I like working with Arduino and one outcome is a Sequencer to control the PTT to the different circuits. Normally the sequence goes like this:


Sequncing the PTT to the different circuits, is for protecting the relays and amplifiers to not get damage under the shift from RX to TX.
What I think could be nice to have, when implementing a sequencer:

  • Min. three outputs to control RX/TX, PA and antenna relay.
  • The delay time can be changed to meet different systems.
  • Sense input from antenna relay of shift state.
  • Display on LED’s of sequence output timing or error.

My construction has 4 output’s, so that a transverter also can be controlled when needed. The Hermes has outputs that can be controlled when using different bands, to enable or disable the sequencer that is used for different antenna systems. So it is easy to control when having more than one antenna / band in use on the transceiver.
Delay time can be changed with jumpers on the PCB, so that different systems can be used with small or big antenna relays / amplifiers, and not to shift when power is on and save relay contacts.
One thing I have implemented as extra in the system, is a sense input from the antenna relay. It is critical that the antenna relay, with maybe a preamp, is in the right shift position when applying power, and not damage the preamp / relay. The input signal can be reversed on sense (High/Low), so that different relays can be used.
Outputs can be displayed on 4 LED’s and PTT activity / Error is also shown with an extra LED. When blinking, the signal is ready for TX and when there is an error, the LED is on all the time. Reset of failure on the sense input that gives a error, can only be set back to normal when the sequencer is powered off/on.
Sense input can be disabled with jumper, to be ignored.
When sense input is enabled, it checks shift state, when power first time is applied to the circuit.

As told before the sequencer is made with Arduino, to program a Atmel processor like one in Arduino Uno. The PCB is made for easy soldering with normal components.

If you like a fully mounted and programmed PCB – look under buy/sell, and then contact me. (comes later)

If you would like to build it yourself, look at schematic – PCB layout and program, how to make it.

Schematic: Sequencer Schematic pdf

PCB: Sequencer PCB pdf

Program: Sequencer.ino (comming)