electromechanical protection circuits ensure that a transmitter can only be connected to an antenna that is tuned to the same frequency.
"The Dawn of Amateur Radio in the U.K. and Greece A Personal View"
Norman F. Joly
No, there was only one possible thing of appreciable value; the one thing that Paul Brennan hoped to gain was the device over which they had worked through all the long years to perfect: The Holden electromechanical Educator!
"The Fourth R"
George Oliver Smith
The search for a six-year-old boy with the educational development of a youth of about eighteen, informed through the services of an electromechanical device, would have fired public interest, Government intervention, and would also have justified Paul Brennan's depth of interest.
"The Fourth R"
George Oliver Smith