You have several possibilities:
1. switch PTT via the 3,5mm plug
2. set the jumper inside to switch to TX via +12V on the coax
3. HF-Vox - is active any time (to protect the transverter of TXing into the RX part )
But there is a manual that can be downloaded from Hrisijans web site where all the above mentioned points are explained.
73 de Johannes