50th Anniversary CK722 Radio




Above photo shows the completed radio.  Performance is surprisingly good, considering the simple circuit.  With a short wire attached to the antenna clip and then to a metallic object such as a window frame (or maybe a metal bed frame), I was able to receive several local stations clearly and with good volume. No ground connection is required, although this would probably add volume.  Since both the tuning capacitor and the loopstick coil are variable, I could use a combination of both knobs to perform “fine tuning” quite easily and avoid any station overlap.  Battery drain is very low, and no power switch is required – the battery power is “ON” only when the earphone is connected to the circuit.   


The following is an excerpt from the book, “The Story of the CK722”, and seems an appropriate way to conclude this project:


Many of the talented and dedicated professionals and amateurs who have been responsible for the tremendous rise of the electronics industry over the past four decades can still remember the time when, as a young hobbyist, they were able to scrape together enough money (maybe through saving allowance or cutting the neighbor’s grass) to buy that first CK722 – can you still recall the smell of the solder and the absolute delight of hearing a local radio station coming through “loud and clear” on that newly constructed transistor radio powered by, of course, a gleaming, bright blue CK722?


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