HP 70427A User Manual page 440

Internal Operation
Table 13-4
External Operation
10 MHz Timebase (A5Y1)
The internal timebase is a 10 MHz, low noise, oven-stabilized, third overtone
SC-cut VCXO from Wenzel Associates, Inc.
The electronic frequency control (EFC) has a maximum input voltage range
of ±5 V, with a 0.05 ppm/V tuning sensitivity.
The internal timebase has two noise options, the standard unit, and the
selected low noise special which improves the noise inside of 300 Hz carrier
offsets.
10 MHZ Timebase (A5Y1)
Offset Std.Uni
Frequency t
1 Hz –100
10 Hz –130
100 Hz –150
1 kHz –160
Phase noise is in dBc/Hz. The last two columns are the timebase noise
requirements to meet the customer specification and the Typical standard
noise performance.
The timebase is Mu-Metal shielded to minimize spurious pickup.
The signal kill (10 MHz_CNTL) feature on the timebase allows the
microprocessor to shut off the 10 MHz for diagnostic checks.
The oven temperature status can be monitored by the module via the oven
monitor port.
The timebase output level is +10 to +13 dBm into 50Ω. This signal is routed
to the rear panel. A jumper cable must be connected between the 10 MHz
OVEN OUT and the 10 MHz IN for internal timebase operation.
An external 10 MHz reference may be connected to the 10 MHz IN
connector. The 10 MHz input requires a signal of 10 MHz, ±1 ppm. The
input level is +7 to +14 dBm.
Low Timebase Performance
NoiseUnit Requirements
Specified
–110 –95
–140 –125
–160 –145
–165
HP 70427A/HP 70428A User's Guide 13-5
Block Diagram
10 MHz Timebase (A5Y1)
Typical
–100
–130
–150