Note
QST, Mar 1955, p. 86.
Allied Radio catalog 1956 (copyright 1955), p. 201.
QST, Dec 1956, p. 109. (details)
Walter Ashe catalog 1957 (probably issued in 1956), p. 6. (describes options)
Allied Radio catalog 1959 (copyright 1958), p. 378.
Allied Radio catalog 1960 (copyright 1959), p. 395.
The 600L used a single 813 in class AB2 for 500 watts DC input with 2 watts drive. Central Electronics introduced their "no-tune" technology with the 600L. The 160-10 meter band-switching amplifier employed the company's patented broad-band couplers to eliminate the customary tuning and loading controls.