What signal do DEC models use to complete the circuit in the PTT relay?

DEC models utilize a path to ground to complete the circuit in the PTT (Push-To-Talk) relay. In this context, when the PTT button is pressed, it connects the circuit to ground rather than providing a voltage signal. This grounding action allows the relay to trigger, enabling communication by connecting the transmitter circuit.

Using a path to ground is a common approach in many audio and communication devices, where the act of grounding signifies that a function—such as transmission in this case—should be activated. The relay responds to this grounding signal by closing the circuit, thus facilitating the transmission of audio signals through the communication device.

The other options do not align with how the DEC models function in this scenario. Positive voltage would imply supplying power, which is not how the PTT relay operates in this instance. Constant current does not apply here either, as the triggering mechanism relies on a closure to ground, not a steady current flow. Likewise, signal interruption does not effectively describe the operational mechanism since the purpose of the PTT relay is to create a connection, not to interrupt a signal. Therefore, connecting to ground is the correct and effective way to complete the circuit in this specific application.