Its purpose in life was to be the local oscillator and mixer in AM radios, and a kazillion of them were made to fill that purpose.

它来是被用作调幅收音机中的混频管，并且被大量的生产出来以实现这个用途。

The maximum of B along elevation direction is closely under the central section of coil.The B of equiamplitude magnetic field is increased by increasing of the output current ...

等幅高频磁场的磁感应随高频电源输出电流的增加而增加,磁场调幅处理能高磁场内的磁感应,高调幅波信号的幅值电压,可有效高磁场内的磁感应。