Instruction/ maintenance manual of the product ICF-SW77 Sony
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Date: 19-11-02 Pa g e 1 o f 8 Modification of So n y ICF -SW77 for DRM Software receiver.
Date: 19-11-02 Pa g e 2 o f 8 Table of Contents 1 INTRO D UCTION ................................ ................................ ................................ ................................ ......... 3 1.1 P URPOSE O F T H I S DOCUMENT ........
Date: 19-11-02 Pa g e 3 o f 8 1 Introduction 1.1 Purpose of this d o cument This document describes how to modif y a So n y I CF - SW77 short wave rece i ver to be able to recei v e a DRM s i g nal. T heref o re the DRM – Mi n iature Mi x er Unit from Sat- Service Schneider is used, to mix down the 455 kHz I F of the receiver to a 12 k Hz I F.
Date: 19-11-02 Pa g e 4 o f 8 w i de band fil ter n arrow ba n d fil t er Z F in GND The I F s ection has two IF filters, a n arr o w band f i lter and a wide b and filter. One of the s e filters has to be rep l aced b y a wi der filter with ap p r. 10 kHz bandwidth.
Date: 19-11-02 Pa g e 5 o f 8 3.2 Filter ban d w idth The with the receiver su p plied wide band I F filter has a bandwidth ob ap p r . +/ - 3 kHz. The bandwidth is shown in followin g dia g ram: The recommended replacement filter is a Mura t a CFWM455GY, which has the same footprint as the or i g inal filter, but a bandwidth of appr.
Date: 19-11-02 Pa g e 6 o f 8 3.3 IF Filter t y pes The followin g M u rata fi l ter t y p es are fittin g into the I F filter footprint in the SW77 receiver: Part Nu m ber 6 dB bandwidth CFWM455G +/- 4.
Date: 19-11-02 Pa g e 7 o f 8 4.1 P o w er supply The mi x er unit needs a power supp l y with 7 -20 V DC. Unfortunate l y the receiver supplies a ma x imum v o lta g e of 6 V. Test showed that it is possible to use the 6V instead of the 7-20 V to run the mi x er unit.
Date: 19-11-02 Pa g e 8 o f 8.
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