question are you trying to replace turret rotation or elevation with the servo?

if your doing elevation There are two other options
1. use a 6 channel radio and run the servo off of the RX
2. use a y connector to connect both the servo and the DMD to the RX then leave the DMD motor disconnected you will still get the sound effect but movement would be handled by the servo if your doing this for elevation its best to use a servo delay module so that when you let go of the stick so you can fire the main gun does not move much.

If your doing turret rotation then option 2 would work well.

Here is a link to a How-To on the H*E*A*Tweb site
http://heatarmor.com/joomla/index.ph...&Itemid=29

hope that helps