[TenTec] Orion (565) FSK?

[Martin Sole]

So I thought I might have a play in the test this morning.

Well first I need to hook the Orion up to the pc. I have a keying interface
that has 2 transistors arranged to pull down the PTT and FSK lines so
connected these to the relevant pins on the Orion. PTT works but not FSK.
Grounding the pin of the connector directly does not cause a change in the
transmitted tone. Does the FSK pin want something other than a ground?
Should I see a voltage on this line in the ungrounded state?

Never tried this pin before so no real idea what to expect.

Anu ideas?

Thanks
Martin, HS0ZED