Car Kits for Cellular Phones


Using a cellular phone while driving a car or track is very dangerous. Everybody who had a quarrel with his or her company knows how your concentration is lowered. If holding and using the phone is added your concentration on the traffic is totally gone. But a hands free carkit (carkit) has additional advantages. The phone is always fitted in the same position. There the battery is recharged while driving and the external antenna gives the best reception possible. If someone calls while driving the radio automatically mutes and the phone answers the call (if configured that way) after the first ring. If the microphone and the radio speakers are installed the right way the connection is usually good. Bad communication is usually caused by cheap carkits or wrong installation. After the call the connection is automatically terminated and the radio is demuted. The whole time the driver has not taken his hands off the wheel once. This is not only my opinion but also spoken law in ceveral european countries. Using the phone while driving without (and sometimes even with) carkit can get pretty expensive.


Country Penalty ca. in €
Austriafrom 50,-
Belgiquefrom 100,-
Croatiafrom 65,-
Czechfrom 38,-
Finlandup to 78,-
Francefrom 135,-
Great Britain³from 83,-
Greecefrom 50,-
Hungaryup to 105,-
Italy²from 150,-
Latviaup to 15,-
Lithuaniaup to 12,-
Luxemburgup to 74,-
Portugalfrom 120,-
Rumaniafrom 20,-
Spainfrom 200,-
Swenskanot forbidden
Dating: 05/2014
¹additionally one point in the German registry of traffic delicts
²cashed directly
³In case of accident with injury to persons up to lifelong prison

Car Kits

In 1994 I built a car kit for my NOKIA 2146 (PT-11) into my car and replaced it in 1999 by a model for my NOKIA 6150 which also could be used for a NOKIA 51x0, 61x0, 6210, 6310, 6310i, 7110 and 7210. The quality was quite good and I recommend only car kits from the original mobile phone manufacturer or from reliable brands like Funkwerk Dabendorf. These guarantee a high quality and other cheap kits are a lot worse according to my experience.


What is included in a typical "car kit"? Exemplarily I show the NOKIA CARK-91 but othermanufacturers have usually the same components as the functionality is always the same.

Nokia CARK-91

In the upper left area named MCC-1 is a holder for the cellular phone. The black box consisting of the whole electronics is named HFU-2. Additionally we need a microphone which is called HFM-8 here. The speaker is named HFS-12.

Installation Microphone

Now I built in the whole stuff into an Opel Corsa B. This is the small egg which was built in 1994. In Great Britain Opel is called Vauxhall. First we take place in the driver's seat and look around for a near position for the microphone. I saw two little plastic plates for the handle located on the co driver' site. Why do co drivers have such a handle anyway? Do I drive that bad :-)

Nokia CARK-91   Nokia CARK-91

The forward plate became my victim. Taken out we see a liitle plastic square with a stick on one side. I glued the delivered microphone onto this plastic square and pushed the cable through a hole drilled into it. Please make sure to point the microphone into the right direction - Your mouth!. Now the sophistivated craftsman spots the wonderfull color on the right photo. Wasn't the microphone black? Well, my girlfriend looked at me pretty strangely when I hustled in her stockings drawer and grabbed a fine one colored "Champaigne". Taken double and fixed with superglue over the plastic square and microphone it looks really great.

Installation Speaker

If you now think about how to install the speaker you don't need to. In the future you may use it for your walkman or diskman or so. For your car you better take the car radio speakers in the back. As the car kit mutes them while answering or starting a call this works great.

Installation Holder

Nokia CARK-91 Holder I placed the holder for the cellular phone between the front seats. Not the greatest place in terms of being visible but you should look on the road anyway and not on you phone's display! In my Corsa I wouldn't have found a place where it wouldn't have interfered with the co driver's airbag nor her knee. The whole thing has another advantage: If you forget the cellular phone in your car it is nearly invisible from the outside.

I placed a kind of screw with metal plate under the carpet through a hole at the right position. On top I just fixed it with a nut. Holds and looks great. At the place where the cables come out of the holder I made a slit into the carpet and directed the cables under the carpet targeting the dashboard.

Installation Antenna

A very important part for the function is a correctly installed antenna. I chose an inductive antenna glued from both sides on the windshield. I installed it over the rear-view mirror. One part has the antenna connector and is glued at the insde. At the outside the other part is glued at the same position. The transfer of the signal is done inductively. I used the delivered URM 76 Low Loss Cable which I had cut at an antenna specialist to the needed 2.30m and fitted with the right plug. It is a good idea not to save money here and neither do the cutting alone or leave unneeded cable uncut. Every centimeter cable and every connector mutes the signal. Usually 1m cable mutes about 1dB. The antenna cable disappears under the head lining in my car and is directed targeting the microphone on the left side of the car where it is directed downwards parallel to the microphone cable and connected with the cable coming out of the holder.

Installation Black Box

The cable coming out of the black box is also directed to the dashboard. I placed the black box behind the glove compartment after having taken it out. Somewhere a screw came out of the foam where I fixed the black box. Now I connected all the cables according to the manual. The car speakers have to be utilized with an additional parallel cable with a jack at the end identical to the delivered speaker from the car kit. Five cables come out of the black box. The blue cable IGNS (Ignition Sense) is connected to the plus contact of the battery which is only switched when the ignition is on. In my Opel Corsa the glove compartment light is just around the corner and I used it. The green cable AMC (Antenna Motor Control) can be ignored or do you have a motor driven cellular antenna? The yellow cable CRM (Car Radio Muting) has to be connected to the according contact of your car stereo. Check it's manual for details. I am friendly informed with "Mute" in the display during every call (my Philips even informed me of a "Call"). If you have a very old car stereo without muting functionality one could get this using a relay.

Installation Compenser

To improve the reception further I installed a Dual Band Compenser from Funkwerk Dabendorf. This unit compenses the muting caused by the antenna cable und if you connect it according to the manual there are exactly 2 watt for GSM 1800 and 8 watt for GSM 900 at the antenna. If you find out that the delivered 6m cable is way too long, on could use a shorter one. Every saved meter should give 1dB more power. This is not allowed according to the manual but works just fine. The Dual Band Compenser costs about € 150,- and is placed besides the black box in my car.