Elenco AM/FM Radio Kit - Manual (Page 53)

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Figure 48
C7 - .001 μ F Discap (102)
R4 - 33k Ω Resistor
(orange-orange-orange-gold)
Q2 - 2N3904 Transistor
(see Figure R)
R5 - 33k
Ω
Resistor
(orange-orange-orange-gold)
R6 - 2.2k Ω Resistor
(red-red-red-gold)
C8 - .005 μ F Discap (502)
L3 - FM Oscillator Coil
(5 Turns)
C9 - 15pF Discap (15)
C10 - 30pF Discap (30)
C11 - 220pF Discap (221)
BANDWIDTH TEST
Connect your test equipment to the circuit as
shown in Figure 48. Set your generator at 10.7MHz
no modulation and minimum voltage output. Set the
scope for 10mV per division. Turn the power ON
and slowly increase the amplitude of the generator
until 40mVpp are seen on the scope. Increase the
frequency until the voltage drops 0.707 of its
original value, 2.8 divisions or 28mVpp. Record the
frequency of the generator until the voltage drops
0.707 of its original value, 2.8 divisions or 28mVpp.
Record the frequency of the low 3dB drop-off point
here:
Fl = _________MHz.
Turn the power OFF. The bandwidth can be
calculated as follows:
Bandwidth = Fh - Fl
Your calculated answer should be between 300 -
500kHz.
Record your calculation:
Bandwidth = _________kHz.
FM OSCILLATOR ASSEMBLY INSTRUCTIONS
GND
TP15
Oscilloscope
GND
TP15
Generator
.001 μ F