Sony ICF-SW77 manual Introduction, System overview, Change of 455 kHz IF filter, 3.1Schematic

1 Introduction

1.1Purpose of this document

This document describes how to modify a Sony ICF-SW77 short wave receiver to be able to receive a DRM signal. Therefore the DRM – Miniature Mixer Unit from Sat-Service Schneider is used, to mix down the 455 kHz IF of the receiver to a 12 kHz IF. This 12 kHz IF is feed to a PC sound card.

Please note that the manufacturer's warranty will be discarded if you do this modification.

1.2Organization of this document

Chapter 1 provides an introduction to the document. Chapter 2 provides an overview of the system.

Chapter 3 describes how the IF filter of the ICF-SW77 has to be changed.

Chapter 4 describes how the DRM Miniature Mixer Unit has to be connected to the receiver.

2 System overview

The 2. IF (455 kHz) of the ICF-SW77 receiver is feed to the miniature mixer unit and down converted to a 12 kHz IF. This IF signal is then connected to the input of a PC sound card. This PC decodes the DRM signal with a decoder software.

ICF-SW77

455 kHz

mixer unit

12 kHz

PC

3 Change of 455 kHz IF filter

The bandwidth of the ICF-SW77 receiver is too small to receive a DRM signal. Therefore the IF filter has to be changed.

3.1Schematic

The following diagram shows the schematic of the SW 77 IF section.

Date: 19-11-02 Page 3 of 8