[Ron Ramirez]

According to Wenaas, the RA and DA were commercially introduced in December 1920 as was the combination RC (RA and DA in one box). [1] But a RA-DA can be seen in photographs of KDKA's first broadcast which was on November 2, 1920. [2]

Wenaas wrote:

According to historian George Clark, the first RC receiver was sold to W.L. Chubb, a Westinghouse employee, for use at a gathering to hear the election returns transmitted on the first KDKA broadcast on November 2, 1920.

[3]

Wenaas also lists an introductory date of July 1921 for the Aeriola Jr., a crystal set, and December 1921 for the Aeriola Sr. [4]

[1] Wenaas, Eric P. Radiola: The Golden Age of RCA, p. 76.
[2] Ibid., pp. 72-73.
[3] Ibid., p. 76.
[4] Ibid.