Heathkit model IG-4244
Oscilloscope Calibrator
Date Calibrated: _____/_____/_____
Calibration Procedure
• Turn on the oscilloscope and allow it to warm up and stabilize.
• Disconnect all external components from the front panel terminals.
✔ If the instrument is not operating properly, see INITIAL TESTS section. [Construction Manual, pages 49 – 50]
Ancillary Equipment Needed
Digital Voltmeter (DVM)
25-MHz Oscilloscope
Coax cable [RG58]
Coax cable [RG58] with a 50W load
* * * * * * *
INITIAL SETUP
Refer to Pictorial 2-8 Insert
Illustration Booklet, page 7
( ) Set the POWER switch (SW2) to the OFF position.
( ) Adjust the TIME LEVEL control (R2) to the center of rotation.
( ) Set the TIME—SINE—VOLTS switch (SW1) to the VOLTS position.
( ) Install the 2-hole shorting jumper over the two plug block pins (P101) at the DC position [circuit board].
( ) Set the 20 V control (R178) [circuit board] to the center of rotation.
( ) Set the 100 V control (R179) [circuit board] to the center of rotation.
( ) Set the 50 V control (R181) [circuit board] to the center of rotation.
( ) Connect the DVM negative test lead to the outer barrel of the SINE—VOLTS output BNC.
( ) Insert a short length of solid wire or solder into the center conductor of the same BNC.
( ) Connect the DVM positive test lead to the same piece of solid wire or solder.
( ) Make sure that the heat sink on IC (U118) [circuit board] does not touch the case of transistor (Q113) [Pictorial 2-6, page 6 of the Illustration Booklet]
♦ WARNING: Line voltage is present at several places circuit board.
[Pictorial 2-9, page 52 of Construction Manual]
( ) Set the POWER switch (SW2) to the ON position.
♦ WARNING: DO NOT touch the shielded cable center conductor when the RANGE switch (SW101) is in the VOLTS position.
( ) Set the RANGE switch (SW101) to the 20 volts position.
( ) Adjust the 20 V control (R178) [circuit board] until the meter indicated exactly 20.00 volts.
( ) Set the RANGE switch (SW101) to the 50 volts position.
( ) Adjust the 50 V control (R181) [circuit board] until the meter indicated exactly 50.00 volts.
( ) Set the RANGE switch (SW101) to the 100 volts position.
( ) Adjust the 100 V control (R179) [circuit board] until the meter indicated exactly 100.0 volts.
( ) Set the RANGE switch (SW101) to the 20 volts position.
( ) Disconnect the DVM test lead from the SINE—VOLTS output BNC.
( ) Remove the wire or piece of solder from the center conductor of the BNC.
* * * * * * *
OSCILLOSCOPE INITIAL SETUP
( ) Set the vertical input attenuator switch to the 5 V/DIV position.
( ) Set the Trigger source switch to INT.
( ) Set the Trigger type switch to AC.
( ) Set the Trigger polarity switch to + (positive).
( ) Set the Trigger mode switch to AUTO.
( ) Set the Vertical Input attenuator switch to the 0.2 V/cm position.
( ) Set the Horizontal Sweep Rate switch to the .2 msec/cm position.
* * * * * * *
TIMING PULSES
Refer to Pictorial 2-10
Construction Manual, page 53
( ) Set the TIME—SINE—VOLTS switch (SW1) to the TIME position.
( ) Set the RANGE switch (SW101) to the 200 nsec position.
( ) Connect the coax cable with the 50W load to the TIME output BNC.
( ) Connect the same coax cable from the Oscilloscope Calibrator to the vertical input of the oscilloscope.
* * * * * * *
Refer to Pictorial 2-11
Construction Manual, page 54
( ) Adjust the Oscilloscope Trigger Stability control to obtain a waveform similar to Pictorial 2-11. [Construction Manual, page 54]
• Due to the frequency limitations of many oscilloscopes, the faster rise time waveforms may not be observable.
( ) Set the RANGE switch (SW101) to each frequency position below, and observe the waveform.
♦ Readjust the oscilloscope’s horizontal sweep rate as necessary.
( ) 1 s ( ) 500 ms ( ) 200 ms ( ) 100 ms ( ) 50 ms ( ) 20 ms
( ) 10 ms ( ) 5 ms ( ) 2 ms ( ) 1 ms ( ) 500 ms ( ) 200 ms
( ) 100 ms ( ) 50 ms ( ) 20 ms ( ) 10 ms ( ) 5 ms ( ) 2 ms
( ) 1 ms ( ) 500 ns ( ) 200 ns ( ) 100 ns ( ) 50 ns ( ) 20 ns
( ) Disconnect the coax cable with the 50W load from both the oscilloscope and the Oscilloscope Calibrator.
* * * * * * *
1-V P-P SINE WAVE
Refer to Pictorial 2-6 Insert
Illustration Booklet, page 6
( ) Set the Oscilloscope Vertical Input attenuator switch to the 0.2 V/cm position.
( ) Set the Oscilloscope Horizontal Sweep Rate switch to the .2 msec/cm position.
( ) Set the TIME—SINE—VOLTS switch (SW1) to the SINE position.
( ) Connect the coax cable without a load to the SINE—VOLTS output BNC.
( ) Connect the same coax cable from the Oscilloscope Calibrator to the vertical input of the oscilloscope.
( ) Adjust control (R192) [bottom side of circuit board] counter-clockwise for the cleanest 1V P-P sine waveform similar to Pictorial 2-12. [Construction Manual, page 55]
♦ Adjust the oscilloscope’s vertical attenuator as necessary.
( ) Set the Oscilloscope Calibrator’s POWER switch (SW2) to the OFF position.
( ) Remove the 2-hole shorting jumper from the plug block pins (P101) [circuit board].
* * * * * * *
VOLTAGE
Refer to Pictorial 2-13 Insert
Construction Manual, page 56
( ) Set the Oscilloscope Vertical Input attenuator switch to the 0.2 V/cm position.
( ) Set the Oscilloscope Horizontal Sweep Rate switch to the 1 msec/cm position.
( ) Insert the 2-hole shorting jumper over the two plug block pins (P101) at the NORMAL position [circuit board].
( ) Set the TIME—SINE—VOLTS switch (SW1) to the VOLTS position.
( ) Set the RANGE switch (SW101) to the 1 volt position.
( ) Set the POWER switch (SW2) to the ON position.
( ) Adjust the Oscilloscope Trigger Stability control to obtain a waveform similar to Pictorial 2-11. [Construction Manual, page 54]
( ) Set the RANGE switch (SW101) to each voltage position below, and observe the waveform.
♦ Adjust the oscilloscope’s vertical attenuator accordingly.
( ) 1 mV ( ) 2mV ( ) 5 mV ( ) 10 mV ( ) 20 mV ( ) 50 mV
( ) 100 mV ( ) 200 mV ( ) 500 mV ( ) 1 V ( ) 2 V ( ) 5 V
( ) 10 V ( ) 20 V ( ) 50 V ( ) 100 V
( ) Set the RANGE switch (SW101) to the 1 mV position.
( ) Set the Oscilloscope Calibrator’s POWER switch (SW2) to the OFF position.
( ) Disconnect the coax cable from both the oscilloscope and the Oscilloscope Calibrator.
( ) Disconnect the line chord from the line voltage outlet.
( ) Calibration is complete.