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Chapter 8 HP 53181A Specifications
Time Base
8-4 Assembly-Level Service Guide
8
Note that power to the time base is maintained when the counter is placed in standby via the front panel switch. The internal fan will continue to
operate under this condition, to maintain long-term instrument reliability.
Time Base
Internal Time Base Stability
Standard
(0° to 50°C)
Medium Stability
Oven (Option 001)
High Stability Oven
(Option 010)
Ultra High Stability
Oven (Option 012)
Temperature Stability:
(referenced to 25°C)
< 5 x 10
–6
< 2 x 10
–7
< 2.5 x 10
–9
< 2.5 x 10
–9
Aging Rate
(after 30 days)
Per Day:
Per Month:
Per Year:
< 3 x 10
–7
< 4 x 10
–8
< 2 x 10
–7
< 5 x 10
–10
< 1.5 x 10
–8
< 1 x 10
–10
< 3 x 10
–9
< 2 x 10
–8
Turn-on stability vs. time:
(in 30 minutes)
< 2 x 10
–7
(referenced to 2 hours)
< 5 x 10
–9
(referenced to 24 hours)
< 5 x 10
–9
(referenced to 24 hours)
Calibration: Manual Adjust Electronic Electronic Electronic
External Time Base Input Specifications External Time Base Input Characteristics
Voltage Range: 200 mVrms to 10 Vrms
Damage Level: 10 Vrms
Threshold: 0 V
Impedance: 1 kΩ
Input Capacitance: 23 pF
Frequency: 1 MHz, 5 MHz or 10 MHz
(automatic selection)
Internal vs. External Time Base Selection:
Manual: Select Internal or External
Automatic: Internal used when External not present
(default)
Time Base Output Specifications
Output Frequency: 10 MHz
Voltage: > 1 Vpp into 50 Ω
(centered around 0 V)