High Frequency Compensation and Risetime

Calibration Procedure For Oscilloscope Types 422 And 422Mod125B Page Navigation
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TB 9-6625-1200-24

(4) Adjust C511 (fig. 2) for eight major divisions between 2d and 10th markers (R).

NOTE

If b (2) and (3) above are performed, repeat a (4) through (6)

above.

(5) Adjust C527 (fig. 2) until 8th marker from 2d vertical graticule line is aligned

behind 10th vertical graticule line (R).

12. High Frequency Compensation and Risetime

a. Performance Check

(1) Connect oscilloscope calibrator SOURCE/MEASURE CHAN 1 output to TI CH

1 input, using 50 termination.

(2) Set both VOLTS/DIV switches to .05 and variable control to CAL.

(3) Pull out X10 MAG switch and set TIME/DIV switch to .5 SEC.

(4) Select oscilloscope calibrator FAST EDGE function and set to 100 kHz. Center

displayed pulse vertically on crt.

(5) Adjust LEVEL control for a stable display triggered on rising portion of pulse.

If displayed pulse does not have a square leading corner and a flat top with aberrations

within 1.5 minor divisions, perform b (1) below.

(6) Measure risetime, using standard risetime technique. Risetime will be 24 ns or less.

(7) Move connection from TI CH 1 input to TI CH 2 input.

(8) Set CH1-CH2 mode switch to CH2.

(9) Set TRIGGERING CH1 & 2, CH1, EXT switch to CH1 & 2.

(10) Repeat technique of (3) through (5) above. If displayed pulse does not have a

square leading corner and a flat top with aberrations within 1.5 minor divisions, perform

b (2) below.

(11) Repeat (6) above.

(12) Push in X10 MAG switch.

(13) Set oscilloscope calibrator to standby.

b. Adjustments

(1) Adjust R237, C237, L245, and L255 (fig. 3) in order for optimum square wave.