Home made receiver

[electro2005]

I have been tinkering with DRM for a few weeks and because it seemed to work I set to and built a dedicated receiver.
I modified my Icom IC735 with a CFW455F AM filter to open up the bandwidth and took an IF tap to the 8 pin rear socket.
I could not find a 443Khz crystal so I used an old MC145151 synthesiser IC along with the mixer IC SA602 type.
I added an LCD display to show the frequency just to use up old parts.

Its a bit of overkill really but it did not cost anything apart for a clock IC to generate the comparitor frequency for the Synthesiser.

I have to say I am amazed about the audio quality, an signal over 16 dB S/N gives crystal clear audio.

This may not be the place to say this but it turns out that DRM software is more tolerant than Dream of drop outs of signal.
Currently RTL Radio on 6095Khz is 20dB S/N and is perfect.

regards

[CT4RK]

Hi electro2005
My solution for 443 KHz XTAL was an color cristal from an old TV set, and a decade counter dividing by 10. This downconverter working very fine. I atach the diagram of the downconverter to this msg with one TCA440 receiver that Iwas build in the last year. For the LO receiver I was used a DDS. You can add a preselector for best performance.

[CT4RK]

TCA440 receiver is like this.

[CT4RK]

The PCB layout with downconverter include.