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 Â13 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 Â60,000. 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
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