Note
Osterman, fourth edition, p. 107.
The R-390A shared design similarities with its predecessor, the R-390. The 26-tube set offered a selection of crystal and mechanical filters in its 455 kHz IF. It was introduced in 1954 as a lower cost alternative to the R-390 and remained in production for 30 years. A dozen other companies joined Collins in manufacturing the R-390A under contract. (32)
