М
https://en.wikipedia.org/wiki/Closed-circuit_radio
the antenna circuit and the closed circuit must be tuned to the incoming high frequency, and the coupling between the antenna circuit and the closed circuit should ordinarily be made loose
Size: a a a
М
М
VB
S
З
ЕА
З
ЕА
VB
ЕА
ЕА
VB
ЕА
VB
ЕА
VB
ЕА
VB
ЕА