This 4-way PTT sequencer is product designed for PTT switching from one input to four outputs with different (fixed) delay. You can split PTT signal to 4 independent devices with different timing: LNA, PA, RF relays etc. This device also protects your PTT output from external accessories. There is optocoupler isolator between PTT input and all four PTT outputs. Outputs are switched to ground when PTT is active. There are FET outputs without any additional delays.

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Applications
Sequencer
Sequencer Timing
Schematic example
Product details

Applications

Sequencer

assembled version in box

assembled board version

Sequencer Timing

Here is an example of a timing measurement. The first state change is from RX to TX, where PTT IN is connected to ground. It triggers a timing circuit where T0 is no delay, T1 is delayed by 60 ms, T2 by 120 ms and T3 by 180 ms. The outputs are like switches to ground - the active output is connected to ground. When transitioning from TX to RX, reverse timing occurs. T0 is still 0 ms (it is analog connected to PTT IN), T1 is delayed by 180 ms, T2 by 120 ms and T3 by 60 ms.

Schematic example

There is an example for positive voltage switch with no additional delay. You can use relay but do not forget to additional delay by relay.