The Orion manual warns the user not to directly connect the Orion's external
key line to older linear amplifiers made by Collins, Drake and Heathkit,
because the voltage on the linear's keyline is too high. Instead, Ten-Tec
states, a relay or transistor switch is _required_ between the Orion amp key
jack and the amplifier PTT keyline.

Does anyone know of a suitable device or schematic for this interface?
Preferably, it would be self-powered.

John, N9JG