In 1919 the General Electric Company (Osram not GE USA) together with the Marcony company established the Marconi Osram Valve Company Ltd to bundle their strengths for the ever increasing demand for vacuum tubes or valves.
In 1937 Marconi Osram introduced their first Kinkless Tetrode the KT66. Kinkless is an attribute of this tube which indicates that the characteristic unwanted ‘kink’ in the anode current/voltage curve in a standard tetrode tube is suppressed. The Mullard/Philips had solved this problem by adding a third grid in their tubes tro surpress the secondary emission that causes this kink but Philips had this pentode tubedesign patented so the competion had to find another solution. The solution that was first found by two EMI engineers was to insert two beamforming plates that beams the electron stream from the cathode to the anode to reduce secondary emission significantly. Other benefits of this beaming tetrode were more power efficiency, less harmonic distortion and allowance for more powerful tubes like the American 6550 a classic example of a powerful beaming tetrode first introduced by Tung-Sol.
The first kinkless or beaming tetrode, the 6L6, was introduced in 1936 by RCA because Marconi Osram licensed their invention to RCA thinking it could not be massproduced. A costly mistake because the 6L6 has become one of the most succesful powertubes and can still be found nowadays in several guitar amplifiers.
KT66 by Genalex
One of the most known and praised series from Genalex/Marconi Osram is the ‘Gold Lion’ line-up. Most famous tube was the in 1957 introduced KT-88 the successor of the KT66 generating 100 Watts in a push-pull configuration where the KT66 produced only 50 Watts
Genalex Gold Lion KT88
The KT88 is very often copied by Chinese firms that do not implement the rigor quality of the original Genalex Gold Lion KT88’s or the new ones we sell.