EB5AGV's Workbench: Kenwood R-5000 DRM addition

The Kenwood R-5000 is a well known all mode (AM/FM/USB/LSB/CW) General Coverage Communications Receiver, which covers LF, MF and HF bands (100-30000kHz) and, with an optional converter (VC-20), VHF (108-174MHz).

I got one some months ago, with all the extra filters on it along the VS-1 Voice Synthesizer module. It was missing the VHF converter option but I was able to locate one so it was full equipe. But, as I have lots of other equipment and, due to it being a USA model, with only 120Vac power option and having not a proper 12Vdc power connector, it had been sitting unused for some time.

But some days ago there was a comment about DRM (Digital Radio Mondiale) which sparked my interest. And, when I found that the R-5000 was suitable for a simple mod to work on that novel mode, I was hooked and determined to try it.

I was directed by a fellow ham to the Crispino Messina I5XWW page, where he offers a nice DRM converter kit for a very reasonable price (15 Euro, shipping to Spain included, as of December 2006). So I immediately ordered it and was glad to receive it in just few days. Great work, Crispino!

You can get the unit already assembled for just an small extra amount but I enjoy building electronic circuits so I got it in kit mode:

As you can see, kit is composed of a PCB, an IC and some discrete components. It is sent along a simple instruction sheet which is more than enough to mount it in just some minutes. Here you have the finished converter:

It has a couple adjustments: one is for the oscillator frequency. It is adjusted by a trimmer and should be zero beated with 467kHz. I did it using my Yaesu FT-890 in SSB mode, tuned at 467.00kHz and looking for a zero beat. The other adjustment is for signal output level (will be discussed later).

The 455kHz to 12kHz converter should be wired to a proper location in the R-5000 455kHz IF, in the IF UNIT (located just under top cover). There are several WEB pages depicting this procedure but I will put my own pictures as they could help other people.

You need to get the signal from R193 and ground. Here you have the location of R193:

You need to remove all IF UNIT screws and then put some protection over the R-5000 front panel top and carefully lay the unit, with all wires attached, over the front panel top. Here you have the exact point where I connected the RG-174 coax wire:

One thing which is also needed is to power the converter. It needs a 9 to 12Vdc voltage source. As you need also to place the converter somewhere in the R-5000 I found that a good point, close both to a power source and to the signal pick-up point, was the heatsink in the voltage regulator assembly, using double sided adhesive tape. I used an extra layer of adhesive rubber to get a good fit:

That place is also good as it does not interfere with the VHF converter (not shown in pictures).

Here you have the power supply heathsink:

Add here where I connected the power supply to the converter, previously lifting the power supply assembly:

This is a general view with the converter on place. Neat!

I got everything back to its original place except for the top cover, as it should be off to adjust the signal out level pot on the converter. Then I installed the DREAM software for Windows in my trusty IBM Thinkpad T20. There are other interesting programs here, but I recommend starting with DREAM.

I hooked the output signal from the converter to the LINE IN port of the T20. Then I opened the AUDIO MIXER and selected LINE IN as the only input signal to the audio card.

First DRM station I knew of was Deutsche Welle at 3995kHz, so I tuned the R-5000 there:

I run the DREAM program, opened the SYSTEM EVALUATION window, which starts with INPUT PSD option. Playing a bit with the ATTenuator (as signal was 9+50dB) and the converter audio level pot, I was able to get a really clear reception with DREAM:


It seemed that without attenuator, signal got distorted and reception failed. Tuning other radio stations I tried several receiver settings and it seems a 9 to 9+10dB signal is the best for a good reception, so I used the ATTenuator accordingly and got nice looking INPUT PSD graphs and also great reception quality. DREAM is a very powerful program which I have just started to use but I like it a lot so far. Other options, as waterfall display or signal constellations are great to check the received signal quality and to learn a bit about the DRM internals.

All in all, I am very happy with this 'new' mode and hope to use it extensively, armed with my upgraded R-5000.

I would appreciate your feedback about this page, in order to upgrade and update it and also your experiences with DRM and/or R-5000. Thanks!.