DAB radio signal using the rear screen antennas

I've found that it is possible to use the existing rear screen antenna to feed a DAB / FM radio signal to a head unit.
I disconnected all of the wiring from the existing antenna amplifier (apart from the ground feed to and from the heated rear screen of course).
The 12v feed from the head unit was used to power the a new amplifier (A4721.01 about £50 from www.co-star.co.uk).
I also purchsed some FAKRA Female Water Blue connectors from the same place so that the input and output signals could be connected to the amplifier.
I connected both rear screen antenna wires together before feeding them into the amplifier.
I used the existing FM/AM cable and I already had another SMB co-ax cable in place for the DAB signal from an earlier failed attempt using an E-bay amplifier that proved to be rubbish!
My head unit is a Pure Highway H260DBi and I'm getting 4 out of 4 bars DAB signal strength on many stations

Hats off to you,

That's a commitment to listening to "tunes" while your at the wheel. And looks to be a very good upgrade.

I'm still on the original stereo...now where are my mix tapes :-)

Regards

MM

This is a very tempting mod - the internal aerials work up to a point but I haven't found them ultra-reliable

Agreed, I've been looking at it too, here's a link to the suggested amplifier https://www.co-star.co.uk/3669/dab-in-car-digital-radio-amplifier-a-4721-01/

I can't quite work out the wiring arrangement that is referred to however, perhaps MIB can give us a nice diagram? In particular, is there a DAB aerial anywhere? I was thinking of something like this https://www.co-star.co.uk/3839/dab-glass-mount-antenna-gmdab3l-5f/

Part of the reason for this mod is that I didn't want to use one of those ugly stick on DAB antennas
The heated screen elements are all the antennas needed. In fact DAB signals are horizontally polarised, so the rear screen antenna is ideal!
The reason that an amplifier was used in the first place is to boost the FM/AM signals, which are transmitted by vertical antennas, to make up for the inherent losses when trying to receive a signal with a cross polarised receive antenna.

If I was to do this mod from scratch, I would do the following:

For the AM/FM signal output from the new amplifier to the radio Google 'Female FAKRA to Male Din 5m cable'.

For the DAB signal output from the new amplifier to the radio Google 'Female FAKRA to SMB 5m cable'.

Run these two cables from the new amplifier down the nearside of the car behind the left rear speaker, under the carpet by the passenger door and over the footwell to the radio.

Google 'Female FAKRA cable repair kit'. This is FAKRA connector to a flying coax lead.
Solder the centre wire of this coax (make sure to not connect the coax outer screen to anything) to the ends of cables 2 and 3 in the attached picture. This connects together the two AM and FM antennas built into the rear screen and their received signals are now used as the input to the new radio amplifier.

I think that this is a far better way to do it than my bit of a bodge up!

I've just installed a Sony DAB head unit, and the supplied antenna is pretty naff, so I'm thinking of trying your mod. Looking at the original amplifier here http://www.bugone.co.uk/fiat/antenna_booster.htm it looks like the coax cable is connected by some sort of threaded socket. A better view here https://www.ebay.co.uk/itm/Amplifie...-00-Original-Code-46304204-/253473324132

Now, wouldn't it be possible to get a FAKRA adapter, something like this maybe https://www.co-star.co.uk/3754/sma-female-to-fakra-female-waterblue-antenna-adaptor-cff-smaj-neuj/ to save butchering and soldering the original cable? Just don't know type of socket it is.

Looks like that adapter is Fakra to SMA. The connector used on the original radio amplifier for the radio is not SMA so this is no good for you. I don't know what Fiat have used, but it doesn't look standard!
As you will need to run a female Fakra to SMB cable from the new amplifier to the radio for the DAB signal, I would also buy a female Fakra to male DIN for the FM signal at the same time.

I've got the same Pure dab radio in mine but using a stick-on film aerial on the front screen(from halfords) on the n/s, work OK and doesn't look bad. Didn't think of using the existing

Would this be the right cable for DAB connection to the German radio amp suggested?

Fakra to SMB 5m

I'm in the process of investigating this mod, not only to dispense with the stick-on windscreen aerial but to improve reception.

Reading this very informative article posted by a retail establishment in Yorkshire it reckons that DAB transmissions are actually vertical, although if the coupe rear screen aerial does better than the adhesive one I'm fine with that! Indeed I was advised to align mine the same way after having originally located it horizontally - but tbh I didn't gain much difference.

A further website Jim's Aerials continues...

At the outset, DAB stations were allocated a high data rate giving excellent sound quality. More recently, this bandwidth has been reduced, with the sound quality suffering accordingly. The digital radio offered on satellite transmission currently has a better quality than DAB.


So I'm wondering whether the drop-off in reception on my stick-on aerial might have something to do with that...

Yes mate, that's the one, assuming the DAB input on the back of your head unit is an SMB male plug. After loads of searching, I've found this https://www.dabonwheels.co.uk/what-do-the-aerial-connectors-look-like/ It looks like the socket on the original amp in the coupe is a Hirschmann male plug, it seems to be a much less common version of the F connector with the thread on the outside rather than inside. As well as the FAKRA to SMB cable, I'll be ordering this https://www.dabonwheels.co.uk/product/dow-6-fakra-f-to-hirschmann-m/ to join the coax to the new amp/splitter. It's a bit of a punt, so fingers crossed it fits!

I'll get Joe to have a quick look as I don't have mine at the moment!



Joe

Well I've taken the plunge and ordered the DAB lead and the amp - someone has just given me a £25 voucher for Amazon which worked out the cheapest anyway, so I'm rockin'

No. That doesn't affect the DAB broadcast signal strength - just the bandwidth (number of bits per second) allocated to each channel. The amount of data remains constant but it's shared between more audio channels, to the general unhappiness of listeners.

Neil

I used a dual FM/DAB (1 input 2 outputs - DAB and FM) adaptor (a few quid) to wire the standard rear screen amplified signal straight to my DAB/FM head unit and it works fantastically with both DAB and FM. The adaptor was the only additional cost. Signal strength is great!