HP 8924E, Сборка

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Chapter 14, Diagnostics Descriptions
Description of RF Diagnostics (RFDIAGS3)
N:\mkt\MANUALS\HP8924C\ALR\diagnos.fb
Reference Assembly A27
Table 122 A27 Reference Tests
Measurement Explanation and Suggestions Measurement Point
10 MHz Lock
Detector The lock detector on the internal 10 MHz reference
oscillator is read. Latch:refs_10MHz_sense
10 MHz Time
Base Count The frequency of the 10 MHz reference is measured
by the counter. Since the reference being measured is
also the reference for the counter, a valid counter
reading indicates only that the counter is functioning
but is meaningless as to accuracy. If the counter loses
its reference, this measurement will timeout and the
diagnostic test will stop. If this happens, trace the 20
MHz signal from P3-13 of the A27 Reference to P3-
29 of the A37 Measurement. Counter:REF_10MHZ
1 GHz Oscillator
Lock Detector The lock detector on the 1 GHz Loop is read. Latch:refs_1GHz_sense
1 GHz Enabled
Output Level The RF detector on the 1 GHz output with the 1 GHz
switch closed is read. DVM:REF_1GHZ_DIAG
1 GHz Disabled
Output Level Open the switch that routes the 1 GHz signal to the
output of the board. The detector is after the switch so
it should detect that the signal is no longer there. A
long wait is needed before measuring the detector. DVM:REF_1GHZ_DIAG
500 MHz
Output Level The RF detector on the 500 MHz output is read. DVM:REF_500MHZ_ DIAG
200 kHz or 1
MHz Output The Test Set is queried as to whether the reference
output is set to 200 kHz or 1 MHz. The 200 kHz or
1 MHz outputs can be turned off by holding the out-
put flip-flops in reset. The output detector is read with
the output in the reset condition and in the normal
operating condition. (Note: The Latch name is correct
despite the “250_kHz” indication.) Latch:refs_250_kHz_sense
10 MHz Fine
and Coarse
DACs It is not possible to actually measure the 10 MHz fre-
quency change caused by changing the DAC setting.
Each DAC is set to a low value (0) and a high value
(2000), and checked to make sure that the loop stays
locked. Latch:refs_10MHz_sense