EMU-0202 noise floor


This graph (click for bigger) shows quisk receiving from an EMU-0202 which is hooked to an LP-PAN IQ Panadapter. The LP-PAN power is disconnected from DC power. The LP-PAN RF IN is not connected to anything (open). Both grounds are lifted on the EMU-0202. Both grounds are enabled on the LP-PAN. I adjusted the phase and gain for best image rejection.

If I enable grounds on the EMU-0202 but lift them on the LP-PAN, then when the LP-PAN is off there's about a 1 Hz pumping oscillation visible. If I connect RF IN to the K3 and turturn off the K3, the noise rises about 30dB at the two edges. So clearly I don't have optimal grounding.

With the LP-PAN power on, the noise floor rises to about -85 dB.

With the LP-PAN turned

With the LP-PAN turned on the noise floor goes up considerably; I think my kit may be improperly built.

Update: If I turn the internal gain pot all the way, it gets about 5dB better than this picture, but nowhere near the specs I read.


Other Reports

Here are reports from others with better methodology.