[Amps] The GU84B and GU78B tubes / some brief history

[peter chadwick]

Once one got above 2 to 3 kW, grounded grid amplifiers started appearing in commercial European  transmitters in the 1950s, and especially when drivers of around 7kW became more common,  GG amps were used to get up to the 100 to 150kW level. Before that time, triodes were used quite extensively in neutralised amplifiers, often in push-pull.
In amateur service, probably the most manufactured amplifiers were the KW Electronics KW600 and KW1000. One 572B in the KW600, and two in the KW1000. Both were also made in 4 channel commercial models. 
Peter G3RZP