TR (Transmit-Receive) switches have always been of interest to me, particularly as a CW operator. TR switch issues fall into these basic categories:

• Tube/High-Power Transmitters, Receivers, and Power Amplifiers
• Solid State Applications
• QRP Applications

QRP creates applications for TR switches. As someone who is constantly building simple transmitters and receivers, particularly QRP, there is always the question of how to integrate them together so they can actually be operated. The same is true with vintage rigs, however, except power levels and voltages in use are much higher. If you have separate transmitters and receivers, you need a TR switch arrangement of some kind to be able to use them together. For voice, a simple TR relay may suffice, but this will not be satisfactory for CW use.

• The w3lyp TR switch I once built and used with vintage rigs
• The Johnson TR-1 electronic TR switch that was stolen from my NY shack with other gear
• The K8IQY MagicBox (external site) that is offered as a kit by The FOur State QRP Group