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1780R-Series Service Manual
1–15
Table 1–7: Vectorscope Vector Display (Cont.)
Characteristic
Performance
Check Step
Supplemental InformationPerformance Requirement
Variable GAIN Range +14 dB to –6 dB of 75% color bar
preset gain.
Unterminated color bar signal can
be brought to appropriate targets.
Burst from a triple terminated
signal can be moved to the
compass rose.
52
Max Gain >X5.
Variable GAIN Phase Shift ±1_ as gain is varied from +3 dB
to – 6 dB.
53
Table 1–8: Vectorscope X-Y Display
Characteristic Performance Requirement Supplemental Information
Performance
Check Step
Input DC coupled differential inputs
through rear-panel connector.
Input Amplitude 2 to 9 V peak-to-peak. Adjustable full scale deflection
0 dBm to +12 dBm for 600 W
system. Factory set to 0 dBm.
Maximum Input Voltage ±15 V combined peak signal and
DC.
Frequency Response DC to >500 kHz. 3 dB point. 55
X and Y Input Phase Matching < a trace width of separation at
20 kHz.
Single-ended. Phase matching
above 20 kHz may be improved
by adjusting Vertical Deflection
Amplifier VHF Compensation.
54
Table 1–9: Vectorscope SCH Phase Display
Characteristic Performance Requirement Supplemental Information
Performance
Check Step
Accuracy
Absolute ±5_ phase at 25_ C.
56
Relative ±2_.
Acquisition Time ≤1 sec. 56
Display Phase Error caused by CRT
Geometry Variations
±1.25_ calibrated for zero display
phase error at zero SCH phase.