TB 9-6625-128-24
13. Common Mode Rejection Ratio
a. Performance Check
(1) Set TI controls to the following:
VAR (both)
CAL
VERTICAL MODE
ADD
CH2 INV
IN
Input Coupling (CH2)
GND
50 μs
TIME/DIV
TRIGGER NORM/AUTO
AUTO
TRIGGER SOURCE
CH1
X-Y button
OUT
(2) Connect the oscilloscope calibrator to the TI CH1 and CH2 input connectors
through a 50 Ω feedthrough and dual input coupler.
(3) Set the oscilloscope calibrator for a 50 kHz sine wave at 800. Set the OUTPUT
to ON. Adjust the output to obtain 8 div of vertical deflection centered on the TI CRT.
(4) Set the TI CH2 GND button to OUT and set VOLTS/DIV (both) to 10 mV.
(5) Adjust either the TI CH1 VAR control or TI CH2 VAR control for a minimum
TI display amplitude while leaving the other control in detent (whichever provides the best
Common Mode Rejection).
(6) Verify the TI display amplitude is ≤1.6 div (exclude trace width).
(7) Set oscilloscope calibrator to standby. Disconnect the test setup.
b. Adjustments. No adjustments can be made.
14. Calibrator
a. Performance Check
(1) Connect the TI CAL output connector to the CH1 input connector.
(2) Set the TI CH1 VOLTS/DIV and VAR controls for 8 div of vertical deflection on
the CRT.
(3) Disconnect the TI CAL output connector from the CH1 input connector.
(4) Connect the oscilloscope calibrator CH1 to the TI CH1 input connector.
(5) Set oscilloscope calibrator voltage output for 1 kHz, 2 V. Adjust oscilloscope
calibrator knob located below the EDIT FIELD key for 8 divisions of vertical deflection on
the TI CRT. Verify the oscilloscope calibrator Err readout indicates within 2.0%; if not
perform b below.
(6) Set the oscilloscope calibrator output to standby.
(7) Set the TI CH1 VAR to CAL.
(8) Connect the TI CAL output connector to the frequency counter A input
connector.
