50^th Anniversary CK722 Radio BUILD YOUR OWN WORKING HISTORIC CK722 RADIO
PROJECT DETAILS (Continued) The two above scans are shown to illustrate other CK722 circuits from the 1950s. The top scan is from the famous 1957 booklet: “ Volume II Raytheon Transistor Applications”. This circuit is very similar to the Valandy radio circuit used for our 50th Anniversary CK722 radio. The bottom scan is the circuit used for the first ever published CK722 radio project (in the Feb 1953 Radio and Television News magazine).	PROJECT DETAILS (Continued) The schematic shown above represents the circuit that has been used in the 50^th Anniversary Radio. This circuit is basically the same as that used in the Valandy radio kit, shown on the previous page, and is similar to many CK722 projects from the 1950s and 1960s. The CK722 is used as an audio amplifier and works best with a high impedance earphone (2K ohm). Station selection is accomplished by the parallel combination of the 365mmfd variable capacitor and the variable inductor “loopstick”. The CK705 germanium diode provides detection of the radio signal and the audio component is coupled by the .02mfd capacitor to the base lead of the CK722, which amplifies the signal in a common emitter circuit and directly drives the earphone. 50th Anniversary CK722 Radio Go To Page 4
50 YEARS of the CK722 A New Volume of Projects Featuring the Most Famous Transistor Ever Made COPYRIGHT © 2003 by Jack Ward. All Rights Reserved. http://www.ck722.com