Yes Armin, the transverter seems to have less noise.
But I am not yet satisfied with the large signal behavior. I have provided two anti-parallel protection diodes at the 28mhz input of the converter because the RF VOX activates the attenuator after a few milliseconds delay. I will replace the diodes with 2 BA70-04 with 2 diodes each in series. This should improves the IM3.
You don’t have the problem if you use the PPT output of the KX2. But then you have to make a secure connection, otherwise you will destroy the FET from the preamplifier.
Since I am sometimes very excited when activating, I chose the safe solution with the RF Vox. The circuit itself has proven itself and the RF VOX is hardly noticeable: https://youtu.be/8dYwF_sNEew
The TCXO works very well. No noticeable drive and the offset is less the 10Hz. The offset of the original XO is -400Hz and drifting up to +100Hz, when the transverter warms up.
Good luck with the handicrafts.