I had a need for an RF sequencer for my 432Mhz system, so I decided to have a go at making an RF sequencer based around an Arduino Uno and a four relay top hat card available from many internet sources.

Anybody that knows me will know that software programming is not one of my strong points to be honest I am useless at it.

If you follow this article any further you do so entirely at your own risk. I will not be responsible for any damage however caused.

But if I can do it anybody can, so good luck.

Input 2 is used for PTT detection which then sequences a change of state of all four relays with a delay between each relay switching

The four relays switch the following on transmit and do the reverse on receive.

Low nose preamp (LNA) off

Transverter from RX to TX

Power Amplifier enable

And finally PTT to the Transceiver

The sequencer has the following features

Pin 9 = Manual override for Relay 5 via switch. This turns the LNA power on and off

If LNA switch is off it allow automatic control (Relay 5 inverted) via the sequencer to the LNA power off during TX

Relays 6-8 automatic

Non-blocking timing

Pin 3 switches PA LED on in TX off in RX

Pin 4 switches Transverter status LED on in TX off in RX

Pin 13 LNA status LED on when LNA in RX or off on TX ,or switched off via front panel switch