I've searched my FT-950 manual and also the Internet for specs on what voltage levels are expected on a PTT-line.Look on Page 14 of the FT-950 manual
."Interfacing to Other Linear Amplifiers"
Pin 2 of the "Linear Jack" is capable of
handling 30v DC @ 1A
or 60v DC @ @ 200mA.
Pin 2 of the Linear Jack is "TX SEND"
Pin 3 is Ground.
Good luck with your amp setup.
73, Ken AD6KA
You are talking about keying a linear.
He is asking about PTT. (I think)
Two very different things.