• Ham radio operators, hobbyists, audio and broadcast enthusiasts and antique collectors enjoy buying, trading and building amplifiers and radios with vintage vacuum tubes. While the 4-1000 (4-1000A) vacuum tube, produced in the 1950s by Eimac/Eitel McCullough, Inc., is not currently being manufactured, there are online sites, like eBay, where you can buy or bid on them.
  
  

General Description

• The 4-1000A vacuum tube was a radial beam power tetrode--a vacuum tube with four elements, used as an amplifier, modulator or oscillator. Encased in a glass, the vacuum tube was 9.63 inches long, 5.25 inches in diameter and 1.5 lbs.
  
  

Electrical and Mechanical Specifications

• This vacuum tube had a thoriated tungsten filament, operated at 7.5 volts and had a current of 21 amperes. In addition, the DC (direct current) bias/grid voltage did not exceed 500 volts, the DC screen voltage did not exceed 1,000 volts and the plate supply voltage did not exceed 6,000 volts.
  
  Mounted vertically and positioned atop of a five-pin metal shell, the vacuum tube connected into a socket chassis; the specifications recommended the Eimac SK-500 Air System Socket. The base could be up or down (see Reference 2).
  
  

Cooling

• The V-1000 vacuum tube required forced air cooling to dissipate the heat and prevent damage to the tube. The base seal temperatures needed to stay below 150 degrees Celsius, or 302 degrees Fahrenheit, and the plate seal temperatures had to remain below 200 degrees Celsius, or 392 degrees Fahrenheit. The use of the Eimac SK-500 Air System Socket, with its SK-506 Air Chimney that controlled air flow around the tube, simplified the necessary cooling.