PRODUCTION ENGINEERING MEASURE. CR-(XM53/U QUARTZ CRYSTAL UNITS.

During the third period, the development of crystal unit designs was nearly completed. Designs for the crystal resonators themselves were established, and designs for the mounting assemblies were nearly completed. A special claw mounting arrangement was developed when adapted to the 1-megacycle units, it greatly improved Q levels, but it was not as adaptable to the higher frequencies because of their thinner quartz plates. As a result, it has been found impractical to meet the millionQ goal at frequencies above two megacycles with production-type units. Revised requirements of 0.9-million at 3 Mc, 0.8-million at 4 Mc, and 0.6-million at 5 Mc have been proposed. The equipment and procedures for conducting the 6-month reliability study have been established and are being checked out by use on experimental units. The arrangement provides practical means of making weekly frequency headings on 1000 units by using special holding jigs to position crystals in precision oilbath temperature controllers and using transistor oscillators which connect directly to terminals on the positioning jigs. Readings are recorded by a digital printer. Author