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Power - Beam (NOT sweep) ·BeamPower

3D21A

CBS-Hytron 3D21A high-vacuum blocking-oscillator and pulse-modulator tube with 6.3/12.6 V series-parallel heater, 3500 V plate rating and 7–21 kW typical pulse output.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
-
Base pins
8
Nominal heater
12.6 V / 850 mA

Description

Beam tetrode for blocking oscillator, pulse modulator, deflection amplifier, regulator, and series-valve service.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
-
Base pins
8
Nominal heater voltage
12.6 V
Nominal heater current
850 mA
Parallel heater voltage
6.3 V
Parallel heater current
1.7 A
Series capable
Yes

Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Beam Power

X-ray radiationInterelectrode capacitances
Transconductance
0.00055 S
Max plate voltage
3500 V
Max screen voltage
850 V
Max plate dissipation
15 W
Max screen dissipation
3 W
Max grid dissipation
0.5 W

CBS-Hytron 1957: maximum plate 3500 V (5000 V transient peak), grid2 850 V, grid1 instantaneous -500 to +220 V, plate dissipation 15 W, grid2 dissipation 3 W, grid1 dissipation 0.5 W. At Va 600 V, Vg2 300 V, Vg1 -30 V, Ia 30 mA, Ig2 2.5 mA: gm 550 µmhos = 0.00055 A/V. Peak heater-cathode 150 V; cathode preheat >=30 s. Pulse operation Va 3500/2500/1500 V, Vg2 800 V, Vg1 -150 V, load 450/305/160 Ω, output 21/14/7 kW. Pulse nominal 10 µs and <=12 µs total per 240 µs. Conditional 4500 V DC plate possible with Vg2 <=400 V, resistive load and no transients. Beam construction unverified; existing classification retained.

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

1958 Brimar Radio Valve No 7

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Application

  • Application

    Blocking oscillator / pulse modulator

Other

  • Pulse length maximum

    10 us

    Pulse

  • Peak pulse power output

    21 kW

    Pulse

Data set 02

1960 CBS Hytron

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

  • Pulse Power

    20000 W

    PulseModulator