Modifying a JRC NRD-525 for DRM reception

Making space for the DRM Interface

C56 and C102 on the IF-AF Amp board of the NRD525 were moved to the solderside in order to make some space for the DRM-Interface.
DRM making space for the DRM interface
Input to the DRM I/F is TP1.

The output is connected to pin 15 of motherboardconnector P28.

The 10.8 Volt DC is obtained from L3.

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DRM Input to the DRM I/F

Output of the DRM I/F

The black (RG174) coax connects one of the Scope outputs (bottom right) to the output of the DRM I/F via pin 15.
This can only be done if the RTTY I/F is not fitted!
DRM Output of the DRM I/F

Extended filter switching

A new firmware (V1.4) in combination with some simple hardware modification results in bypassing the 455 kHz filters FL1 - FL4 resulting in a 455 kHz bandwidth of about 12 kHz necessary for the DRM I/F.

See for more details:
French manual NRD525
English manual NRD525
DRM Website NRD-525 a la loupe (French)

New backpanel connectors

The SO239 type bulkhead connectors for the VHF / UHF were replaced by N-type bulkheads.

The original RS-232 connector was replaced by an DB9 type.

DRM New backplane connectors

RS232 connector

DRM RS232 connector at back of set