Performance Tests
Performance Test 3
3-5
Reference Frequency Accuracy
Equipment required for this test:
• Frequency Counter
• Frequency Standard
To verify the accuracy of the internal frequency reference:
1. Warm up the UUT (continuous operation) for 24 hours, minimum.
2. Connect the 10 MHz output from the Frequency Standard to the EXT REF IN
on the Frequency Counter (rear panel) using a BNC male – male cable
assembly. Set the Frequency Counter for external time base reference.
3. Connect the REF FREQUENCY OUTPUT (on rear) from the UUT to the
Channel A input on the Frequency Counter using a BNC male – male cable.
Set the Frequency Counter input impedance to 50 Ω. See Figure 3-1 for
equipment connections.
4. On the UUT, enable the REF FREQUENCY OUTPUT at 10 MHz.
5. Set the Frequency Counter controls for a reliable and repeatable frequency
measurement.
6. Let the Frequency Counter to take several readings and settle. The settled
counter reading must be from 9.99999950 MHz to 10.00000050 MHz.
7. Set the UUT output to STBY. Disconnect the UUT REF FREQUENCY
OUTPUT from the Frequency Counter input.
Instrument
Frequency Counter
MHz
Ref Frequency
Output
hpn205.eps
Figure 3-1. Equipment Connections - Reference Frequency Accuracy Test
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