Assertion: tube receiver | /r/HasProperty | refined into cheap-to-manufacture form
Facets:
value: during the 1940s
type: TEMPORAL
Source sentences:
text: During the 1940s the vacuum tube superheterodyne receiver was refined into a cheap-to-manufacture form called the " All American Five " because it only required 5 tubes, which was used in almost all broadcast radios until the end of the tube era in the 1970s.