Giga-tronics GT 9000, Operation & Maintenance Manual

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5.3.12 100 MHz PLL
This circuit is located on the A14 PC board.
Corrective Action
1. Verify that the 10 MHz master reference input is being received.
2. Verify that the 100 MHz input is being received.
3. If possible, replace the circuit with a spare.
5.3.13 10 MHz Master Reference
The internal timebase is located in the rear left of the unit; the 10 MHz input/output circuit is
located on the 100 MHz PLL circuit board (A14).
Corrective Action
1. Verify that the signals from the internal timebase, and from the external timebase (if
any), are being received by the 10 MHz input/output circuit.
2. Verify that the 10 MHz signal from the input/output circuit is reaching the various PLL
circuits which require it.
5.3.14 1 Hz PLL
This circuit is located on the A15 PC board.
Corrective Action
1. Verify that the 10 MHz input is being received from the master reference.
2. Verify that the 10-12 MHz output is reaching the Ref /DC PLL.
3. If possible, replace the circuit with a spare.
5.3.15 IEEE-488 Interface/Timer Circuit
This circuit is found on the A2 PC board.
Corrective Action
Verify that these data and control lines have continuity to the rear panel connector and to the CPU. If
possible, replace the circuit with a spare.
5.3.16 Downconverter PLL
This circuit is located on the A16 PC board.
Corrective Action
1. First, investigate the coarse tuning output to the downconverter fixed local oscillator, as
follows: set the instrument to 1.000 GHz, ground TP2 on the REF/DC PLL board (A16),
and verify that the output frequency is accurate within 15 MHz.
2. Verify that the A16 board is receiving the 10 MHz reference input and the DC Sampler
IF input from the 100 MHz module (A201). Verify that the fine tuning output (A16
J1-65) is reaching the Output PLL (A18).
Model GT 9000 Microwave Synthesizer
5-14
Manual No. 120AM00250, Rev C, September 1998