Loewe 2HF
DC Dual Space Charge Tetrode
1926 (German)

The 2HF was a complete 2 stage amplifier which included the required 2 resistors and 1 capacitor inside the bulb. These components were sealed in their own small glass bulbs to prevent outgassing. The early Loewe multi-section tubes are considered by some to be the first "integrated circuits".