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tested
on frequency, this should amount
to no
more than
a
check
on the tuning.
The 813 stage is
provided with
a
convenient grid
current meter, and the oscillator tuned for maximum grid current,
which should
be
8 -
10
milliamperes with
no
voltage
on the
plate
of the tube.
Before applying the high voltage,
set the
modulation monitor
pick -up coil L12, for minimum coupling,
at
right angles and
as
far removed from the tank coil
as
possible
so
as
not
to
overload
the
modulation monitor
input.
Set the two
modulator bias rheo-
stats R4 and R5
to
maximum bias voltage, that
is,
fully counter-
clockwise.
Set the
neutralizing condenser
C28
at
half capacity.
Remove the plate connector from one
of the
8008 rectifier tubes,
making
sure the
connector
is
not grounded.
Disconnect
the
primary
of the
plate transformer
Tl,
terminals
1
and
2
or
3
whichever
is
used.
When
the
filaments have been on
30
seconds, the time
delay relay
E6 closes and the "FILAMENT"
light will light.
With the back door closed, pressing the high
voltage
"ON"
switch
S2
should cause the plate contactor E4
to
close.
Pressing the high voltage
"OFF"
switch should cause this
contactor
to open.
With the contactor closed in the high voltage
ON condition, opening the
back door should cause the contactor
to open.
Opening the door and blocking
or
holding
the door interlock switch
S4,
the high voltage control can then be closed.
With
a
wooden
dowel
or
insulating
stick,
push the armatures
of
the overload
relays
El and then E2.
In each case the
auxiliary relay E3 should
operate and cause the plate contactor
to open.
CAUTION:
The
armatures
of
these relays
are in the 220
volt circuit and should
NEVER
be touched with the body.
If the
control circuit does not operate
as
described, some fault
exists and should be remedied before continuing.
With the high
voltage transformer disconnected,
no
damage
to
equipment should
be incurred while testing the control circuits.
With the control circuits functioning properly,
the
high voltage
transformer may be reconnected,
and the ridio
frequency circuits
adjusted.
9/11/63
-9-
BC- 250GY
-1
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