Not just a replacement, but an improvement!
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EML 300B
Last datasheet revision:
2009-September-16
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300B Filament Ratings
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| Filament Voltage |
5 Volt (AC or DC)
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| Tolerance on filament voltage |
4%
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| Filament Current |
1.3 Ampere
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300B Maximum Conditions
Not possible as operating point
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| Plate Voltage |
450Volt
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| Plate Current |
100mA
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| Plate Dissipation |
40Watt (note5)
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| Power Output in Class A |
14Watt
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| Grid resistor with Auto Bias |
250k Ohm (note4)
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| Grid resistor with Fixed Bias |
50k Ohm (note4)
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300B Factory Test conditions
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| Plate Voltage |
300V
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| Plate Dissipation |
17Watt
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| Plate Current |
56mA
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| Grid Voltage |
-58Volt
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| Plate Impedance |
700 Ohm
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| Amplification Factor |
3,9
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| Transconductance |
5.6 mA/V
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300B Typical Data
Recommended Operating point
SINGLE ENDED Operation, Class A1.
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| Plate Voltage |
350V
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| Plate Dissipation(at no signal) |
27Watt
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| Plate Current |
78mA
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| Grid Voltage |
-71Volt
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| Plate Impedance |
790 Ohm
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| Amplification Factor |
3,9
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| Transconductance |
5.6 mA/V
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| Tube Output Power |
8Watt @ 3k Ohm
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| Load Impedance (Ra) |
1600 - 4000 Ohm
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300B Typical Data
Recommended Operating point
PUSH-PULL Operation, Class A1.
ALL values are for both tubes together
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| Plate Voltage |
325V
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| Plate Dissipation(no signal) |
44Watt
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| Plate Dissipation(full signal) |
57Watt
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| Plate Current |
135mA
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| Grid Voltage |
-64,2Volt
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| Tubes Output Power |
16,5 Watt
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| Load Impedance (Raa) |
4000 Ohm
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300B Mechanical Data
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Size including Socket
(but excluding pins)
165 x 65 mm
6.5 x 2.6 Inch
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Single Tube weight
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145 Grams
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Shipment weight for
pair in gift box
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840 Grams
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- Note 1) Hard-metals can be used in electron tubes, though these are more difficult to use, and more costly than the classical nickel. Hard metal plates have a more precise plate distance, and do not change shape when heated, or at mechanical shock. This ensures reproducible tube parameters, and long term stability. Wolfram grids allow the most precise grid wire distance, because wolfram is an extreme hard metal. Best grid geometry ensures uniformity and linearity of the tube curves.
- Note 2) Individual Test data, such as: Matching Data, Grid Current, Vacuum, Filament Current, etc., are on the Certificate that is on the outside of the tube box. Each tube is numbered from the inside, with a metal Tag
- Note 3) Plate Curves: Made with the Sofia Digital Curve tracer. Plate curves with courtesy of AMR
- Note 4) We recommend the same values as Western Electric in their 1950 Datasheet.
- Note 5) The Western Electric 1950 Datasheet says 36 Watt maximum dissipation. Later datasheets say 40 Watt. Though 40 Watt is possible, this is a peak value only, and no normal working point. When you intent to get the "maximum" out of a 300B, and operate this tube at the limits of safe operation, it is a better idea to use the 300B-XLS in such a case.
- Note 6. Some manufacturers claim to be the only one with a center tapped filament, but this is not longer true. At EML we build since several years now all triodes center tapped, not only the the 300B.
- Note 7) Don't experiment with lower filament voltage, and expect better lifetime. If it was that easy, we would make them like this ourself. The specified filament voltage is the one for best lifetime.
- Note 8) Gold plated grids have a few advantages. Amongst other this will give better bias stability of the tube, some protection against accidental overload, and better linearity of tube curves.
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