Radio’s Master, 13th edition (1948), p. J-74
Lafayette catalog number 89, p 131.
QST, Apr 1953, p. 117. (CPO-128)
QST, Apr 1954, p. 103. (CPO-128A)
QST, Jan 1968, p. 160. (CPO-128B) (probably way before this)
Walter Ashe catalog, 1954, p. 13. (CPO-130)
CPO-130 is the same as CPO-128 but designed for use with earphones.
The toggle switch on the side is labeled “M” (monitor) and “C” (code). The cord coming out of a grommet near the switch is an RF pickup loop.
