Voltage Tetrode ·Tetrode
Directly heated tetrode with a heavy five-volt filament. Available source material confirms tetrode construction but does not establish a narrower functional application confidently.
4A137B Tetrode. Technical characteristics, ratings, and operating information are provided in the approved Standard Valves datasheet.
European 5-pin base
General specifications
Properties common to every published source and operating point.
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
1 physical section, each with unique specifications.
Section 1
Standard Telephone and Cables 4A/137B directly heated coplanar-grid tetrode, oxide-coated 5 V 1.6 A filament and British five-pin base. Manufacturer typical rating at anode 145 V and coplanar grid conditions: amplification factor 5.3 and internal anode impedance about 3600 ohms; values vary with published power-stage operating points. Maximum DC anode voltage 250 V and maximum DC anode current 45 mA. Maximum potential difference between screen and control grids 150 V (NOT unrestricted maximum screen-to-cathode voltage); maximum positive control-grid swing +10 V. Typical screen/positive-grid potentials and RF power output depend on operating mode. Vertical mounting recommended; horizontal mounting requires filament plane vertical. Interelectrode capacitances grid-anode 38 pF, input 18 pF and output 9.4 pF.
Source-dependent data
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.
Data set 01
Published operating points and test conditions from this source.
Voltage
5 v
Nominal curren
1.6 A
Grid to anode
38 pF
Inpu
18 pF
Outpu
9.4 pF
Maximum direct anode curren
45 mA
screen and control grids
150 v
positive swing of input voltage
10 v
February 1946
4 A
February 1946
4 A
FILAMENT VOLTAGE =
5 VOLTS
SCREEN VOLTAGE =
70 VOLTS
February 1946
4 A
February 1946
4 A
Va 145V Vg,
70 V