AnsweredAssumed Answered

8970B Problem

Question asked by mhtplsh on Dec 13, 2007
Latest reply on Jan 15, 2008 by mhtplsh
I hv following problem with my 8970B.
In the frequency range 97~102 Mhz the equipment is showing more noise.

First i set the frequency from 78Mhz to 118Mhz in the step size of 2 mhz.
Than i connect the test cable from  noise source 346B to input of 8970B.
Then i press the calibrate button twice. Then i press the noise figure & gain button. I tested the DUT under this conditions. It was not showing proper gain & noise figure, Hence sent the equipment to HP service station at Banglore.

I got the info from service station that the RF connector is defective so there is some clip around 800 Mhz. After changing connector, calibration  will be required.
I agreed for this in hope of getting the equipment fully perfectly done. I was billed almost US$ 750 for this. This amount is quite high according to Indian standards.
Then i received the equipment.  I tested it after few months as there was no development job on my hand. I found that it is showing 10db more gain than shown by vector network analyzer also made by HP.
During the test of just testing cable the noise figure from 78~118 Mhz, for  97mhz to 102 Mhz band noise figure was showing quite high. Even after changing the test cable also we got the same results. 
Hence i sent back the equipment to HP. I got the call from agilent about the service problem. I explained it to the agilent engineer.
Yesterday i got the equipment back. 
But this time i am getting some new problem.
The gain in the band of 88~108 Mhz is showing ok except 97~102 Mhz. In the 97~102Mhz gain is less & noise figure is quite high during DUT test.
During only test cable test ( without DUT) from 78~118Mhz also the 97~102Mhz noise is quite high. This is just testing passive cable. So unable to understand why it is happening.
Previously the gain was  showing 10 db more but this time it showing ok except 97~102 Mhz. This is difference between two service.
kindly let me know, what can be the problem or solution to this problem.  

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