C)
If
a
RF
voltage
of
20 mV/P-P
or
more at the
base
and 300 m V
/P-P
or
more at the collector
of
the 7.8 MHz AMP (TR7), the 7.8 MHz
AM P
is
all right.
If
no R F voltage
is
present at the
base,
check
D7
and
D35 circuits.
D)
If
a
RF
voltage
of
34 MHz, 2 V
/P-P
or more
is
readable at the
first
gate
of
the mixer
(FET7) no problem should
be
expected
with
Local Oscillator.
E)
Check
DC
and
RF
voltages
of
each
of
the
following circuits: TR43, TR44, TR45, FET6
and 'FET7 (in this order).
F)
If
voltages do
not
appear at the collector
of
TR43
or
TR44, check the regulators
(TR25
or
TR26).
If
the regulator
has
a
DC
output
of
approx. 5
to
7 V. the regulator should
be
all
right.
NO TRANSMISSION (SSB)
A)
If
AM
transmit
and
modulation
are
working
properly, the problem
is
in the
circuit
of
7.8
MHz AMP (TR6) or in the
circuit
of
Balanced
Modulator (IC2)
or
in the Microphone AMP
(TR 16). .
If
no
RF
voltage
of
7.8 MHz, 50
mV
/P-P
appears at pin 8
of
IC2, check circuits
from
TR28
to
pin 8
of
IC2.
If
no audio signal
of
approx. 70
mV/rms
appears at pin 1
of
IC2 under modulation,
check circuits before TR 16.
B)
If
the voltage reading at pin 8
and
pin 1
of
IC2
are
correct then problems
are
with
TR6
bias
circuit
or
D6.
C)
If
the
output
of
TR6
is
produced properly
check item
D)
and
E)
of
NO
TRANSMIT
(AM) above.
NO
AM
MODULATION
The signal in the modulation
circuit
flows
through IC3 - D22 -
D21
-
TR20
-
TR22
- IC4.
Therefore check
to
determine at what
stage
this
signal
ceases
(to
isolate a defective part).
If
no
signal appears at pin 2
of
IC3,
it
is
probable
that
there
is
a short
circuit
between the collector
and
emitter
of
the clamping transistor (TR 18) or
between the collector
and
emitter
of
the TR 19.
NO NOISE BLANKER OPERATES
A)
If
the
RF
output
voltage
of
TP-5
is
100
mV
or
less
with
Noise Blanker ON, when signal
of
23.5 MHz 200
J1V
carrier
is
applied
to
antenna, check the
RF
AMP circuits (lC1)
and
L 1
and
L2.
B)
If
a pulse noise
is
amplified
to
0.7 V/P-P
or
more at the
base
of
TR3
when
an
ignition
noise (or pulse noise)
of
100 mV/P-P
or
more
is
applied
to
the antenna, the circuits
of
TR 1
and
TR2
should
be
all right. And
if
a pulse
noise
of
approx. 0.2 V /P-P
is
produced at the
collector
of
TR3,
it
also
is
all right.
NO LED CHANNEL INDICATOR LIGHTS
A) I n the event a specific channel fails
to
light,
it
is
probable
that
there
is
an
open
circuit
in the
LED display
or
bad
contact in the channel
selector switch.
B)
If
all channels fail
to
light, the regulator
(TR36
& TR37)
circuit
is
defective.
-18-
To Next Page
Loading...
