General Electric (GE)

EC90 / 6C4

13.00 USD

Fine triode amplifier tubes manufactured in the United States for electronics giant Hewlett-Packard by renowned General Electric. These double tested 7 pin miniature glass tubes, designed as high frequency oscillators for premium electronic equipment, come with gray plates, top getters, and are printed in whbite with HP logo, MADE BY GENERAL ELECTRIC, with Owensboro Kentucky 188-5 code, 68-09 indicating 1968 production. They are glass etched 6C4 U.S.A. with dot code, and boxed in standard HP white tubes printed PART NO . 1921-0005 6C4.


Tube Matching
Tube Matching
6.00 USD by tube


A tube may have one, two, or three internal sections depending on the purpose of the tube; somtimes these sections are all the same, sometimes they are different. Due to manufacturing and material tolerances, there may be slight differences between the original specification and the actual tube. Tube matching tests each one of these internal sections and selects tubes, compared to original specifications at manufacture, for balanced performance and good sound.


All our tubes are tested by us prior to packing on our Stark, AVO, Simpson or RF Laboratories Inc. calibrated testers. On request for tube matching, tubes are matched for Mutual Conductance in Micromhos and Plate Current in Milliamps on our Amplitrex or Radioelec Duovac testers, with results printed for each  individual tube. Certain tubes difficult to test are matched for Mutual Conductance in Micromhos only on one of our regular calibrated testers. On request we can also test for Microphonics.


9 Items

Data sheet

7 pin miniature B7G
Boite type
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