[Amps] Solid state or tubes for HPAs

[John Lyles]

Wednesday at the North American Particle Accelerator Conference in
Pasadena, I presented my poster on the merits and problems of choosing
transistors, IOTs, klystrons or tetrodes for VHF HPAs. The engineer from 
another institution who was next to me had made a compact 6 kW CW amp at 
1.3 GHz using RFMD gallium nitride transistors, 63 % efficient,linear, 
64 transistors, water cooled. Quite impressive.

The biggest SSPA is in France - 180 kW CW at 352 MHz using DMOS. Some 
newer versions are being built for other synchrotrons using LDMOS with 
NXP devices. Even so, these amplifiers will fill the space of a garage 
due to the combiners and splitters. Approximately 750 devices.

My topic was the bad boy tetrode HPA at 200 MHz for 3.6 MW peak power,
420 kW average power. Its commercial now, first units coming out of 
manufacturing. Try doing that with silicon.
73
John
K5PRO