Although rare, some radio applications may require higher voltages or current than what the PTT line on some of our products can provide. The higher voltages or current can cause damage to the PTT line circuit.
To work around this, you can connect the PTT line from the JPS equipment to a 5V relay (with power supply) and a Flyback Diode.
- 5-volt relay with less than 100mA of coil current[i]
- Flyback Diode[ii] must be used to protect the PTT line of the JPS equipment
[iii] The NXU-2B and the QMT-1B do not require the flyback diode and relay as described in the document for the following reason. The NXU-2B and the QMT-1B use hardware relay contacts for PTT output whereas previous generations used a solid-state (open drain transistor) keying output. There is a jumper selectable solid-state output available on the NXU-2B and the QMT-1B as well, but the default is to use the relay for PTT. The relay allows for higher keying voltages and currents than the solid-state output. Refer to the appropriate NXU or QMT manual for your product.