300B
Valve, Western Electric, 1938
A directly heated power triode introduced by Western Electric in 1938, rated for about 10 watts or less at low plate voltages and still made to its original specification.
A-01, isometric, same camera for both
- Drawing
- A-01
- Introduced
- 1938
- Produced
- 1938 onward, with a break before a restart in 1996; current production at the Rossville Works, Georgia
- Made in
- United States
- Designed by
- Not credited by sources
- Launch price
- Not confirmed
- Size
- 62 x 165 x 62 mm
- Weight
- Not published
Western Electric released the 300B in 1938 as a moderate-power filamentary triode for Class A audio service, and the 1939 data sheet credits Bell Telephone Laboratories research. It was used in the company's cinema sound systems, including Wide Range and Mirrophonic. It differs from the earlier 300A only in the position of the bayonet pin on the base. Western Electric re-established tube manufacturing in 1996 and now builds the 300B at the Rossville Works in Georgia.
Specification
| Item | As published |
|---|---|
| Filament | 5.0 volts AC or DC, 1.2 amperes nominal |
| Plate voltage | 300 volts typical test; 450 volts maximum |
| Plate dissipation | 40 watts maximum |
| Amplification factor | 3.85 |
| Plate resistance | 700 ohms |
| Transconductance | 5500 micromhos |
| Power output example | 6.6 watts at 300 volts, 60 mA, 2400 ohm load |
| Base | Medium four-pin thrust type |
Still in production
Western Electric 300B
Western Electric still makes it.
The house
- Founded
- 1869
- Founder
- Enos M. Barton and Elisha Gray
- Origin
- Chicago, Illinois, United States
- Today
- The original company ended in 1995, and Western Electric Export Corporation, a privately owned audio company in Rossville, Georgia, holds the trademark and makes the 300B.
Sources
- https://worldradiohistory.com/Archive-Catalogs/Suppliers/VWXYZ/Western-Electric-Vacuum-Tube-Data-300A--300B-7-pages.pdf
- https://www.westernelectric.com/300b
- https://audioxpress.com/article/r-d-stories-the-original-western-electric-300b-vacuum-tube-now-shipping-worldwide
- https://en.wikipedia.org/wiki/300B
Notes for the record: Electrical values are from Western Electric V.T. Data Sheet 300A and 300B, Issue 1, copyright 1939, read as page images. Dimensions are the sheet's 6 1/2 in maximum overall length and 2 7/16 in maximum diameter converted at 25.4 mm per inch; the tube is round, so depth equals width. The sheet credits Developments of Bell Telephone Laboratories; no individual designer is named. Wikipedia lists 40 W thermal dissipation and about 16 cm by 6.1 cm; one search summary quoted 36 W from a tube database, which was not opened. Production history is from audioXpress, which says the Kansas City works finished its move in 1970 and Whitener re-established manufacturing there in 1996, with the Rossville Works established in 2018 and first batches shipped between October 2020 and January 2021. No launch price or weight was found.