Voltage - Pentode or Tetrode (under 100V) vacuum tubes

Tetrode

Early directly heated Philips high-vacuum tetrode for battery receivers, designed for low-voltage detector and amplifier service with economical filament operation.

Base

Philips 4-pin

Socket

Not recorded

Heater

1.85 V

Sections

1

Tetrode

Directly heated double-grid tetrode for detection, RF and LF amplification, and output service at unusually low anode voltage, using space-charge-grid operation for battery receivers.

Base

A

Socket

Not recorded

Heater

3 V

Sections

1

Tetrode

Directly heated double-grid tetrode for detection, RF and LF amplification, and output service at very low anode voltage, suited to economical battery receivers.

Base

A

Socket

Not recorded

Heater

3.7 V

Sections

1

Pentode

Directly heated Raytheon subminiature pentode for low-power amplifier service in portable and wearable equipment. Its tiny filament demand and compact construction target battery-operated personal electronics.

Base

Not recorded

Socket

Not recorded

Heater

1.25 V

Sections

1

Tetrode-Tetrode

Directly heated subminiature double space-charge tetrode designed for cascaded audio-frequency voltage-amplifier service.

Base

7D

Socket

Not recorded

Heater

0.625 V

Sections

2

Pentode

Extremely low-drain directly heated subminiature pentode for audio-frequency and direct-coupled amplification from very low battery supplies.

Base

5J

Socket

Not recorded

Heater

0.625 V

Sections

1

Pentode

Ultra-low-drain directly heated subminiature pentode for portable and wearable voltage amplification, using only a 0.625 V, 15 mA filament.

Base

5J

Socket

Not recorded

Heater

0.625 V

Sections

1

Pentode

Pentode intended for voltage-amplifier or receiving service; available source does not clearly establish a narrower functional classification.

Base

Not recorded

Socket

Not recorded

Heater

1.25 V

Sections

1

Tetrode-Tetrode

Directly heated subminiature twin tetrode designed for electrometer service, with extremely low nominal control-grid current for precision measurement.

Base

8CC

Socket

Not recorded

Heater

1.25 V

Sections

2

Pentode

Subminiature directly heated electrometer pentode designed for measurement of extremely small currents, with exceptionally low control-grid current.

Base

5C

Socket

Not recorded

Heater

1.25 V

Sections

1

Pentode

Subminiature directly heated electrometer pentode designed for measurement of extremely small currents, with exceptionally low control-grid current.

Base

4G

Socket

Not recorded

Heater

1.25 V

Sections

1

Pentode

Directly heated subminiature pentode designed specifically for low-power radiosonde electronic service.

Base

8YA

Socket

Not recorded

Heater

1.4 V

Sections

1

Pentode-Pentode

Subminiature directly heated twin pentode intended for RF amplifier service, combining two compact pentode systems for high-frequency equipment.

Base

8CD

Socket

Not recorded

Heater

1.25 V

Sections

2

Pentode

Pentode designed for radio-frequency or wide-band amplifier service in receiving or electronic equipment.

Base

5A

Socket

Not recorded

Heater

1.25 V

Sections

1

Heptode

Low-consumption battery heptode for oscillator and frequency-converter service in portable superheterodyne receivers. Its economical directly heated filament minimizes battery drain while providing useful conversion performance.

Base

Not recorded

Socket

Not recorded

Heater

1.4 V

Sections

1

Diode-Pentode

Receiving diode-pentode intended for radio IF amplification, detection, and control functions, with the pentode providing gain and the diode furnishing signal rectification.

Base

Not recorded

Socket

Not recorded

Heater

1.4 V

Sections

2

Pentode

Service designation explicitly associated with the 1T4 variable-mu miniature battery RF pentode. It provides controlled RF/IF gain using a low-power directly heated filament suitable for portable equipment.

Base

Not recorded

Socket

Not recorded

Heater

1.4 V

Sections

1

Diode-Pentode

Directly heated battery diode-pentode combining signal detection with low-frequency voltage amplification. Its 1.4 V, 50 mA filament suits portable receivers while the pentode provides useful gain following the detector stage.

Base

Not recorded

Socket

Not recorded

Heater

1.4 V

Sections

2

Diode-Pentode

Subminiature directly heated diode-pentode for battery equipment, combining a detector diode with an audio-frequency pentode. Its exceptionally economical 1.25 V, 25 mA filament suits compact low-power portable electronics.

Base

Not recorded

Socket

WIRE8

Heater

1.25 V

Sections

2

Diode-Pentode

Directly heated battery diode-pentode, equivalent to 1S5, combining signal detection with audio preamplification. Its low-consumption 1.4 V, 50 mA filament and high-resistance pentode suit portable radio receivers.

Base

B7G

Socket

B7G

Heater

1.4 V

Sections

2

Diode-Pentode

Battery-operated diode-pentode combining a detector diode with a low-frequency amplifier pentode. Its 1.2 V, 60 mA directly heated filament and low operating currents suit economical portable receiver service.

Base

Not recorded

Socket

Not recorded

Heater

1.2 V

Sections

2

Pentode

Subminiature low-frequency pentode designed for hearing aids and other very-low-power battery-operated equipment.

Base

Not recorded

Socket

Not recorded

Heater

0.625 V

Sections

1

Pentode

Pentode designed for radio-frequency or wide-band amplifier service in receiving or electronic equipment.

Base

Not recorded

Socket

B7G

Heater

1.4 V

Sections

1

Pentode

Mullard subminiature sharp-cutoff RF pentode for battery-operated equipment, also usable as a frequency changer. Its compact directly heated construction supports both high-frequency amplification and conversion in portable receivers.

Base

Not recorded

Socket

WIRE8

Heater

1.25 V

Sections

1

Pentode

Subminiature battery RF pentode for amplification and frequency-changer service. Its 1.25 V, 25 mA filament and very high plate resistance provide useful signal gain and converter operation with exceptionally low filament consumption.

Base

Not recorded

Socket

WIRE8

Heater

1.25 V

Sections

1

Pentode

Mullard subminiature sharp-cutoff RF pentode for battery equipment and frequency-changer service. Manufacturer data document both RF amplification and conversion operation from low-voltage battery supplies.

Base

SUBMINIATURE

Socket

WIRE8

Heater

1.25 V

Sections

1

Pentode

Mullard subminiature variable-mu RF pentode for battery-operated equipment. It combines compact construction, low-power filament operation, and controlled gain for portable receiver RF stages.

Base

Not recorded

Socket

WIRE8

Heater

1.25 V

Sections

1

Pentode

Mullard subminiature AF voltage-amplifying pentode designed for hearing aids and extremely low-power battery operation. Its directly heated miniature construction minimizes heater demand for compact portable audio equipment.

Base

SUBMINIATURE

Socket

WIRE8

Heater

0.625 V

Sections

1

Pentode

Low-power directly heated subminiature AF pentode for hearing aids. Philips documentation places it in very-low-current battery audio service, closely related to the DF67 family and optimized for compact portable amplification.

Base

SUBMINIATURE

Socket

WIRE8

Heater

0.625 V

Sections

1

Pentode

Mullard subminiature AF voltage-amplifying pentode for hearing aids and low-current battery service. Its directly heated construction provides small-signal audio gain while keeping filament consumption suitable for miniature portable equipment.

Base

SUBMINIATURE

Socket

WIRE8

Heater

0.625 V

Sections

1

Pentode

Subminiature pentode designed for RF and IF amplifier service, described as similar to type 5678. Its compact construction suits high-frequency small-signal stages in miniature receiving equipment.

Base

Not recorded

Socket

WIRE8

Heater

1.25 V

Sections

1

Pentode

Subminiature low-frequency pentode for hearing aids and other very-low-power battery equipment. Its directly heated construction targets compact audio voltage amplification where minimal filament consumption is essential.

Base

SUBMINIATURE

Socket

WIRE8

Heater

0.625 V

Sections

1

Pentode

Directly heated Mullard subminiature AF voltage-amplifying pentode for hearing aids. Its 0.625 V, 25 mA filament is specifically suited to extremely low-power battery-operated audio equipment.

Base

Not recorded

Socket

WIRE8

Heater

0.625 V

Sections

1

Pentode

Telefunken directly heated subminiature electrometer pentode designed for circuits measuring extremely small grid currents. Its defining role is ultra-high-impedance instrumentation rather than conventional audio or RF amplification.

Base

Not recorded

Socket

WIRE8

Heater

1.25 V

Sections

1

Pentode

Subminiature variable-mu RF pentode designed for battery operation. Its compact directly heated construction and extended-control characteristic support automatic gain-regulated high-frequency amplification in portable equipment.

Base

Not recorded

Socket

WIRE8

Heater

1.25 V

Sections

1

Pentode

Equivalent designation printed with the 1T4 directly heated variable-mu RF/IF pentode. It provides controlled high-frequency gain while using a low-power filament suited to battery-operated receivers.

Base

B7G

Socket

B7G

Heater

1.4 V

Sections

1

Pentode

Battery pentode designed for high-frequency amplification. Its low-power construction supports RF signal stages in portable battery-operated equipment where heater consumption must be minimized.

Base

Not recorded

Socket

Not recorded

Heater

1.2 V

Sections

1

Heptode

Low-consumption battery heptode frequency converter for portable superheterodyne receivers, using a 1.4 V filament for economical oscillator-mixer operation.

Base

Not recorded

Socket

Not recorded

Heater

1.4 V

Sections

1

Heptode

Directly heated battery heptode designed as the oscillator-mixer frequency changer in portable superheterodyne receivers. Its low filament consumption and modest electrode currents reflect economical battery-powered radio service.

Base

Not recorded

Socket

IO

Heater

1.4 V

Sections

1

Heptode

Directly heated battery heptode for oscillator-mixer frequency conversion in portable superheterodyne receivers. Its 1.4 V, 50 mA filament provides useful receiver conversion performance with very low filament power consumption.

Base

B7G

Socket

B7G

Heater

1.4 V

Sections

1

Heptode

Very low-consumption battery heptode for oscillator-mixer frequency conversion in portable radios. Its 1.4 V, 25 mA filament is specifically suited to receivers where extending battery life is important.

Base

B7G

Socket

B7G

Heater

1.4 V

Sections

1

Heptode

Battery heptode frequency converter for portable radio receivers, combining oscillator and mixer action with a directly heated 1.2 V low-current filament.

Base

Not recorded

Socket

Not recorded

Heater

1.2 V

Sections

1

Pentode

RFT pentode documented with nominal values, operating characteristics, and maximum ratings. The available manufacturer material does not provide sufficiently explicit application wording to justify a narrower functional classification.

Base

Not recorded

Socket

WIRE8

Heater

1.2 V

Sections

1

Diode-Tetrode

Early Philips binode combining diode detection with high-gain tetrode amplification for radio receiver signal processing, using a 4 V heater characteristic of prewar European equipment.

Base

Not recorded

Socket

B5

Heater

4 V

Sections

2

Tetrode-Tetrode

Directly heated dual space-charge-grid electrometer tetrode designed for measuring extremely small currents and voltages, with exceptionally low grid reverse current.

Base

Not recorded

Socket

B9A

Heater

1.25 V

Sections

2

Pentode

Subminiature wire-ended pentode designed specifically for electrometer applications. Its construction targets extremely sensitive, high-impedance measurement circuitry where very small currents must be amplified without excessive loading.

Base

Not recorded

Socket

Not recorded

Heater

1.25 V

Sections

1

Pentode

Very-low-power directly heated electrometer pentode designed for linear or logarithmic preamplifier measurement circuits. Its defining function is amplification of extremely small measurement signals in high-impedance instrumentation.

Base

Not recorded

Socket

Not recorded

Heater

1.25 V

Sections

1

Diode-Pentode

Diode variable-mu pentode for RF, IF, and audio-frequency amplification together with signal detection. The pentode provides controlled gain for AVC while the diode supplies the associated detector function.

Base

NOVAL

Socket

B9A

Heater

6.3 V

Sections

2