[电] lumped-constant-tuned heterodyne-frequency meter

jí zǒng cháng shù tiáo xié wài chà pín lǜ jì ㄐㄧˊ ㄗㄨㄥˇ ㄔㄤˊ ㄕㄨˋ ㄊㄧㄠˊ ㄒㄧㄝˊ ㄨㄞˋ ㄔㄚˋ ㄆㄧㄣˊ lv4 ㄐㄧˋ