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Radio-Frequency Vacuum Tube (EIMAC)


The instrument consists of two glass vacuum tubes in original protective wooden frames. The glass bulbs have ceramic bases with four metal connection prongs. There is a metal connection point just above the ceramic base of each of the glass bulbs. Inside the bulb, there are four metal cylinders arranged around a metal post. Under the cylinders is a concave metal disk. The center post sticks out of the top of the glass bulb. The tubes are supported by elasticized cotton bands in the protective frame.

Item a is secured in place by a piece of twine.
Item b is secured in place by a piece of cotton string.

Accession Number:

Alternative Name:

Primary Materials:

Wood, glass, ceramic, metal, cotton, twine


On ceramic part of item b, there is a white sticker marked with black ink, reading “JAN-CIM 304TH VT254 MADE In U.S.A.”

On the glass bulbs of both tubes is grey ink reading “EIMAC Reg. U.S. Pat. Off. 304TH/VT254 MADE IN U.S.A Des. Pat. No. 127753 Des. Pat. No. 136792”.

On the top of item b, there is a piece of tape marked in blue ink reading “unknown”.

Dimensions (cm): Length 23, Height = 38, Width = 8.5 cm


The vacuum tubes generate radio-frequency signals. They were used to drive a radio frequency gas discharge for studying spectroscopy. These tubes are unusually high-powered radio frequency tubes.


Both tubes and supportive frames are in very good condition. The elasticized cotton bands on both frames are brittle from age.

Associated Instruments:

Manufacturer: EIMAC

Date of Manufacture:


The item was acquired from, the University of Toronto Physics Department. The tubes were originally collected from faculty member Prof. Brian Stat.

Additional Information and References:

Historical Notes:

The tubes were most likely used for studies in spectroscopy by Prof. Bryan Statt at the University of Toronto.

  • Donated to UTSIC