1625

Beam Tetrode — UX7

Tung-Sol

Known Equivalents & Substitutes

CV659VT136

Similar Tubes (Not Drop-In Compatible)

Same electrical characteristics but 6.3V/0.9A heater on UX5 base — different base and heater voltage, not pin-compatible

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Plate Voltage (max)750V

Screen Voltage (max)Screen Voltage (max)350V

Anode Dissipation (max)Plate Dissipation (max)30W

Screen Dissipation (max)Screen Dissipation (max)3.5W

Max Grid ResistorGrid Resistor (max, RF Class C)10,000MΩ

Typical Operating

Anode Voltage (typical)Plate Voltage (typical, RF Class C)600V

Screen Voltage (typical)Screen Voltage (typical, RF Class C)200V

Grid 1 Bias VoltageGrid Voltage (typical, RF Class C AM)-90V

Anode CurrentPlate Current (typical, RF Class C)100mA

Screen CurrentScreen Current (typical, RF Class C)

Output

Output PowerPower Output (RF Class C, CW)50W

Capacitances

Grid-to-Plate CapacitanceGrid to Plate Capacitance (max)0.2pF

Grid-to-Cathode CapacitanceControl Grid to Cathode Capacitance11pF

Anode-to-Cathode CapacitancePlate to Cathode Capacitance7pF

Heater

Heater VoltageHeater Voltage12.6V

Heater CurrentHeater Current0.45A

Notes

The 1625 is the 12.6V heater military version of the 807. Electrically identical except for heater voltage and base type.
Uses a 7-pin UX7 base with a top-cap plate connection. The 807 uses a 5-pin UX5 base — the two are NOT interchangeable without an adapter.
TDSL and ARRL references list RF Class C, Class B, and AB1 operating conditions. Primary use was in military AN/ARC-5 command set transmitters.
Widely available as war surplus; commonly adapted for amateur radio transmitter use at 12.6V mobile supply.
Datasheet capacitances measured with external shield: Cgk=11pF, Cak=7pF, Cgp=0.2pF.

Pin Layout — UX7

1Control Grid (g1)

2No Connection

3Heater

References

10mA

Heater

5Cathode

6Screen Grid (g2)

7No Connection

TCTop Cap —Plate (top cap)