Giga-tronics GT 9000, Operation & Maintenance Manual

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5.2 Malfunctions
It is important to establish under what circumstances a malfunction does (and does not) occur.
Failure may occur in only a portion of the frequency range or level range, or only in a particular
operating mode. Explore different settings and modes in order to find the limits of the
malfunction. It may be found that a malfunction occurs only during remote control operation
(see Section 5.2.6).
Six major areas of potential failure are addressed in this procedure. Each problem area is
analyzed with a reference to the troubleshooting notes included in Section 5.3.
5.2.1 General Failure
Symptoms: The unit does not respond appropriately to commands from the front panel controls
or IEEE-488 interface; the readouts are blank, erratic, or fixed in one state.
Recommendations:
1. Check the power supplies (see Section 5.3.1).
2. Check the computer (see Section 5.3.2).
5.2.2 Loss of RF Output
Symptoms: No measurable power is present at the output connector, regardless of the RF level
setting. The front panel LEVEL indicator may or may not be lit.
Recommendations:
1. Check the power supplies (see Section 5.3.1).
2. If the LOCK LED is not lit, check the YIG oscillator (see Section 5.3.4).
3. If the LEVEL LED is not lit, check the Microwave Module (see Section 5.3.5).
4. If the LEVEL LED is lit, check the 10 dB step attenuator (see Section 5.3.3).
5.2.3 Incorrect Output Level
Symptoms: Output power is at a level other than that selected by the RF level setting. The front
panel LEVEL indicator may or may not be lit.
Recommendations:
Before proceeding, be sure that the selected RF level is within the capability of the GT 9000.
Although it must meet a maximum power specification, the actual maximum will be somewhat
in excess of this, and will vary for different frequencies. When exceeding the normal power
range, the LEVEL indicator may go out and the RF output may fall below the level requested.
1. Check the RF Output connector.
2. Check the power supplies (see Section 5.3.1).
3. If the level error is a 10 dB multiple (e.g., -20 dBm instead of +10 dBm), check the
10 dB step attenuator (see Section 5.3.3).
4. Check the microwave module (see Section 5.3.5).
5. Check the detector (see Section 5.3.6).
Model GT 9000 Microwave Synthesizer
5-2
Manual No. 120AM00250, Rev C, September 1998