This is a ham radio transceiver status display indicator circuit that small and easy to build.
The application a Ham radio transceiver has 3 characteristic differential are
Firstly is Monitored status or Sometimes called standby, Means to turn on the Ham radio transceiver to To listen or wait for a call from either one, will has signal in Input signal or not.
Secondly is status that signal came in turn on may called Receive signal (Rx)
Thirdly is a transmit signal status called Transmit (Tx)
In circuit Figure 1 operation as standby status display indicator circuit or send only. By when connect at antenna line out of the ham radio transceiver to RF Input.
Figure 1 The Ham radio transceiver status display indicator
In normally status, when we do not push a RTT button (Push to Talk)To send signals D1, D2 no signal through Q1 and Q2, will also be OFF still, LED1 will glow because has positive current through R2 to LED to ground full circuit. The LED2 also go out because connected through Q2 which be OFF so not current flow.
When press a RTT button to send RF signal, then D1 will detect positive signal only. and D2 detect only negative that out of DCV, The negative signal will pass D2 to ground.
But the positive signal range in to drive Q1 and Q2 conduct pin C and E of Q1 Similarly, short-circuit it. Cause voltage between both lead is 0V, LED1 across has voltage drop across as 0V so go out.
The Q2 when ON will drive to LED2 glow up. And when release press key RTT will come back to new the standby status is LED1 glow. But LED2 go out.
How to builds
You do not make a pcb because this cirucuit is easy and small. So can put all parts in to the universal PCB board as Figure 2
The components List
Resistors ¼W +5%
D1, D2______75V 150mA Diodes__________1N4148
Q1, Q2_____45V 100mA NPN Transistor___2N3904