Characteristics of Metal Tubes - and Other "Octal" (8-Prong)-Base Types
Radio Service Data Sheet
October 1935 Radio-Craft

October 1935 Radio-Craft

[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

This is a different type of Radio Service Data Sheet in that rather than presenting a schematic and service data on a particular piece of electronic equipment, it provides a table of "The First 10 Metal Tubes" introduced to the industry. As reported in other articles I have posted from the mid-1930s era magazines, the advent of vacuum tubes that used a metal envelope rather than the typical glass envelope was pitched as the most significant advancement in electronics since the invention of the amplifier tube itself (Lee de Forest's Audion) in 1906. In fact, much of this October 1935 edition of Radio-Craft is dedicated to doting over the metal tube.

Characteristics of Metal Tubes - and Other "Octal" (8-Prong) Base Types

R-RCA and Raytheon; K-Ken.-Rad; A-Arcturus; T-Triad; N-National Union; S-Sylvania. These letters appearing after the tube types above mean that data was available from the makers on these particular types. Some manufacturers do not as yet make all the types at present available.

Arcturus tube designations are all terminated by "G," meaning glass-"metal"; the Triad termination is "MG", meaning metal-glass. Where manufacturers differ somewhat in their tube characteristics, the tube is listed twice, as is the case with the 6A8. The power tubes, 6D5 and 6F6 appear more than once because they are used under different operating conditions. The 6H6 is equivalent to the two diodes of a 75, while the 6F5 resembles the triode section of a 75. The Triad 50A2-MG and 50B2-MG are ballast tubes, both having a voltage drop of 50, the former for use with one Type No. 40 pilot lamp and. the latter for use with two. They are to be used in A.C.-D.C. sets.

Posted November 13, 2023
(updated from original post on 7/29/2016)

Radio Service Data Sheets

These schematics, tuning instructions, and other data are reproduced from my collection of vintage radio and electronics magazines. As back in the era, similar schematic and service info was available for purchase from sources such as SAMS Photofacts, but these printings were a no-cost bonus for readers. There are 255 Radio Service Data Sheets as of April 30, 2025.

Exodus Advanced Communications Best in Class RF Amplifier SSPAs - RF Cafe Website

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a lady's voice announced "You've Got Mail" when a new message arrived...