RX-TX unit with Sequencer amplifier LDMOS MOSFET tube For Sale -

RX-TX unit with Sequencer. This unit is intended to provide the switching of HF amplifier between receive and transmit modes. When PTT input goes low, the relays directs the signal from transceiver to PA input and from PA output to LPF (or antenna). Thanks to sequencer, when you decide to transmit, the PA output relay is energized first. Then, after 100 msec delay, the input of PA is connected to transceiver. Then, after next 100 msec delay, transceiver is keyed to transmit mode. Transmit to receive sequence is vice versa. First, transmit mode of transceiver is released, then after delay the input relay disconnects radio from PA input and then the LPF (or antenna) connected to transceiver. SSB operation PTT input must be connected to a footswitch or microphone PTT switch. Microphone element connected to the radio in the normal manner. PTT OUT connected to transceiver PTT input port. VOX should be switched off. When PTT is asserted the sequence is started . CW operation To be able to use this sequencer for CW operation the radio should be able to work in no “break-in” or vox mode, i.e. upon activating the CW KEY input of the radio it should NOT go into transmit (preferable only sidetone should be activated). A separate radio PTT input must be available for commanding the radio to go into transmit and only then RF power should be output following the CW KEY input. In addition the CW keyer should provide an outgoing PTT signal (low active) signaling start of CW message with sufficient “tail/hang” time such it wouldn’t go inactive between CW characters. For instance the Winkey device from K1EL is perfectly suited. CW output of the keyer needs to be connected to the KEY input of the radio and PTT keyer output to the PTT input of the sequencer. When PTT is asserted (start of CW) the sequence is started. In addition, the ALC voltage port is provided to control the maximum output power of transceiver and +15V in TX mode could be used as BIAS voltage for amplifier. Led “On AIR” may be connected to indicate the transmit mode.

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