Before today’s modern transceivers, radio amateurs used separate transmitters and receivers. They were usually very large, vacuum tube designs, developed a lot of heat, and were quite a bit more sensitive to drift, filtering, hum, and adjacent channel interference.
Many amateurs continue to “work” with these designs for many reasons. If you build a transmitter kit such as we offer on our web site http://www.pastimeprojects.com, you have to figure out how to connect it to a receiver and be able to share a common antenna.
It’s really fun to connect it with a ‘modern’ tube type receiver, such as the Collins, Hallicrafters, National, Drake and others. EF Johnson sold a automatic switching TR switch, model 250-39 which worked very well. Do a search on the internet for more information. There are come up for sale occasionally; be careful – the condition of older equipment is always a concern.
Pastime projects is working on a new TR switch for use between vacuum tube type transmitters and receivers. “New” is not the proper term, as our design will be very similar to a published design from the 1960’s. We have a couple prototypes on the bench. We also have a rebuilt Johnson Model for reference. Watch for introduction on our web page soon. As always, write if you have comments. 73 Glenn W8JZI http://www.pastimeprojects.com or pastimeprojects(at)yahoo(dot)com
Just a final thought: These designs use a vacuum tube as a switch and switching between a low to moderate powered tube type transtmitter and a vacuum tube type receiver is automatic. Makes for very smooth transition. This is not a mechanical relay system which requires manual switching…
