[Elecraft] VHF PA and HF PA on the same K3 - how to?

[Kjeld Holm]

Dear Elecrafters,

I am about to run my K3 with INTERNAL 144 MHz transverter with two external
PAs for HF and VHF respectively. 

For now I am using the KEY OUT connector for the keying of the HF PA. 

How can I get a key out signal for my coming VHF PA? 

To the best of my knowledge the two amplifiers have different voltages on
the connection. So I believe I cannot just use an Y-splitter. 

I see on page 19 in the manual for K3:
For transverter keying, you can use KEYOUT-LP
signal (pin 10 of the ACC connector) or the KEY
OUT jack (RCA).

But how about the potential and other details on this connector? 

To the best of my knowledge my coming VHF PA has 5V on the center pin of its
key in connector. 

Vy 73 de OZ1CCM, Kjeld