Nokia 6120 car kit causing radio interference

Submitted: Monday, Feb 04, 2008 at 11:42
ThreadID: 54217 Views:4251 Replies:8 FollowUps:6
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I have just had a Nokia 15W car kit with a Force cradle (for the antenna connection) installed for my Nokia 6120. The phone and car kit work really well (I have not tried the 6120 in the bush yet for range). When the phone is in my pocket, or anywhere in the vehicle, the bluetooth connection works.

My problem is when I place the phone in the cradle, there is severe interference to the FM radio. If I place my hand over the phone (over where the phone antenna is located) the interference is reduced.
It would seem obvious the interference is caused by bluetooth, but why only when the phone is in the cradle???
Any suggestions??? The installer did not have any.
Cheers, Dalb

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Reply By: stocky - Monday, Feb 04, 2008 at 12:20

Monday, Feb 04, 2008 at 12:20
stupid force cradle is only a "coupler" and probably a badly tuned one at that - simply its picking up the radiated signal from the phone and causing that to be transferred to the radio via wiring etc.

move the antenna wire running to the cradle - or get better coax for the antenna - many cheap antennas have crappy coax - not sure what antenna you have. also where is antenna on car in relation to FM radio antenna??
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Reply By: Steve from Top End Explorer Tours - Monday, Feb 04, 2008 at 12:23

Monday, Feb 04, 2008 at 12:23
It is purely and simply Telstra's fault just ask Daveo.

ROTFLMAO

Cheers Steve.
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Follow Up By: Member - Doug T (FNQ) - Monday, Feb 04, 2008 at 12:41

Monday, Feb 04, 2008 at 12:41
ROTC LMAO just to be different....



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Reply By: Sand Man (SA) - Monday, Feb 04, 2008 at 15:31

Monday, Feb 04, 2008 at 15:31
Dalb,

This is an unusual interference symptom I have not seen before.

There is/was an issue with the 6120 causing echo at the remote end when using a car kit, but that has been resolved with a firmware upgrade now available.

If you haven't done so already, I would suggest downloading the "phone updater" application from the Nokia site and upgrading to the latest release.

Bluetooth should not cause any interference to FM radio.
Maybe search the Nokia forum for any similar incidents, particularly with the 15W car kit.

I use the CK-7W car kit, which also uses bluetooth to interface with the 6120 and I also have the Force Technology cradle.
As the force cradle does not physically connect to the car kit I don't think this is the cause of your problem.

Another thing you can try is to unplug the cradle's power plug from the ciggy socket and see if you still get the same effect, or disconnect the external antenna connection, if you have one.

It is a process of elimination sometimes.
Failing all the above I'd go back to the installer and demand further investigation. Maybe it's peculiar to the 15W car kit.

Bill


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Follow Up By: Member - Dalb (SA) - Monday, Feb 04, 2008 at 15:54

Monday, Feb 04, 2008 at 15:54
thanks to all of you for your responses...

I forgot to mention that I did the nokia 6120 upgrade before the car kit was installed (to try to stop another problem with the screen regularly going fuzzy and unreadable).
The interference is only caused when the phone is in the cradle, but there is no interference even when the phone is held next to the cradle.
The unit is currently installed in a Falcon (will tsfer it later to the LC100). The Falcon does have the radio ant in the back window and, the phone ant is attached to the back window - but this has never been a problem before with CDMA.
The problem is perhaps most likely to be the Force cradle combined with the bluetooth signal somehow, so i will try moving the wiring around and then look at the ant coax cable etc
The cradle is hard wired, instead of using cig lighter, and yes the charger does charge the phone - so perhaps i should talk to Force.

many thanks, Dalb
Cheers, Dalb

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Follow Up By: Sand Man (SA) - Monday, Feb 04, 2008 at 16:08

Monday, Feb 04, 2008 at 16:08
Dalb,

Maybe you have a crook inductive coupler on the cradle.
Perhaps try another cradle to see if the problems persists, or disappears.

Bill


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Reply By: JustT - Monday, Feb 04, 2008 at 15:33

Monday, Feb 04, 2008 at 15:33
I've noticed that some Nokia phone car chargers cause interference with radio, does the cradle also charge the phone?

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Follow Up By: Member - Crazy Dog (QLD) - Monday, Feb 04, 2008 at 16:27

Monday, Feb 04, 2008 at 16:27
I think you will find that this is caused by the DEBOHIT effect..


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Reply By: stocky - Monday, Feb 04, 2008 at 16:34

Monday, Feb 04, 2008 at 16:34
that may be it - the crappy force cradles need a seperate power supply - usually provided by $2 ciggy light lead adaptor thingy.

If you have that type - unplug the ciggy lead and see if it goes away

Those leads have nasty switchmode power supplys in them - lots of EMI!
AnswerID: 285557

Reply By: Member - Olcoolone (S.A) - Monday, Feb 04, 2008 at 17:40

Monday, Feb 04, 2008 at 17:40
We use the Force cradels and have not got a problem, it maybe to do with the passive antenna coupling being close to the radio.

1) If you have the phone in the cradle with bluetooth turn off does it still do it.

2) Does it only do it when you are talking on the phone.

3) If you disconnect the power from the cradle with the phone still in the cradle does it stop the interferance.

4) If you have the phone causing interferance in the car kit does it still happen when the phone is behind or near the car cradle or radio.

The power source is through the car kit.

It's good to see people blaiming Force for the problem, Force only makes the cradle the rest is Nokia.

When the phone is in the cradle and causing interferance grab some tin foil and a lenght of wire, rap the foil around the back of the cradle. Connect the wire to the car body earth point and with the other end of the wire touch it on the tin foil...does the noise go away.

Regards Richard
AnswerID: 285575

Follow Up By: stocky - Monday, Feb 04, 2008 at 21:30

Monday, Feb 04, 2008 at 21:30
The std force cradle doesnt get its power from the car kit - it gets it from a ciggy lead.....
:-)
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Reply By: Member - Olcoolone (S.A) - Monday, Feb 04, 2008 at 22:45

Monday, Feb 04, 2008 at 22:45
Opps sorry we have the Nokia CW7 car kits, they come with a charge cable that plugs into the bottom of the Force cradle and then into the Nokia Bluetooth car kit.

AnswerID: 285679

Reply By: SimonInAustralia - Tuesday, Feb 05, 2008 at 21:19

Tuesday, Feb 05, 2008 at 21:19
I have just ordered a Force cradle for my Nokia 6120.

What is the best antenna to use with this?

Thanks.
AnswerID: 285842

Follow Up By: Member - Dalb (SA) - Wednesday, Feb 06, 2008 at 09:50

Wednesday, Feb 06, 2008 at 09:50
Simon

Sorry, I know nothing about antenna's. The installer of the car kit just connected to the existing antenna I had for the CDMA. But when I ordered the Force cradle I was told that any type of antenna will work including a broomstick type.
By all forum discussions I have seen, the most important thing about antenna performance (phone or UHF etc) is clearance above and around your vehicle - for instance even a metre or so long broomstick type where the tip is lower than the roof/packrack/van etc may not be a good as a little 4" floppy one that is say on top of your packrack with no obstructions in any direction.

Thanks to all the others who have contributed advice. I have not solved the problem yet, but will post a new thread later to, hopefully, let eveyone know how it was resolved.


Cheers, Dalb
Cheers, Dalb

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