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Russian 6C33C and 6C18C

Russian 6C33C and 6C18P



In 1976 a Mig 25 fighter jet landed in Hokkaido in Japan, it was flown by a soviet military pilot that wanted to defect to the west. This was a real field day for western miltary people as not so much was known about the MIG 25 and the plane was completely dismantled.

Two things startled the military analysts in the west, the first was that the plane was built using a lot of high tension steel, it was earlier thought that the MIG 25 was built in Titanium to withstand the heat that is generated by flying at mach 3 that the plane was capable of, that it was built in steel made it heavy so the performance was actually less than expected.

The second thing that surprised people in the west was that electronic tubes was used in some parts of the radio equipment. After a while it was understood that the tubes where used so the plane should be able to withstand EMP. An EMP, (Electro Magnetic Pulse) is generated by the detonation of a large nuclear bomb in the atmosphere, the electric field so generated destroys most solid state electronics and EMP is thought to be used as a possible electronic warfare measure.

In the power supply of the main radio unit of the MIG 25 a previously unknown triode tube was used, the Soviet military designation was 6C33C and it was a voltage regulator triode. The data of this tube was much better than anything made before in the west and SanEi of Japan imported some 6C33C tubes for audio application in 1997, renaming them EC33C for the Japanese consumer. Mr. Dakesue in Japan was the first person to design a 6C33C-B OTL power amplifier circuits in 1977.

The main characteristics of the 6C33C is that it has very high transconductance, high current capability and low internal resistance and also as the tubes where intended for use in miltary aircraft they are mechanically very robust. The nearest western equivalent is 6336 but data of 6C33C is better. 

6C18P younger sister of 6C33C