In the

vacuum-tube radio The early history of radio is the history of technology that produces and uses radio instruments that use radio waves. Within the timeline of radio, many people contributed theory and inventions in what became radio. Radio development began as ...

, an electron-coupled oscillator or ECO oscillator uses a

screen-grid tube A tetrode is a vacuum tube (called ''valve'' in British English) having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids and a plate (called ''anode'' in British English). ...

with the cathode, control grid and screen grid forming the elements of the frequency-generating circuit while the plate is in the output circuit, shielded from the oscillator circuit proper by the screen grid. The ECO oscillator is practically impervious to rather drastic variations in its load circuit. The variation in the heater-cathode capacity with temperature changes tends to compensate for other capacity-temperature effects, with the result that the frequency creep during warming-up is less than is usual with the same tubes in more conventional circuits. The ECO oscillator was used for shortwave

superhet A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carri ...

radios.

References

Sources

* Electronic oscillators 1932 introductions {{Electronics-stub