Not just a replacement, but an improvement!

EML 300B

Last datasheet revision:
2008-March-20


Description

With this tube we have  taken the legendary 300B in production.  All critical parts, like grids and plates are constructed of hard metal for higher reliability and reproducible quality.  This tube is a direct replacement for the WE300B, and features a center tapped filament as well. (See Note6)

Features

  • Gold plated Grid
  • Center tapped filament
  • 4 circular cooling plates 
  • Hard metal Construction (Note1)
  • Two extra large getters
  • Hand blown Glass bulb
  • Anti-microphonic plate- and grid  suspension
  • These tubes are shipped in a high quality dual box
  • Tube printing with real gold (metal),  red color is glass burned into the glass 
  • Machined, solid tube base pins for highest contact precision. YAMAMOTO tube sockets highly recommended. 
  • Gold plated pins,  black ceramic socket.  (White bottom.)

  300B 

Detailed image
Curves
  .
300B Filament Ratings
Filament Voltage 
5 Volt (AC or DC) 
Tolerance on filament voltage
4%
Filament Current 
1.3 Ampere 
  .
300B Maximum Conditions
 
Not possible as operating point
Plate Voltage 
450Volt 
Plate Current 
100mA 
Plate Dissipation 
40Watt (note5)
Power Output in Class A 

14Watt 

Grid resistor with Auto Bias
250k Ohm (note4)
Grid resistor with Fixed Bias
50k Ohm (note4)
  .

300B Factory Test conditions

Plate Voltage 
300V 
Plate Dissipation 
17Watt 
Plate Current 
56mA 
Grid Voltage 
-58Volt 
Plate Impedance 
700 Ohm 
Amplification Factor 
3,9 
Transconductance 
5.6 mA/V 
.
  .

300B Typical Data
Recommended Operating point
SINGLE ENDED Operation, Class A1.

Plate Voltage 
350V 
Plate Dissipation (at no signal)
27Watt 
Plate Current 
78mA 
Grid Voltage 
-71Volt 
Plate Impedance 
790 Ohm 
Amplification Factor 
3,9 
Transconductance 
5.6 mA/V 
Tube Output Power
8Watt @ 3k Ohm
Load Impedance (Ra)
1600 - 4000 Ohm 
  .

300B Typical Data
Recommended Operating point
PUSH-PULL Operation, Class A1.
ALL values are for
both tubes together

Plate Voltage 
325V 
Plate Dissipation (no signal)
44Watt
Plate Dissipation (full signal)
57Watt
Plate Current 
135mA 
Grid Voltage 
-64,2Volt 
Tubes Output Power
16,5 Watt
Load Impedance  (Raa)
4000 Ohm 
  .
300B Mechanical Data

165 x 65 mm * 
6.5 x 2.6 Inch * 

* Length is including socket 
ceramic,  but excluding pins 

Tube weight
145Grams 
Shipped weight 
for double box
840Grams 
  .
  • Note 1)  Hard-metal filaments prevent filament breakage with DHT Tubes.  This material has a higher melting point than the classical nickel wires. Hard metal plates have a more precise plate distance, and do not change shape when heated.  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.   This ensures better uniformity and linearity at the low end of the tube curves.
  • Note 2)  Individual Test data, such as:  Matching Data, Grid Current, Vacuum, Filament Current, etc.,  are on the Certificate that comes with each individual Tube.  Each tube has  is numbered, inside the bulb  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 only one for best lifetime. Deviations in either direction will reduce tube lifetime significantly.

Subscribe or unsubscribe our Mailing List
© Emission Labs. All Rights Reserved.