[电] cavity-resonatior frequency meter

kōng qiāng xié zhèn qì pín lǜ jì ㄎㄨㄥ ㄑㄧㄤ ㄒㄧㄝˊ ㄓㄣˋ ㄑㄧˋ ㄆㄧㄣˊ lv4 ㄐㄧˋ