
Radio tubes (electrovacuum devices). What is this?
The radio lamp is an electronic vacuum device that uses the principle of acceleration/deceleration of electrons in a vacuum (in a space that does not have air or space filled with an inert gas).
At the beginning of the last century, vacuum electric lamps were used in almost all radio electrical appliances. They can be in different shell: glass, silver. Any such device has in its composition some amount of precious metals: gold, platinum, palladium. These metals cover the tube grid (for incandescence), anodes, and cathodes.
They called this EVD so, thanks to some similarity to the usual light bulb we know. Electrovacuum lamp differs in its purpose and functionality.

Application
Today diodes and transistors are used in radio electronics circuits. Even microwave ovens and tube amplifiers can contain such lamps to radiate high frequencies.
According to the purpose of the EVD, they are classified into:
- Generator EVD
- Convertive EVD
- Amplifying EVD
- Indicator EVD
- Modulating Evolution
- Rectifying EVD
- Measuring EVD
On a working mode:
- Continuous
- Pulse
- Ultra-high frequency
- High-frequency
- Low-frequency
Some types of electrovacuum products:
- ГУ-34Б-1, ГУ-43А, ГУ-70Б, ГУ-71Б, ГУ-72, ГУ-73Б (П), ГУ-74Б, ГУ-78Б, ГУ-84Б;
- ГМИ-2Б, ГМИ-4Б, ГМИ-5, ГМИ-6, ГМИ-7 (7-1), ГМИ-10, ГМИ-11, ГМИ-14Б, ГМИ-19Б, ГМИ-21-1, ГМИ-24Б, ГМИ-26Б, ГМИ-27А (Б);
- ГМИ-32Б (Б1), ГМИ-42Б, ГМИ-83 (Б), ГМИ-89, ГМИ-90;
- ГС-23Б, ГС-36Б.