Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Where to fit that DAB Radio/ CD player??????

Steve,

yes, an aerial needs an earthed ground field: on most cars this is the body. If you use the luggage rack simply earthing that may well work.

The "electronic" aerials work differently, but need a power supply as they have an amplifier built in. To be honest sorting out the aerial is the hardest part of the DAB instalation.

As it's a magmount, the base is capacitively coupled to the car's body.
The protective coating on the base of the mag is supposed to prevent scratching of paintwork. However, you will find the magnet attracts small particles of metal which are almost impossible to get rid of. For that reason, any magmount I use (and I've used lots over the years) is first planted onto thick polythene. At least any material that sticks to the underside of the polythene then falls off when you separate polythene from magnet. Not a perfect solution, but does help.
If you are going to fix the antenna to the rack, you may be better off finding a bracket that clamps to the rack - you'll very likely find the rack is grounded (dc wise) to the chassis at the bottom anyway.

Hmm...

a pair of short antenna one each rising from the sides of the luggage rack might look "interesting" and work well.

Thanks Graham and Peter for your superb insight into the problem.

I'm in the process of making a stainless steel bracket to attach to the luggage rack, to which the aerial will be mounted. Assuming that the luggage rack is a metal to metal connection with the chassis, this should give me an earth. If not I will just run a short ( hidden) lead from aerial to chassis.

Thanks again guys for your input...

Steve

Steve,

please let us all know how well this works: I'm about to follow in your footsteps!

If you still use the magmount I wouldn't worry too much about running an earth lead to chassis.
What's more important is that you have a piece of bodywork below to act as a groundplane.
Trying to find a suitable web site that explains things in an easy to understand fashion...

Thanks Graham, please explain when you have sussed it out. With aluminium bodywork I'm totally confused about the bodywork/ groundplane theory. My CSE woodwork never covered this subject!

Well, put simply, you really want a flat plane area under the aerial - like a car roof. Acts a bit like a mirror in extremely simplistic terms. Not too important what metal it is. At DAB frequencies to work best it wants to be a minimum of little over 0.3 metre radius to be most effective. Difficult to achieve, so just aim to get antenna above bodywork, rather than be screened as it is now on your parcel shelf.
Mobile antennas tend to be a bit of a compromise - you should see some of things we try for short wave bands!

Thanks Graham for the explanation,
back to the luggage rack utilising the rear bodywork as the "mirror" and see what happens.

Luckily it is not essential to drill any holes in the bodywork wherever I choose to position it!

Many thanks,
Steve

Steve

I have had a DAB radio fitted to my +4 for a couple of years using a screen mounted antenna.
The antenna I used has a small pre-amp box about 35mm sq and two very thin wires coming out horizontally.
I mounted the box behind the mirror mount and fitted the wires along the top of the screen.
Unit requires 12v which inmy case is fed up the coax from the radio.
I have found this arrangement works very well and does not need any body work drilling etc.
If I could find out how to add pics I could send one showing installation

Howard 2010 +4