. QST . ower required totransmit reliably a given rate of informationapproaches infinity.) In the circuit design to follow, an amplifierbandwidth of 100 cycles is chosen because thisbandwidth is easily obtained with presently-available circuit components. Additional narrow-band audio-frequency filters can be used if neces-sary after the signal is tuned in. The over-all cir-cuit stability (from transmitter to receiver) re- 30 QST for DISK AND SLUG Fig. 1D-25/17,5). without affecting the Q. The effectiveinductance is slightly increased bygrounding the core, since the distributedcapacity effects
. QST . ower required totransmit reliably a given rate of informationapproaches infinity.) In the circuit design to follow, an amplifierbandwidth of 100 cycles is chosen because thisbandwidth is easily obtained with presently-available circuit components. Additional narrow-band audio-frequency filters can be used if neces-sary after the signal is tuned in. The over-all cir-cuit stability (from transmitter to receiver) re- 30 QST for DISK AND SLUG Fig. 1D-25/17,5). without affecting the Q. The effectiveinductance is slightly increased bygrounding the core, since the distributedcapacity effects are changed. However,this is only of the order of a few nfii. Theupjjer frequency limit for Ferroxcubetuned inductors is about 500 kc. Application of Pot Cores Cross section of assembly If the tuned filter is to be used as the, , , ,„ . load impedance of a tuned amplifier, Component parts and assembled pot core (rerroxcube ■ , „:j„ „j.: „ . ^„ * *^ f ^ some special considerations are neces-. quired for operation with a 100-cycle filter is suchas to require fine vernier action for the oscilla-tor control, in order to hold the signal in thepassband. Ferroxcube Pot Cores If an ail-wound coil is placed in a medium ofpermeability ju times that of air, the s!»lf-induct-ance L will also be increased yu times. Since thecopper losses remain constant, the Q of the in-ductor will be increased. The resultant increase ofthe qualitA factor will depend on the additionallosses introduced into the coil by the core. Theselosses may comprise eddy-current losses, hys-teresis losses, and residual core losses. Recently,great advances have been made by manufac-turers in producing ferromagnetic materialswhich introduce very small losses. FerroxcubeIII is a low-loss manganese-zinc ferrite witha cubic crystal structure. The metal oxides areextruded in the form of a plastic mass and fired ata high temperature; the result is a material ofextremely high resistivity and having mechanical
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
