attenuator
audio-frequency tube
ballast regulator
ballast tube
beam-switching tube
convertor
current regulator
damper
detector
discriminator
doubler
ear trumpet
electronic hearing aid
focus tube
generator
hard-of-hearing aid
hearing aid
iconoscope
inverter
limiter
local-oscillator tube
megaphone
mixer tube
modulator
multiplier
multipurpose tube
multivibrator
oscillator
output tube
phase inverter
picture tube
power tube
preamp
preamplifier
pulse generator
radio-frequency tube
receiving tube
rectifier tube
regulator
repeater
speaking trumpet
stethoscope
transducer
transistor hearing aid
trigger tube
vacuum-tube hearing aid
electronic equipment
audio amplifier
booster
booster amplifier
booster station
maser
relay link
relay station
relay transmitter
analyzer
antenna
circuit
circuitry
controller
converter
filter
frequency
input
interface
measurement
microphone
module
processor
receiver
recorder
resistor
transformer
transistor
transmitter