Frank,
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my measurement setup has been described already in my FIRST posting on this topic:
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"
Measurement with a TinySA Ultra connected via 50dB (20dB + 30dB) attenuators.
Adding another 30dB of attenuation does not make a difference in the measurement result: The TinySA will then keep its internal attenuator at 0dB, but the spurs will still be -28dBc.
Reducing Drive to 50 will reduce the spurs to -31dBc."
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BTW: using a TinySA instead of a TinySA Ultra provides exactly the same results.
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I have built at least a dozen transceivers over the last years: none showed this kind of spurs.
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To eliminate the voltage regulators U6 and U7 as the origin of the spurs, I added the missing 22uF tantalum capacitors on their outputs --> no difference, spurs are still there.
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BTW:?the solution is not "shoot the messenger".
--
73, Joerg - DB2OO
