": "37", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "Low gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF ImageUniqueID": "CBB839525B144EEA91906A3FE29EF72E", "EXIF Padding": "[]", "EXIF OffsetSchema": "4156"}