Anyone have any idea what this is.
Welcome to the Technical Forum. I have not been able to identify this part. I am thinking is could be a 3.3 volt diode. I just have not found one with that marking code. Other people do monitor this site and also provide assistance. So someone might be able to identify this for you. Sorry.
Please, provide more information.
What device is this item from, model name?
Take a photo of the entire board.
Have you checked with a multimeter what kind of element it is?
It could be a transistor, a single diode, two diodes, etc.
Or is it burnt out?
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Hi James,
That S at the end of that marking in your first photo looks like it might be a logo, though I don’t recognize it. There are some zener diodes with part numbers that start with D3Z3 in link here but these are not in that same package type so I’m really not sure what you have there.
Thanks for the help. I am waiting to see if R&S is going to send me a manual so i can verify parts i found another part that is bad in that line also.
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1301 is for Linear Tech LT1301. Here is the spec https://www.analog.com/media/en/technical-documentation/data-sheets/lt1301.pdf
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I know that. I asked james_goos. 
I just wanted to add we do sell this part on this link:
The difference between the two options is temperature. The C in the part number is commercial temperature and the I is industrial. We have stock on both.