Heathkit IB-5281 - Page 34

Page 32
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DIAL CALIBRATION
Refer to Pictorial 4-4 for the following steps.
Preset the front panel controls as follows:
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BALANCE control R26 fully counterclockwise.
RANGE switch to RX1.
LEVEL control fully counterclockwise.
Plug both alligator clips into the Z, terminals.
Locate the 100 0 (brown-black-brown) resistor
which was left over, and install it between the
two alligator clips as shown.
Place the POWER switch to ON. The meter
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0.
Gradually increase the LEVEL control until the
meter reads 10.
SO
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350) RX10K
Rx100
HEATHEIT ALC BRIDGE
RANGE
LX 1mH
Lx OH
CM 1pF
VN
GS
Rx1
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MODEL 18-5281
CX 0001 uF
Cx O1UF
Increase the LEVEL control fully clockwise,
rock the BALANCE control back and forth a few
_ times to obtain the best null possible.
Very carefully, loosen the setscrew on the ba-
lance control knob without moving the control.
Position the dial pointer so it is over the 100
mark on the A scale. Tighten the setscrew.
Check the null on the meter and make sure the
pointer is directly over the “100” mark. If it is
not, repeat the previous step.
Turn the LEVEL control
terclockwise.
fully coun-
Return the POWER switch to OFF.
Disconnect the 100 2 resistor and remove the
alligator clips from the front panel terminals.
Note: Save the resistor in case you would like to
recalibrate your unit later.
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Supply, disconnect it from
This completes the ‘Dial Calibration.” Proceed to
“Final Assembly.”