Heathkit IG-1275 Manual page 72

Page 72
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CALIBRATION
If you are initially calibrating this instrument, preset
all of the internal controls to the center of their rota-
tion. If you are recalibrating the instrument, do not
preset the internal controls.
wt If necessary, remove the top, bottom, and side
panels.
"} Refer to Figure 1 (on Page 15 in the Illustration
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ed
Booklet) and preset the front panel controls as
follows:
FREQUENCY control — 3.0.
FREQUENCY switch — 10%.
FUNCTION switch — CW.
TRIG LEVEL control — AUTO TRIG (detent).
MODE switch — Square wave.
SYMMETRY switch — OUT.
% POSITIVE control — Center of rotation.
SWEEP switch — 100 mS.
ATTENUATOR switch — 0 dB.
ATTENUATOR VARIABLE control — POWER
OFF (detent).
nally between 110 and 135 volts, set the
NOR/LOW switch (on the switch mounting
( )
WARNING: High AC voltage is present on the chas-
sis at several locations when the line cord plug is
connected to AC power. Refer to Figure 2 (in the
Illustration Booklet).
NOTE: During calibration, you will be using three
different circuit board figures. Pay close attention to
the figure references in this section.
Connect the line cord plug to an AC power
receptacle.
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Refer to Figure 3 (on Page 15 in the Illustration Book-
let) for the following steps.
(- } Connect the DC voltmeter between TP6 (test
point 6) and ground. NOTE: Use the black wire
on the front panel Frequency/Sweep controls
for ground.
NOTE: Refer to Test Chart #2 in the Illustration Book-
let if you have difficulty in the following steps.
WS) Turn the Generator on (rotate the AT-
TENUATOR VARIABLE control fully
clockwise to CAL.) The PWR lamp should il-
luminate and the DC voltmeter should indicate
approximately —15 +2 volts.
Allow approximately 30 minutes for the
Generator components to warm up and
stabilize.
Adjust VOLT ADJ control R108 for —15 +0.5
volts. Record this voltage reading _*2°¢
t 4.47
Now connect the DC voltmeter to TPS and ad-
just BAL control R107 for a positive voltage
equal in value to the voltage in the previous
step.
Remeasure the —15 volt and +15 volt supplies
(TP6 and TP5). Although the negative supply
can vary +0.5 volts, the positive supply must be
identical in value to the negative supply.
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