Instruction manual

HR-80• 11
positive lead into the ‘+’ marked hole on the PC board.
 10) Install C11, a 100-220µF electrolytic capacitor. Remember to
observe correct polarity. C10 and C11 provide voltage stabilizing
which directly improves the performance of the NE602 oscillator.
 11) Install C2, 150pF ceramic disc capacitor (marked 150 or 151).
This capacitor is a first step in setting up the resonant frequency
of the NE602’s internal oscillator, using the resonant LC circuit to
be created along with C1, C3 and L1.
 12) Install C1, 150pF disc capacitor (marked 150 or 151).
 13) Install C3, .01µF disc capacitor (marked 103 or .01 or 10nF).
 14) Install L2, shielded oscillator coil (marked 5015).
 15) Install C4, .01µF disc capacitor (marked 103 or .01 or 10nF).
C4 adds variable capacitance of the varactor tuning network to
the oscillator circuit already formed by L2, C1, C2 and the NE602.
 16) Install D1 & D3, the 1N4002 diodes, making sure that the
cathode or banded end is oriented towards the back of the PC
board. This diode performs the function of a varactor diode. A
varactor diode acts like a variable capacitor whose capacitance is
controlled by the voltage across it. There is nothing fancy about
the varactor diodes, so we are using a common rectifier diode as
a varactor.
 17) Install R5, 10k ohms (brown-black-orange)
 18) Install R2, 10k potentiometer tuning control.
 19) Install R3, 10k potentiometer volume control. This control
varies the level of audio from pin 4 of the NE602 to the LM386
audio amplifier.
 20) Using a scrap piece of wire, snipped from an installed
component, install JMP-1. Jumpers are required sometimes in PC
board layout to make a connection that has to cross over other
PC-board traces.This particular jumper brings 9 volts from the
power switch to the long circuit trace supplying voltage to the
entire circuit. Notice how the jumper crosses over the other traces
leading from the volume control.
 21) Install S1, the power switch.