Modification of Sony ICF-SW 7600GR for DRM
This receiver (like the old model SW7600G) has a 2nd IF of 455kHz, so the SATSchneider crystal mixer can be used for downconverting the IF to 12 kHz. As there is not enough space inside the receiver, I put the mixer board, together with a 9V battery and a filter CFW455F in an extra case. I tapped the signal before it enters the IF filter on the board (CF201, see picture below) and connected it to the receivers line out jack (for listening to AM you can still use the earphone jack).
Pic 1: schematics showing CF201
Pic 2: showing CF201 on the PCB For the connection use a shielded wire and connect the shield to ground next to the signal. The other end of the wire can be connected to the line out after removing the capacitors C248 and C250.
Pic 3: showing the line out connection
In the extra box put the filter CFW 455F in font of the mixer board. All you would need for this is: 1 filter CFW 455F 1 crystal mixer board (both available from SAT-Service Schneider) a piece of coax cable and a 9V battery Its a simple modification but it has been working great, even with the telescopic antenna, on some transmissions I achieved up to 27 dB SNR and I especially like it for receiving DRM on medium wave with the built-in ferrite antenna. For the old model SW7600G it is nearly the same, except the point for tapping the IF is CF401 instead of CF201, and the capacitors that need to be removed are C 421 and C423.
If you are interested in the complete service manual of the SW7600GR as a pdf file or for further questions, send me an email to: stoeppler@yahoo.com
Simone Stoeppler stoeppler@yahoo.com www.stoepplernet.de/DRM/

Feb 2004