Heathkit Model ID-101

Electronic Switch

Date Calibrated:   _____/_____/_____

Calibration Procedure

✔ Disconnect all external cables, components, and wires from the output terminals.

· All controls and switches are described as labeled on either the instrument or the schematic diagram.

✔ Use an insulated or non-conducting screwdriver when making any rear or side panel internal adjustments.

Ancillary Equipment Needed

Audio Generator

Oscilloscope

VTVM

* * * * * * *

FRONT PANEL INITIAL SETUP

Refer to Figure 1

Construction Manual, page 24

(    )         Set the POWER switch (S1) to the OFF position.

(    )         Set ATTENUATOR A switch (S3) to the GND position.

(    )         Set ATTENUATOR B switch (S4) to the GND position.

(    )         Adjust the A GAIN control (R9) to full counter-clockwise.

(    )         Adjust the B GAIN control (R10) to full counter-clockwise.

(    )         Adjust the SEPARATION control (R7A & R7B) to the center of rotation.

(    )         Set the MODE switch (S2) to the A position.

* * * * * * *

BACK PANEL INITIAL SETUP

Refer to Figure 2

Construction Manual, page 24

(    )         Adjust the A ZERO SET control (R113) to the center of rotation.

(    )         Adjust the B ZERO SET control (R114) to the center of rotation.

(    )         Adjust the A BALANCE control (R105) to full counter-clockwise.

(    )         Adjust the B BALANCE control (R106) to full counter-clockwise.

* * * * * * *

CALIBRATION

(    )         Connect the line cord to the AC power lines.

(    )         Set the POWER switch (S1) to the ON position.

(    )         Set the oscilloscope’s power switch to the ON position.

               (Allow the unit to warm up for 5 minutes.)

(    )         Adjust the oscilloscope’s trace to the center of the display.

(    )         Adjust the oscilloscope’s vertical gain for a 2.5 V signal.

(    )         Connect a pair of test leads or a coax cable to the oscilloscope’s vertical input.

(    )         Connect the same pair of test leads or coax cable to the Electronic Switch’s OUTPUT.

* * * * * * *

ZERO SET AND BALANCE ADJUSTMENTS

Ø Use either the AC-coupled or DC-coupled procedure below depending upon type of oscilloscope used.

** DC-Coupled Oscilloscope Adjustments **

(    )         Set the MODE switch (S2) to the A position.

(    )         Adjust the A GAIN control (R9) to full clockwise.

(    )         Adjust the A ZERO SET control (R113) to position the trace at 2.5 volts on a calibrated oscilloscope.

(    )         Adjust the A BALANCE control (R105) clockwise to center the trace to approximately zero.

(    )  (    )₁         Adjust the A GAIN control (R9) from full clockwise to full counter-clockwise.

(    )  (    )₂         Adjust the A BALANCE control (R105) until the trace remains stationary.

· Repeat the above 2 steps * until no change is observed when rotating the A GAIN control (R9).

(    )         Adjust the A GAIN control (R9) to full clockwise.

(    )         Adjust the A ZERO SET control (R113) to center the trace.

(    )         Repeat the above 2 marked steps * until no change is observed when rotating the A GAIN control (R9).

* * * * * * *

(    )         Set the MODE switch (S2) to the B position.

(    )         Adjust the B GAIN control (R10) to full clockwise.

(    )         Adjust the B ZERO SET control (R114) to position the trace at 2.5 volts on a calibrated oscilloscope.

(    )         Adjust the B BALANCE control (R106) clockwise to center the trace to approximately zero.

(    )  (    )₁         Adjust the B GAIN control (R10) from full clockwise to full counter-clockwise.

(    )  (    )₂         Adjust the B BALANCE control (R106) until the trace remains stationary.

· Repeat the above 2 steps * until no change is observed when rotating the A GAIN control (R9).

(    )         Adjust the B GAIN control (R10) to full clockwise.

(    )         Adjust the B ZERO SET control (R114) to center the trace.

(    )         Repeat the above 2 marked steps * until no change is observed when rotating the B GAIN control (R10).

(    )         Skip down to the ATTENUATOR ADJUSTMENTS section.

** AC-Coupled Oscilloscope Adjustments **

♦ Requires the use of a VTVM.

(    )         Set the VTVM’s range switch to the 5-volts position.

(    )         Set the VTVM’s input switch to the –DC position.

(    )         Adjust the VTVM’s Zero Adjust control to center the meter pointer.

(    )         Connect the VTVM’s ground lead to one of the Electronic Switch’s GND posts.

(    )         Connect the VTVM’s probe to the Electronic Switch’s OUTPUT terminal.

(    )         Set the MODE switch (S2) to the A position.

(    )         Adjust the A ZERO SET control (R113) to indicate 2.5 volts on the VTVM.

(    )         Adjust the A GAIN control (R9) to full clockwise.

(    )         Adjust the A BALANCE control (R105) clockwise to center the pointer to approximately zero.

(    )         Adjust the A GAIN control (R9) to full clockwise.

(    )  (    )₁         Adjust the A GAIN control (R9) from full clockwise to full counter-clockwise.

(    )  (    )₂         Adjust the A BALANCE control (R105) until the pointer remains stationary.

· Repeat the above 2 steps * until no change is observed when rotating the A GAIN control (R9).

(    )         Adjust the A GAIN control (R9) to full clockwise.

(    )         Adjust the A ZERO SET control (R113) to center the pointer.

(    )         Repeat the above 2 marked steps * until no change is observed when rotating the A GAIN control (R9).

* * * * * * *

(    )         Set the MODE switch (S2) to the B position.

(    )         Adjust the B ZERO SET control (R114) to indicate 2.5 volts on the VTVM.

(    )         Adjust the B GAIN control (R10) to full clockwise.

(    )         Adjust the B BALANCE control (R106) clockwise to center the pointer to approximately zero.

(    )         Adjust the B GAIN control (R10) to full clockwise.

(    )  (    )₁         Adjust the B GAIN control (R10) from full clockwise to full counter-clockwise.

(    )  (    )₂         Adjust the B BALANCE control (R106) until the pointer remains stationary.

· Repeat the above 2 steps * until no change is observed when rotating the A GAIN control (R9).

(    )         Adjust the B GAIN control (R10) to full clockwise.

(    )         Adjust the B ZERO SET control (R114) to center the pointer.

(    )         Repeat the above 2 marked steps * until no change is observed when rotating the B GAIN control (R10).

(    )         Disconnect both VTVM leads from the OUTPUT terminals.

* * * * * * *

ATTENUATOR ADJUSTMENTS

Refer to Figure 4

Construction Manual, page 26

♦ Requires the use of an Audio Generator.

(    )         Connect a pair of test leads or a coax cable to the oscilloscope’s vertical input.

(    )         Connect the same pair of test leads or coax cable to the Electronic Switch’s OUTPUT terminals.

(    )         Adjust the Audio Generator frequency to 1 kHz.

(    )         Set the Audio Generator output to Square Wave.

(    )         Connect a pair of test leads or a coax cable to the Audio Generator’s output.

(    )         Adjust the Audio Generator’s output voltage for a desirable oscilloscope display.

(    )         Set ATTENUATOR B switch (S4) to the GND position.

(    )         Adjust the B GAIN control (R10) to full counter-clockwise.

(    )         Set the MODE switch (S2) to the A position.

(    )         Set ATTENUATOR A switch (S3) to the 10 position on the AC range.

(    )         Connect the same pair of test leads or coax cable to the Electronic Switch’s A-input.

(    )         Adjust the A GAIN control (R9) for a desirable oscilloscope trace.

(    )         Adjust trimmer (C3A) [top front] for a flat-topped square wave.

(    )         Set ATTENUATOR A switch (S3) to the 100 position on the AC range.

(    )         Adjust the A GAIN control (R9) for a desirable oscilloscope trace.

(    )         Adjust trimmer (C3B) [top rear] for a flat-topped square wave.

(    )         Disconnect the test leads or coax cable from the Electronic Switch’s A-input.

(    )         Set ATTENUATOR A switch (S3) to the GND position.

(    )         Adjust the A GAIN control (R9) to full counter-clockwise.

(    )         Set the MODE switch (S2) to the B position.

(    )         Set ATTENUATOR B switch (S4) to the 10 position on the AC range.

(    )         Connect the same pair of test leads or coax cable to the Electronic Switch’s B-input.

(    )         Adjust the B GAIN control (R10) for a desirable oscilloscope trace.

(    )         Adjust trimmer (C4A) [bottom front] for a flat-topped square wave.

(    )         Set ATTENUATOR B switch (S4) to the 100 position on the AC range.

(    )         Adjust the B GAIN control (R10) for a desirable oscilloscope trace.

(    )         Adjust trimmer (C4B) [bottom rear] for a flat-topped square wave.

(    )         Step the MODE switch (S2) counter-clockwise.

» There should be a different frequency square wave display at each switch position.

(    )         Disconnect the test leads or coax cable from the Electronic Switch’s INPUT terminals.

(    )         Set ATTENUATOR B switch (S4) to the GND position.

(    )         Disconnect the test leads or coax cable from the Electronic Switch’s OUTPUT terminals.

(    )         Set the POWER switch (S1) to the OFF position.

* * * * * * *

FINAL ADJUSTMENTS

Refer to PICTORIAL 2-8

Construction Manual, page 27

(    )         Install the cabinet top on the unit.

(    )         Set the POWER switch (S1) to the ON position.

               (Allow the unit to warm up for 5 minutes.)

(    )         Repeat the ZERO SET AND BALANCE ADJUSTMENTS section above.

(    )         Set the POWER switch (S1) to the OFF position.

(    )         Disconnect the line cord from the AC power lines.

 (    )        Calibration procedure is complete.