3HK5

Sylvania 3HK5 gain-controlled VHF amplifier triode with 2.9 V 450 mA heater, high 15 mA/V transconductance and 7GM miniature seven-pin base.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 7GM
Socket code: -
Base pins: 7
Nominal heater: 2.9 V / 450 mA

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 7GM
Socket code: -
Base pins: 7
Nominal heater voltage: 2.9 V
Nominal heater current: 450 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

7GM - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN1G1	A	G1 — Control Grid EIA transcription; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 7GM
PIN2K	A	K — Cathode EIA transcription; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 7GM
PIN3H	—	H — Heater EIA transcription; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 7GM
PIN4H	—	H — Heater EIA transcription; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 7GM
PIN5P	A	P — Plate (Anode) EIA transcription; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 7GM
PIN6IS	A	IS — Internal Screen EIA transcription; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 7GM
PIN7K	A	K — Cathode EIA transcription; independent manufacturer confirmation pending	Unverified EIA Base Connections, printed page 129, 7GM

Section ratings

1 physical section, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 5000 Ω
Transconductance: 0.015 S
Amplification factor: 75
Max plate voltage: 200 V
Max plate dissipation: 2.3 W
Max cathode current: 22 mA

Sylvania Technical Manual 1970 pp248–249: 3HK5 gain-controlled VHF triode, E7-1 seven-pin miniature 7GM base, 2.9 V 0.45 A heater with 11 s warm-up. Design maximum plate 200 V, plate dissipation 2.3 W, DC cathode current 22 mA, negative grid voltage magnitude 50 V, maximum heater-cathode voltage ±100 V, self-bias grid-circuit resistance 1 MΩ. Warning: control grid-cathode spacing very small; commercial tube testers should not apply more than 30 V DC or peak AC between grid and cathode, especially under mechanical excitation. Typical Class A1 at Va 135 V, Vg -1 V: Ia 12.5 mA, gm 15000 µmhos (0.015 A/V), mu 75, rp approximately 5000 Ω. Grid voltage for gm 150 µmhos approx -5 V, for gm 1500 µmhos approx -2.6 V. Shielded direct capacitances Cgp 0.29 pF, input 4.4 pF, output 2.6 pF, heater-cathode 2.5 pF. At 200 MHz, input resistance 600 Ω and input capacitance 9.0 pF measured grounded-plate; noise figure 4.2 dB in optimized neutralized noise-matched triode RF amplifier. These 200 MHz figures are operating/measurement-dependent and not interchangeable with direct capacitances.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

1970 Sylvania Technical Manual

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate Voltage
135 V
Grid Voltage
-1 V
Plate Current
12.5 mA
Grid To Plate Capacitance
0.29 pF
Input Capacitance
4.4 pF
Output Capacitance
2.6 pF