Power Measurement Error of SA124B

Hello
I am using SA124B spectrum analyzer for power measurement of a specific frequency in my project. Initially it was doing wonderful job and providing accurate reading. However, now i am facing issue of inaccurate power measurement by my device. A signal of -15 dBm at 6 GHz freq is being measured by my device as -70 dBm/6GHz. I have checked it with the latest version of spike (3.22), problem still persists. second thing which i observed is the value of amplitude is dependent on the ref offset level. for example with 0 dB offset amplitude is -70 and with 50 dB offset amplituse is -20dBm. Is there anything i am missing?

Sounds like a problem I just had, which I think is down to the input connector centre pin. I applied a bit of sideways pressure and the signal shot off. Sent it off to my local retailer for repair last week and waiting for some feedback.

Thanx Dr Dom,but i dnt think so there is any issue with connector … as i dnt remember any such incedent which would have damaged the connector. How to check it actually?

Ash,
It sounds like we may need to look at your SA124B. If you have the equipment, generate a CW signal at 25 MHz, 1 Ghz, 3 GHz, 6 GHz, and 10 GHz, around -10 dBm with a 0 dBm reference level and 100 kHz span. If any of them read more than a few dB off, we will need to repair your SA124B. Email support @ signalhound.com for details.

I tested my unit in a similar way to what Justin has described, I used a swept source and put the SA124B on max hold and let it build up a picture. If it is cracked/open circuit input pin you will see an increasing signal level with frequency. Foltronics in Holland did a great job quickly fixing my unit and it is already back with me – thanks guys! 🙂

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