Note
QST, Dec 1939, p. 1.
Radio News, Jan 1940, back cover.
QST, Oct 1941, p. 2. (ad with tube lineup)
Radio Craft, Dec 1944, p. 132.
A refinement of the S-20.
The 1939 version of the Sky Champion added an additional IF stage, a noise limiter, and electrical band spread, and used nine tubes (instead of eight). Optional external S-meter (SM-20).
References
Brief review. Radio, Jan 1939, p. 29.
Review: Radio, Feb 1940
Coverage: 540 kHz to 44 MHz
IF: 455 kHz
Built-in speaker
BFO
ANL
Bandspread
Power: 120 VAC
Tubes: (1) 80, (1) 6F6, (1) 6J5, (1) 6H6, (1) 6SQ7, (3) 6SK7, (1) 6K8