Hi Gordon,
I measured mine without any load and I had way too low output level on CLK2 and CLK1. It was a bit dependent from the frequency I tune in. Then I modified the code in the ubitx_si5351.ino inreasing the drive of the clock outputs. The DC voltage supply for the SI5351 supplies 3.3V, so there seems to be no problem.
I measured now with a HP54510A oscilloscope which has a greater bandwith than the Philips PM3335 analog scope I used before. I also used better oscilloscope probes to measure. Now I get 1.26Vrms when I tune on 10m band and 1.85Vrms on 80m. This should be okay. Now my receiving noise is also a bit louder on all bands but I still not receive any SSB Signal.
