. QST . t 250 to 700 kc. ifjR the higher frequencies we have only one alternate to consider, and that is mechanical filters em-ploying the piezo electric effect. Of all the materials exhibiting this effect only quartz has the necessarvphysical properties, permitting the fabrication of thin, small elements which can be combined into afilter network. The upper frequency limit of quartz filters is quite high and may reach as much as15 to 20 Mc. 1 HE fabrication of quartz crystals has progressed amazingly since 1940 and, likewise, the scientificknowledge of the application of quartz elements in ba
. QST . t 250 to 700 kc. ifjR the higher frequencies we have only one alternate to consider, and that is mechanical filters em-ploying the piezo electric effect. Of all the materials exhibiting this effect only quartz has the necessarvphysical properties, permitting the fabrication of thin, small elements which can be combined into afilter network. The upper frequency limit of quartz filters is quite high and may reach as much as15 to 20 Mc. 1 HE fabrication of quartz crystals has progressed amazingly since 1940 and, likewise, the scientificknowledge of the application of quartz elements in bandpass networks. It seems logical, therefore, thatfurther research may soon find methods of obtaining adjustable passbands with one crystal network,thus affording a very versatile new device for the design engineer. —Fritz Franke {i^l^M^,^. U). ^• U^^^^^-^^ VPAC ^o* [^allicrafters ADVERTISEMENT 77 NEAR MULTIPHASE 600 L NO TUNINGCONTROLS SINGLE KNOB BAND-SWITCHING 10-160 FOR USE ONSSB, AM, PM & CW.
Size: 2062px × 1212px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
