System Check - Elenco Electronics AM/FM-108TK Manual

ffiUREMENTS
AM DETECTOR AND AGC
TEST
Connect
yourVOM and
RF generator as shown in Figure 14'
TP1 5
Figure 14
Set the VOM
to accurately read
2 volts DC and set the
""tprt
of the RF generator for
455kfz'
no
.T*li:":
anO
minimum voltage
output' Turn
the power ON and
rio*fy
increase the amplitude of the generator
until the
SYSTEM CHECK
Connect your equipment as shown in Figure
15'
voltage at TP5 just starts to
droP'
the AGC threshold with no lF gain'
amplitude
setting
on the
RF
lf your
RF
generatfA;es not
have amFlitude modulation and
-'
'
you
O-o
not
have an
oscilloscope' skip to Section 3'
This point is ca
Make a note of
generator
ht
Oscilloscc
TP1 5
lf
this test failt
and
TPS.
Tu
.001pF
TP15
Figure 15
Set
the RF
generator
at
455kHz '
lk1z at
B0%
modulationandminimumvoltageoutput.Turnthepower
ON anO
set the volume contiol
at maximum'
Slowly
aOlust
the amplitude
of
the
RF
generator output
until you
hear the l
kHz
tone on the sPeaker'
the power OFF and check R42,
D4
power
OFF.
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