Today's modern transverters use very low-noise front-ends to provide the best signal to noise ratio possible. But these low-noise front-ends will not survive the high transmit power levels found in most transverter systems. Especially during the switching from receive to transmit and back to receive. A sequencer is needed to protect these low-noise front-ends from the potentially destructive transmit power levels, and normal relay contact bouncing found in every RF antenna change over relay. The SEQ-1 provides four sequenced open collector outputs to control your transverter sub-systems switching requirements. Each open-collector output is capable of switching up to 35 volts at 600 ma continuously. Using open-collector outputs allows for direct control of relay coils. Using additional analog circuitry, other switching schemes are possible with the SEQ-1. Also provided is the ability to invert the active output state of any of the four open-collector outputs.

The sequencer is enabled by using either the Low-Enable input, or the High-Enable input pins. The Low-Enable input is a connection taken to ground to cause the sequencer to activate. The High-Enable input connection requires a positive input voltage from +2.0 to +14 volts to cause the sequencer to activate.

Provisions have been made to allow the user the ability to reprogram the time delay value used to control the sequencer on/off steps. This allows the user to fine-tune the delay time for the environment being controlled. For example, if the RF switching is all solid state, like PIN diode switching, then a smaller time delay value would be appropriate. If you are using mechanical relays, a longer time delay would be required to allow for contact settling. What's more, the time delay value can be programmed right in the circuit. No need to remove the SEQ-1 from your system to change the delays. The default delay value is 32 milliseconds for each step, but is programmabel from 4 msec to 128 msec per step.