Data: MediumMedium quality — at least 60% of universal parameters and pins are present, but some key data is missing. Verify specific values against datasheets before critical use.
Similar-era DHT triode on UX4 base but with 5V/0.25A filament — not a drop-in due to different filament requirements
Electrical Specifications
Absolute Maximum
Anode Voltage (max)Max Plate Voltage90V
Typical Operating
Anode Voltage (typical)Plate Voltage90V
Grid 1 Bias VoltageGrid Voltage-4.5V
Anode CurrentPlate Current1.7mA
Notes
Originally issued as UV199 (UV prefix = bayonet base variant), redesignated UX199 in August 1925 when the UX4 pin base became standard. UV199 and UX199 are electrically identical but have different pin lengths.
Cunningham marketed the same tube as CX-299 (bayonet) and later C-299 (UX pins).
Thoriated tungsten filament — requires careful filament voltage regulation. Rated for 3.3V DC from dry cells; do not exceed rated voltage or filament life will be drastically shortened.
Designed for portability: the extremely low filament drain (60 mA) enabled receivers to run from small dry cells, making portable radios practical for the first time.
Production by RCA continued until 1931; after 1927 few new receivers were designed around this tube as newer types offered better performance.
Historical significance: one of the first tubes to enable truly portable battery-powered radio receivers, helping bring radio to rural areas without electricity.
Pin Layout — UX4
1Filament (f+)
2Plate
3Grid
4Filament (f-)
Socket-Compatible Tubes ⚠ Not electrically compatible