27 R-442 RECEIVER ALARM CLEAR AND KY-57 KEYING CIRCUIT. To clear the KY-57
alarm or to load the KY-57, a keying circuit has been provided (Figure 98).
This is accomplished by applying a ground to the KY-57 keying circuit. At
the J-3514/U, when the substation ALARM CLEAR button is pressed, a ground is
applied through J2 pin C, through the CX-13062/U to the KY-57 AUDIO jack pin
C, to the ALARM CLEAR and keying circuit.
(Trace this circuit on your
R-442 alarm clear and Fill keying circuit.