[Amps] RE : Interesting Item...........................

[Peter Chadwick]

That style amplifer was designed at Moarconi in the late 1950's/early 1960s as part of the MST (Marconi Self Tuning ) range. There was a 1kW HF version with 16 4CX250Bs in two push pull distibuted amplifers running with 1100 volts on the plates: another 4 tubes were used as a driver. It went ot 27.5MHz, and ha an interesting  resoance at 28.5 which would lead to smoke....... A 500 watt version used in naval vessels (NT204) used 6 4CX250B in each side, and covered 240kHz to 24MHz. The 4CX250Bs were selected for some parameter which I can't remember: I know that the M-O Valve company and STC (ITT) never succesfully managed to duplicate the required characteristics - at least, at acceptable cost.
Good descriptions of these (and a mumber of other interesting HF equipments) are in the Proceedings of the IEE Convention on HF Commuincation of March 1963.

A quite good description of distributed amplifiers is in Millman and Taub, 'Pulse, Digital and Switching Waveform', 1965 edition. That even includes descriptions of Phantastrons!

Jos asked:> Could Marconie have been a member of the Philips group,<
No. Marconis was originally Marconi's Wirelss Telegraph and SIgnal Company Ltd, and became Marconi's Wireless Telegraph Company in about 1910. Known as MWT. It was bought by English Electric shortly after WW2 (English Electric had been formed in 1915 by taking over various German owned companies in the UK), and English Electric got bought the the UKs General Electric Company (GEC) in 1973 or so. GEC was wide ranging, from semiconductors to power stations to telecomms systems to various components (including transmitting, receiving and CR  tubes), industrial weighing machines, kitchen furniture, washing machines, cookers, refrigerators, petrol pumps, TV, military etc etc. It was split  up from 1994, all the bits sold off, the telecom stuff kept on and renamed Marconi, and the cash invested in buying telecom companies just before the market crashed. The shares dropped from a high of £13 something to about 0.35p - a drop to about 1/4000 of their top price! Shades of Enron.........I didn't sell, so effectively lost about £60,000. The military side went to BAE Systems, and I still work for the semiconductor side, albeit it's a different name and product line.
73
Peter G3RZP