I can confirm that this adapter was working for my PW3 serial jailbreak.
(XCSOURCE FT232RL 3.3V 5.5V) Search for FT232RL on amazon or eBay.
This chip can handle 1.8v. The converter has a jumper for selecting the voltage,
just unplug the jumper and connect it to your PW3. I have checked the voltage with a meter.
The chip automatically adapts to it to 1.8V.
Thx knc1 for your help