SRC-559

Microwave Beamed Power Technology Improvement, Final Report -- Raytheon report PT-5613; JPL Contract No. 955104; 15 May 1980

Commissioned by Jet Propulsion Laboratory (Caltech), sponsored by NASA under Contract NAS 7-100; JPL subcontract 955104. Who paid for a study is recorded because it bears on how its conclusions should be read, not because it makes them wrong.

Published claims resting on this source

• CLM-1044 In 1980 the quiet oven magnetron was already beyond the instrument's reach: at least 155 decibels below carrier per hertz away from the carrier, quieter at low magnetic field and high current, unaffected by drive level. Close to the carrier its added phase noise was about 114 decibels down per kilohertz at 50 kilohertz.
• CLM-1045 Raytheon's own numbers had the klystron just failing the interference limit at the band edge and the magnetron clearing it by 45 decibels, while conceding nobody had measured a klystron that close to its carrier and that near the carrier the klystron was slightly quieter.
• CLM-1047 The oven magnetron's second harmonic came out about 70 decibels below its carrier, a tuned stub took another 40 off, and the antenna's own pattern was credited with 65 more, so Raytheon reckoned the whole satellite's second harmonic would arrive on the ground fifty decibels under the limit. The third, fourth and fifth were measured but never filtered, and the fifth was unexpectedly strong.
• CLM-1048 A cheap oven magnetron run cold and hard converted 81.7 per cent of its DC input to microwaves, measured carefully by heating water. Raytheon's point was that theory said 94 and a lower-frequency tube already did 93, so the 2.45 GHz tube was leaving six points on the table nobody had explained.
• CLM-1049 The fifty-year magnetron rests on a cathode that runs cool because the tube heats it only as much as it needs, on tube-life curves from 1950s transmitter valves, and on twelve radio-station valves that ran ten years without failing. No magnetron had been life-tested that way, and the test tubes Raytheon looked into poisoned themselves in under an hour.
• CLM-1050 The interference limit Raytheon measured its tubes against is given as a CCIR requirement but never traced to a CCIR document, and one page even gets its units wrong by a factor of a thousand.

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