Ludwig,
thank you very much, now I understand the unusual principle of this power supply, with a linear regulator only for the start, and PWM regulator for a normal function.
Luckily, it is not urgent, TRX is working at 12V without any problems :-) and I like my QMX. I'll probably purchase another 3.3V board later.?
Mni TNX es 73, Stojan
