I don't know if this helps, but I dug out the most recent Keysight calibration certificate for this E5052A and there is a noise floor test done at 70 MHz with correlation set to 1.
I'm not sure what is involved with this test or at what power level it is run at but the numbers for the noise floor seem to be very good! I don't have anything here that can replicate this test although I could probably design a low noise LC oscillator that could get close at a 1 MHz offset.
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I generally design wideband single loop synthesisers up at VHF through UHF and the E5052A is easily good enough for stuff like this.
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