Gary @N8DMTSep 18, 2025
EtherKit Si5351A (Rev C) Mystery Solved: Root cause for the board’s +3.3VDC rail short to ground was the presence of J10 installed on the CCA. This shorts out the supply due to the use of the ECS-250-8-30B crystal which has GND connections on non-crystal corners. With jumper cut, the board works! Now to figure out a best use for this multi-output programmable square-wave test oscillator. Maybe write a LabVIEW front-end controller to maximize versatility?
#HamRadio #TestEquipment #FiltersNeeded
Show threadGary @N8DMT
Si5351 CLK1 Output: Adding two low pass and one high pass filters cleans this right up. Spurious are now > 50 dBc!
#HamRadio #TestEquipment #Si5351
Sep 18, 2025 at 4:18pmWeb
Show threadKA7OSep 18, 2025

@n8dmt

Uh, do you mean "Spurious are now < 50 dBc"? (I hope)

Show threadGary @N8DMTSep 18, 2025

@KA7O Sorry (RF slang). I use dBc in terms of spurious relative to the carrier’s level. Positive dBc (to me) means that the signal is below the relative carrier level. Negative dBc (rarely used) indicates that the signal is above the reference carrier level. (Yikes!)

Could have just said that the reference carrier is X dBm and the nearest spurious/harmonic level is Y dBm. I just guessed at the levels after quickly counting number of 10 dB steps on the spectrum analyzer display. Thanks & 73