ICOM IC-R71E modification for DRM reception

BOM:
Murata CFK455F filter
455kHz to 12kHz crystal converter by http:\\www.sat-schneider.de
RCA female connector 
Shielded cable for audio
Cable for voltage
Material to tighten the converter board

Modification:

Receiver, which was modified, doesn't have FM option installed. Therefore, it was easy to use the connector J10 for the output of the 455kHz signal on the top side of the receiver. The pin closer to rear side of the receiver in the J10 connector is the 455kHz signal output and the other pin is ground. 

1. Solder the voltage cable and the audio cable to converter board. 
2. Solder the output pins of the filter directly to the converter board. The legs of the filter needs to be bended carefully to match the holes on the converter board. 
3. The signal input pin of the filter was soldered directly to the output pin of the 455kHz of the J10. The ground pin of the filter in the input of the filter was soldered with short cable to the connector J10 ground pin. 
4. Finally, the +8V voltage was taken from resistor R156 at the point closer to rear panel. 

Adjustment: 

Press the filter button W down and verify the filter button N is up.
Use the AM demodulation mode.

Before turning on the receiver, make sure the trimmerpot on the converter board is adjusted to its maximum attenuation, with other words, to the minimum resistance between output of the trimmerpot and ground. The level of the input to the converter board shall not be higher than 100mV. I used oscilloscope to find a level between 25mV to 50mV when in the input of the receiver was an AM modulated signal with modulation depth 78%. If you don't have an AM signal generator available it might be possible to adjust the trimmerpot to maximum attenuation and use the DRM PC software to adjust the attenuation. Note also that the 455kHz signal output at the J10 has high level, approx. 800mV and 4V DC offset. Insertion loss of the filter is 6dB.