Tabor 8020, User Manual

Page: 82 / 111

5 . Disconnect the 8020 OUTPUT from the distortion ana-
lyzer and reconnect it to the counter input.
6 . Change 8020 Output setting to squarewave.
7 . Verify that the frequency reading on the counter is 10.00
Hz +/-.1 Hz. If reading is not within range, repeat steps 7-3-4
and 7-3-5 until all adjustments are within the specified range.
7-3-6. Trigger Start Phase Adjustment
Equipment: DMM
1 . Change 8020 front panel settings as follows:
Output setting to Triangle.
Trigger setting to Gated.
Amplitude setting to 15.0 V.
2 . Connect DMM to 8022 output connector.
3 . Set DMM and select R73 for a DMM reading of 0 V +/-.1
V.
7-3-7. Amplitude Adjustment
Equipment: DMM (RMS)
1 . Change 8020 Amplitude setting to 15.0 V.
2 . Change 8020 Frequency setting to 1.000 KHz.
3 . Set DMM to ACV measurements and connect 8020 OUT-
PUT through a 50 ohms feedthrough termination to the
DMM.
4 . Set Output waveform and perform adjustments, on the am-
plifier board assembly, as in the following table:
OUTPUT ADJUST- RERQUIRE
WAVEFORM MENT DMM READING
Sine R39 5.31V +/-20mV
Triangle R38 4.33V +/-20mV
Positive Pulse R127 3.75V +/-10mV
Negative Pulse R126 3.75V +/-10mV
Square —- 7.50V +/-20mV
7-3-8. Offset Adjustment
Equipment: DMM, 50 ohms feedthrough termination
1 . Change 8020 frequency setting to 1.000 KHz and ampli-
tude setting to 1.00 V.
2 . Change 8020 Offset setting to 7.00 V and turn offset on.
3 . Set DMM to DCV measurements and connect 8020 OUT-
PUT, through a 50 ohms feedthrough termination to the
DMM.
4 . Adjust R99, on the amplifier board assembly to give a read-
ing of 7.00 V +/-50 mV on the DMM.
5 . Change 8020 offset setting to -7.00 V.
6 . Verify that DMM reading is -7.00 mV +/-50 mV. If not
within range re- adjust R99 to compromise between the two
readings.
7-3-9. Squarewave Response Adjustment
Equipment: Oscilloscope, 50 ohms feedthrough termination
1 . Temporarily install C23 - 6.8 pF and C21 - 15 pF.
2 . Change 8020 Frequency setting to 1.000 MHz.
3 . Change 8020 Amplitude setting to 15.0 V.
4 . Connect 8020 OUTPUT connector, through a 50 ohms
feedthrough termination, to the oscilloscope input.
5 . Set oscilloscope to 20 uS/Div. and adjust the Vertical con-
trol on the oscilloscope to display the square waveform in
exactly 6 vertical divisions.
6 . Change oscilloscope setting to 5 nS/Div.
7 . Adjust C62, on the amplifier board assembly for the best
rise/fall times and for minimum overshoot and undershot. If
necessary, select C23 for best pulse response.
8 . Change 8020 Amplitude setting to 1.50 V and verify that
the response is within the limits. If necessary, re-select C21
for best pulse response.
7-3-10. Sine Flatness Adjustments
Equipment: Oscilloscope, 50 ohms feedthrough termination
1 . Change 8020 Function setting to Sine.
2 . Change 8020 Frequency setting to 100.0 KHz.
3 . Change 8020 Amplitude setting to 15.0 V.
4 . Connect 8020 OUTPUT, through a 50 ohms feedthrough
termination, to the oscilloscope.
5 . Adjust oscilloscope controls to display the Sinewave with
exactly 6 vertical divisions peak to peak.
6 . Change 8020 Frequency setting to 20 MHz.
7 . Select C6 (approximately 10 pF), on the amplifier board
assembly, so that the sinewave amplitude on the screen will
be within the range of 5.1 to 5.3 vertical divisions.
Model 8020 Adjustments
Page 7-3