1、Lessons Learned Entry: 0304Lesson Info:a71 Lesson Number: 0304a71 Lesson Date: 1993-09-15a71 Submitting Organization: JPLa71 Submitted by: A. G. GussnerSubject: SIR-C Low Noise Amplifier Recovery Time too Long Abstract: Excessive Low Noise Amplifier (LNA) recovery time had not been detected because
2、testing had been done in transmit-only or receive-only modes. Hardware should be functionally end-to-end tested. Early module level functional tests should be performed to detect RF timing/leakage issues.Description of Driving Event: When the C-Band pulse from the transmitter was present in the ante
3、nna panel, the Low Noise Amplifier (LNA) in the receive chain had a long recovery time of up to 200 microseconds. The transmit/receive module of the antenna received transmit pulse leakage into the LNA which shifted the operating bias and caused the long recovery time before the LNA was enabled. All
4、 previous testing of the panel had been done in transmit-only or receive-only modes. Correction of the problem required extensive rework of the panels. Covers, harnesses, and printed wiring boards were removed to gain access to the transmit/receive modules. Then two resistors were replaced and five
5、capacitors were removed from each of twenty-eight modules in each of the nineteen panels.Additional Keyword(s): RF Performance VerificationReference(s): PFR #56187Lesson(s) Learned: Hardware should be functionally end-to-end tested.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or n
6、etworking permitted without license from IHS-,-,-1. End-to-end system tests to simulate actual use must be performed as early as possible in the test sequence.2. Early module level functional tests should be performed to detect RF timing/leakage issues.Evidence of Recurrence Control Effectiveness: N
7、/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1993-09-02a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
