CV138 / EF91

20.00 USD

12.00 USD Save 8.00 USD

Fine RF screened pentode tubes, 1950's production, manufactured for the British armed forces by renowned Mullard. These 7 pin miniature glass tubes have silver plates and top square getters. They are printed in white logos MULLARD B.V.A. EF91 BRITISH MADE, and on reverse side War Department arrow 6AM6 (typically LK), CV138 KB/D - indicating Mitcham factory.

Condition

New Bulk

	Tube Matching 6.00 USD by tube
LEARN MORE WHY ? 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. HOW ? 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.