IEEE Spectrum is the flagship publication of the IEEE — the world’s largest professional organization devoted to engineering and applied sciences. Our articles, podcasts, and infographics inform our readers about developments in technology, engineering, and science.
Enjoy more free content and benefits by creating an account
Saving articles to read later requires an IEEE Spectrum account
The Institute content is only available for members
Downloading full PDF issues is exclusive for IEEE Members
Downloading this e-book is exclusive for IEEE Members
Access to
Spectrum
's Digital Edition is exclusive for IEEE Members
Following topics is a feature exclusive for IEEE Members
Adding your response to an article requires an IEEE Spectrum account
Create an account to access more content and features on
IEEE Spectrum
, including the ability to save articles to read later, download Spectrum Collections, and participate in
conversations with readers and editors. For more exclusive content and features, consider
Joining IEEE
.
Join the world’s largest professional organization devoted to engineering and applied sciences and get access to
all of Spectrum’s articles, archives, PDF downloads, and other benefits.
Learn more →
Join the world’s largest professional organization devoted to engineering and applied sciences and get access to this e-book plus all of IEEE Spectrum’s articles, archives, PDF downloads, and other benefits.
Learn more →
Create an account and get exclusive content and features: Save articles, download collections, and
talk to tech insiders — all free! For full access and benefits,
join IEEE as a paying member.
RADIO REPAIR: Where there are radios, there are radio tubes, and where there are tubes, there are devices for testing them. The Supreme 400B Radio Diagnometer, made by the Supreme Instruments Corp., of Greenwood, Miss., is a particularly fine example of the sort of radio analyzer used by early radio repairmen. It measured AC volts, DC volts, milliamps, and capacitance.