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The bottom scan shows the top
of the CD case, with the CK722 radio insert installed inside the case –
this shows the condition before the holes are drilled in the case and the
screw/knurled nut combinations are installed and the components of the
radio are added. The top scan is a
close-up of the method used to attach the CK722 into the circuit. The knurled nuts are hand tightened, and
this method is used for both the CK722 transistor and the CK705 diode
required for the radio. The three
different case types of the CK722 are shown in the middle photo. The silver case is the most common and
was used in the late 50s through to the mid 1960s – this is the best
performing CK722 type, most likely because transistor technology had
improved considerably by this time. In my opinion, the blue-cased CK722 is
the most interesting visually. This
type also performs well. The black
epoxy case was used only on the earliest CK722s, from 1953 through
1955/56. Many of these CK722s are
no longer functional, probably because the epoxy case was not hermetically
sealed, and moisture penetration has degraded the transistor junctions over
time.
50th
Anniversary CK722 Radio
Go To Page 5
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