Transwerter 70cm -tego nie kupować
From ON4KST today:

21:26:11 G4DBN Neil 2+23+13 (G4RQI) Ukrainian transverter oscillating on 424MHz, 3 watts..... not good, hence FM rig

However: oscillating of transverter must have some reason - broken SMD capacitor? bad design? Too wild transistor? When such trouble will be found, there is from my prespective no reason to say it is a completely wrong desing.
For example FT847 on 70cm sometime oscillate as well as if connected into PA with GS35 - albeit on 432MHz the PA could be matched, but somewhere above 445MHz such PA may have unlimited SWR...