‘A ‘mystery effect’ in silicon has been harnessed by RCA to produce the most powerful pulses of radio energy in the UHF range yet achieved by a solid state device’, reported Electronics Weekly in its Nov 26 1969 edition.
'The phenomenon occurs in avalanche diodes when they are placed in an electronic circuit tuned to oscillate at radio frequencies lower than those at which the diodes are supposed to be able to oscillate,’ continues the EW report.
‘When electrical pulses are applied to diodes, they abruptly enter an ‘anomalous mode’ of operation, and begin to produce microwave oscillations with powers and efficiencies substantially higher than they can normally produce. The reasons for this are still not fully understood.’
Dr William Webster, vice president of RCA’s Princeton labs, which discovered the phenomenon, said that, by combining five such devices in a single package, and operating them in the anomalous mode, “We have now succeeded in producing micro-wave pulses with peak powers above1,200W, powers which only electron tubes have been able to attain until now, and with efficiencies above 25 per cent.”
Was this the famous tunnel diode? I would have thought not, since I remember playing with such a device before 1965, until it quit!