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Sangean ATS 909 IF-Output for DRM

by Markus März, DO5MM,

 
 
 
 
Before you start to modify your receiver, I recommend that you read other modification instructions in the "Documents" section on drmrx.org as well as messages in the  "Receiver  Modifications" forum to get an idea of potential problems you may face.

I will take no responsibility for any damage, injury or losses which arise from the use of the following  information. 

This document describes where to tap the if-signal, which has to be fed into the mixer unit.
I'm using a homebrew mixer based on the design by Edgar Kaiser, who uses a cheap and easily available Crystal Oscillator to downconvert the 450KHz IF-signal to 12KHz, suitable to be processed by pc-soundcards.

This Receiver is also known as Siemens RK777, Radio Shack DX-398, Roberts R861 and TechniSat ATS 909.
It has a second IF of 450KHz
Because the two if-filters are too narrow for proper DRM-reception, the signal has to be tapped before the filters.
 
 
909 schem
Source: Siemens AG, Schematic of Siemens RK777G6 World Band Receiver 
 

Backsideview of the pcb.

backsideview pcb
 
 

Detailed view of the IF-section. The inner wire of the cable(RG178) is soldered to capacitor C29, shield  is soldered to the ground track above.

pcb detailed view
 
 

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