Note
RCA introduced the AR-88 in 1941, on the eve of World War II. The 14-tube receiver continued to be produced throughout the war with much of the production going to England and other allies. It covered .54-32 MHz and had a crystal filter but no phasing control. A low-frequency model, the AR-88LF, was also made.
References
A brief article on the history of the AR-88. QST, Apr 1977, p. 91.