braudoux wrote on Jan 25^th, 2016 at 4:04pm:

Hi Guys, Does anyone know: - if there is a Yaw Damper switch in E-3A cockpit  ::) - if yes, where darned is it?  :D I experienced some crazy "up and down tremors" during my last flight (same as B737 when Yaw Damper is disconnected), so I am wondering if it is not the same symptom :-/ Thanks for help Bruno

On page 43 of the ‘707 Captain’ FLIGHT MANUAL Part II – Aircraft and Systems (cs707_manual1.pdf), under the heading of O04. HYDRAULIC POWER SYSTEM, it lists the Rudder Switch instructions:

ON: Opens rudder boost shutoff valve.
OFF: Shuts off rudder boost pressure and series yaw damper.

So that's the switch you need to make sure is ON.

What you are describing sounds like a Dutch Roll, which happens when the 707 (or any aircraft) is too high for its current gross weight. I usually descend until it gets more stable. ;)