Object Details
maker
Sonatron Tube Company
Description (Brief)
A resistance-coupled audio amplifier designed to replace transformer coupled stages in a broadcast receiver, or to operate as a straight audio amplifier following a standard detector. The manufacturer supplied a type MJ-X6 (red) tube, a type MJ-X30 (silver) tube, and a type MJ-X20 (blue) tube. Tube designation denotes amplification factor. Includes original package and instruction booklet.
Transformer coupling in audio amplifiers was introduced by De Forest as early as 1912. The simplicity in design of such units led to their popularity during the 1920s. However factors such as bulkiness and poor frequency response eventually led to resistance coupled units. With the advent of high gain tetrode and pentode tube types, transformer coupling became generally obsolete with the exception of impedance matching transformers in the audio output stage of receivers.
Location
Currently not on view
Credit Line
from Franklin Wingard
date made
1924
ID Number
EM.321490
catalog number
321490
accession number
241556
Object Name
Amplifier
amplifier kit
radio amplifier
audio amplifier
Other Terms
Amplifier; Radio
Measurements
box: 2 1/2 in x 9 7/8 in x 8 5/8 in; 6.35 cm x 25.0825 cm x 21.9075 cm
See more items in
Work and Industry: Electricity
Data Source
National Museum of American History
Link to Original Record
Record ID
nmah_709746