Adding DAB+ (and Blutooth and even Handsfree) to your classic benz

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Posts: 1033
Joined: Sat 25 Apr, 2009 9:32 am
Model you own: w123
Location: Melbourne, Vic

Adding DAB+ (and Blutooth and even Handsfree) to your classic benz

Post by tsharkey » Sun 17 Feb, 2019 9:16 pm

I have been using digital radio in the daily driver and just added another one to Hektor. If you are in a digital reception area (capitals only sorry), DAB+ allows for cleaner reception than FM and much better quality than AM. There is also a greater range of stations to listen to (eg: main stations have a lot of secondary ones, particularly the ABC and SBS). I kept the original Beckers in situ and opted for an after market unit designed in the UK by Pure plc. I am sure there are other equally capable adapters and whilst I am happy to attest to the success of the units for me, this is not really an endorsement of them.

Bill of Materials
1. Pure Highway 300 kit
PureHighway DAB.JPG
2. MPoW Bluetooth Adaptor (with handsfree)
3. 1 x DIN (Male) to ISO (Female) – Plugs into back of radio to convert to ISO
ISO Adapter 2.JPG
4. DIN Male to Male, 0.5m length – Between DAB unit and Becker

5. 1 x DIN (Female) to ISO (Male) adapter – DAB unit and Antenna line
ISO Adaptor.JPG
6. Hirschmann Antenna limiter kit
(see second half of article below)

Electrical connections
1. 12v Always Power – F2. Can also tap into line into becker
2. 12 v Ignition - F4. Can also tap into Cigarette Lighter line
3. Spade connector double adapter for 12v Trigger out from Radio

1. Connect DAB unit to Power, Ignition and Trigger
2. Connect on DAB antenna RF line IN adaptor and then antenna
3. Connect on DAB RF line OUT adaptor then ISO extension to radio
4. Plug MPoW USB into USB socket of Pure Highway (will provide Power to Blutooth when PureHighway is on)
5. Plug MPoW 3.5mm audio into LineIn / Aux on Pure Highway

1. The Pure Highway control unit sites between glove box and heater box (in W123).
2. The control unit sits on an empty switch in top of console switch bank
3. The MPoW sites on dash pad, above console switch and under trim switch

Getting the Tunes
1. Set Pure Highway to “inject” its FM signal with other stations [Installer mode]
2. Set frequency on Pure Highway to be empty FM channel – I use 99.9 or 107.9 depending
3. Set Becker to spare frequency
4. Pure Highway will auto tune and find a gazillion stations.
5. Blutooth is “AUX In” on PureHighway. Pair to MPoW.

1. If using blutooth, the phone rings - Hit the middle button and you can speak.

Hirschmann Limiter Kit
DAB+ in AU uses 200Mhz which is 1.5m band. At full length, the Hirschmann will not get you optimal reception, in reception will drop out when driving around town. You can fit a DAB specific antenna but I didn’t like the look of it on an old benz.

Instead I designed a kit to switch the Hirschmann off once about 37.5cm has extended (1/4 wave). The radio gives fantastic reception all around town.

When the 12v trigger from the radio fires up the Hirschamann, 12v always on power is cut after 3 seconds, so the Antenna doesn’t fully extend. When the trigger 12v is dropped, the relay reverts back and the antenna retracts. Below is my anal retentive way, which doesn’t mess with the original cabling, uses standard benz plugs and triggers a second relay as the antenna does pull a bit of current (the control module alleges to be able to cope with 10A but looking at the relay, not so sure). You could dispense with most of that and cut the line, inserting the control module but that’s not my style.


Apologies for the handdrawn diagram and lack of technical correctness - Its what I work off ....

Bill of Materials
1. Standard Relay
2. Delay on Timer module (plenty on eBay)
3. Benz style 4 pin male plug – Intercept line to antenna
4. Benz style 4 pin female plug – Plug into Antenna
5. Benz style 6 pin female plug x 2 – 1 for relay, 1 to plug into the intercept harness
6. Benz style 6 pin male plug - Antenna lines connect to it
7. Mounting bracket
8. Plastic Case from Jaycar
Items #3 to #7 should be got from any old benz wreck.

1. Desolder all the pins from the 5 recovered plugs
2. Solder up the Intercept harness (4 pin male to 6 pin female to 4 pin male) as per the wiring diagrams
Intercept Loom.JPG
3. Solder up the 6 pin male plug, 6 pin female (Relay) and delay time module
Control Harness.JPG
You can see I have mounted washers on the back of the plugs - they will hold the plugs into the plastic case by to sit in the retaining grooves of the housing.

4. Assemble (not in the case) and test – calibrating the delay to about 3 seconds which equates to 37.5cms


5. To make the job neat, I mounted using a spare plug bracket.
Finished Mounted .JPG
If I want to extend the antenna fully, I plan to add an override switch that kills the output to 86 on the relay, thereby never allowing the power to be cut. I have an antenna switch from a US car which will be mounted next to the DAB unit.
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W123 1981 300TD - Family Kid mover
W202 1998 C250D Factory OM605A Turbo - Partner's daily driver
W123 1982 300CD Retro fitted OM617A Turbo - Mine
W123 1984 300TD English 5 Speed Manual
W123 1982 300TD Factory OM617A Turbo (Hans) - Project
W123 1982 300D - OM617 NA (Hektor) - Son's
W123 1985 230TE - Brother's
W123 1985 300D - Sister in Law's
1962 S-Series Valiant (Tho Daimler & Chrysler divorced, still part of the extended family)

Past benzes
W114 1969 250CE - PO put in an M110 transplant and nearly sent me around the bend
W123 1981 300TD - "Matilda" - RIP hit front side & rear but left my brother + niece A-OK

Current Projects
Coupe restoration, Turbo Wagon freshen up

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Joined: Mon 10 Apr, 2006 12:47 am
Model you own: w107
Location: Weinheim / Germany

Re: Adding DAB+ (and Blutooth and even Handsfree) to your classic benz

Post by T-Modell » Sun 17 Feb, 2019 9:52 pm

Great report and solution, congrats! As I like fiddling too, it's always interesting what others come up with.

In 2006 (wasn't allowed then in Germany) I bought one of those FM Transmitters for the ipod. However, here in Germany, there's hardly an "empty" frequency left, so if you drive longer distances, it can happen that you have to change the FM frequency, because in another area a radio station uses it.

Might be completely different in Oz. If those things get a bit smaller, they could be integrated - like the mp3 in my retro radio - into the radio by removing the cassette part.

1967 W111 250SE Cabriolet, horizon blue
1973 W115 220D 5.0 Pick-Up Argentina, solar orange, work in progress 2017-2020
1986 R107 500SL, arctic white, the midlife crisis viagra replacement
2007 R171 SLK350, calcit white
2019 W222 S560, ruby black, comfy cruiser

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