Burkhard Kainka
About the article

Build Your Own DRM Receiver

A digital radio for 500 kHz to 22 MHz

Build Your Own DRM Receiver
One again Elektor Electronics makes its competitors take a very distant back seat by publishing the world’s first homebuilt DRM receiver for digital (MP4-quality) broadcasts in the medium and shortwave bands. The receiver is of a surprisingly simple design and supplies a 12-kHz output signal for easy connection to your PC’s soundcard which handles the demodulation and MPEG decoding. The receiver is also tuned by the PC via an RS232 link.On 15 December 2003, DRM (Digital Radio Mondial) entered a new phase on the shortwave and medium-wave bands. The encoding was changed to MP4 in order to improve the quality of the received audio signals even further. The unique receiver described in this article was developed for all readers interested in listening to DRM broadcasts at a modest investment.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Extra info / Update
New software has been developed for this project that allows an USB/RS232 adapter to be used. This means the receiver can now be controlled from a laptop without a serial port. Free Download
Component list
R1 = 3kOhm 9
R2 = 680Ohm
R3 = 330Ohm
R4 = 180Ohm
R5 = 39Ohm Ohm
R6,R13 = 100kOhm
R7,R9 = 100Ohm
R8,R10 = 2kOhm 2
R11 = 220kOhm
R12 = 1kOhm
R14 = 3kOhm 3
R15,R16 = 560kOhm
R17 = 27kOhm
R18 = 220kOhm
C1-C4 = 100nF, SMD, case shape 1208
C5,C6 = 15pF
C7,C8,C11,C14,C17,C23,C24,C25 = 100nF, lead pitch 5mm
C9 = 1nF8, lead pitch 5mm
C10 = 3nF3, lead pitch 5mm
C12,C13,C21 = 4µ F7 16V radial
C15,C16 = 470pF
C18,C19 = 1nF, lead pitch 5mm
C20 = 4nF7, lead pitch 5mm
C22 = 470nF
L1 = 3µ H3
L2 = 10µ H
L3 = 100µ H
D1 = 1N4001
T1,T2 = BF494
T3 = BC548C, BC549C or BC550C
T4 = BF245C
IC1 = MC1489N
IC2 = AD9835 BRU (Analog Devices)
IC3 = LM358N
IC4 = 7805
IC5 = 50MHz oscillator module in 8-way or 14-way DIP case
K1 = 9-way sub-D socket (female), angled pins, PCB mount
K2 = 2 solder pins
K3 = mains adapter socket
K4 = cable with 3.5-mm mono or stereo jack plug
MIX1 = TUF-1 (Mini Circuits)
FL1 = CFW455F (455kHz ceramic filter, bandwidth 12kHz) (Murata)
X1 = CSB470 (470kHz ceramic resonator) (Murata)
RS232 cable with 1:1 pin connections, plug and socket, no zero-modem or crossed wire cable.
PCB, order code 030365-1
Disk, PC software DRM.exe, order code 030365-11 or Free Download
Suggested component / kit suppliers:
- Geist Electronic (www.geist-electronic.de)
- Segor electronics (www.segor.de).
- AK Modul Bus (www.ak-modul-bus.de)
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