Adapting a Garmin Traffic Receiver to car antenna?

Garmin makes an "integrated" FM traffic info receiver for some models of GPS that allows connection to the car's AM/FM antenna. But not my model (Nuvi
660); I must use only the GTM20, a cigarette-lighter-powered model:
Benefits of using the car's antenna are mostly stealth: the cord-that-is-the-antenna between the cigarette lighter (which will be relocated inside the glove box) and the GPS plug that lays on the dashboard makes for an advertisement to crooks. And the car's antenna would, arguably, work better.
What are my options re. adapting the GTM20 to work with the car's antenna? Could this be as simple as splicing in a motorola antenna plug to the cable? Or...?
Ideas?
Thanks.
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All of these receivers have the Traffic FM receiver module embedded in the DC adapter, on inline on the power cable - https://buy.garmin.com/shop/shop.do?cID 3
AND - as per the manuals - some DO HAVE a special connector for an external antenna which in the manual appears to be located directly on the inline module...
In looking over this list - and actually downloading the manuals, it's hard to tell the difference between them - and the "18-pin flat plug" is for those special CRADLE mounts, while others are for the mini-USB on the GPS itself...
It is a bit confusing - even have the GTM-20 listed twice, but with different hardware features...
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As far as I could find, only the GTM10 is listed as requiring "professional installation" (ie, having capability of using the car antenna and/or power from other than the cigarette lighter):
<https://buy.garmin.com/shop/shop.do?pIDc95#accessoryTab
All others use some kind of cigarette-lighter power adapter and have it's own antenna.

It's the cradle-mount FM receiver / power adapter that is unique to the 660 and is found only in the GTM20.

In a conversation with Garmin tech support, I learned that there are 2 GTM-20 receivers: pn 010-00544-01 and pn 010-00544-13. The only difference is that the -13 comes with lifetime traffic service and the -01 comes with a trial service (6-months or 10 months -- both were offered).
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From what I can tell, the two parts that are labeled GTM-20 are also physically different. The original, with the 6/10 month trial, had a uniform cord between the 12 V plug and the GPS-side connector. The newer one, with the lifetime subscription, has a molded section near the GPS terminus which includes the receptacle for an external antenna connector.
--
Rich Webb Norfolk, VA

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A few days ago I picked up a Garmin NUVI 285WT for $100 from Amazon.com I was configuring it indoors and trying to activate the MSN traffic service 9 month trail. I could not get a good enough signal indoors so I connected a piece of coax to the wall jack leading to our outdoor TV antenna, put a jumper wire with an alligator clip on the inner wire of the coax and wrapped the jumper wire around the NUVI power cord (which includes the traffic receiver) and the signal strength increased to 100 percent, all bars lit green, allowing me to activate the traffic software. I wonder if a similar technique would work with a car radio antenna?
Steve
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wrote:

What is so goddamned difficult about simply buying a GPS antenna, which BTW, you retarded, overtly cross-posting twit, makes the device properly accurate?
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On 2/27/10, Bart! posted:

Because that's not what they are talking about. As stated in the posts and in the subject line, they are talking about the traffic receiver, which uses FM radio signals.
--
Gene Bloch 650.366.4267 lettersatblochg.com



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On Sat, 27 Feb 2010 15:59:49 -0800, Gene E. Bloch

You have to understand AlwaysWrong. He's *always* wrong.
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On Sat, 27 Feb 2010 19:49:11 -0600, krw wrote:

He posted a reply to my post about the same time you did. I am beginning to see what you mean.
Also, I hadn't looked at his headers before - a serious misstep on my part...
--
Gene E. Bloch letters0x40blochg0x2Ecom

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On Sat, 27 Feb 2010 15:59:49 -0800, Gene E. Bloch

Then, the device should have a separate antenna port.
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Bart! wrote:

It should but it does not. It plugs into the USB port on the back of the GPS. The USB port is used to data signal and power to recharge the built in battery.
the cable is wired like this
12 VDC power plug,
A couple of inches of DC power cord to an approx. 2 inch oblong FM receiver
From the FM receiver 2 cables go to the GPS USB port, one is data/power, the other is used as a broadcast band FM antenna , hanging inside your car.
Hacking the assembly would require cracking open the sealed FM receiver without damaging the device, figuring out where the antenna wire input is located, and soldering in an antenna input jack and an A/B switch , sealing up the unit (voiding any warranty).
Do you suggest I put the device in my shop vice, apply pressure till it cracks open or turns to shrapnel, or dig out the dremel tool?
I prefer inductive coupling to hacking a device still under warranty.
Steve 73 de N2UBP
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wrote:

I prefer contacting the manufacturer to guesswork.
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If you'd followed the thread you would know that the manufacturer has been singularly unhelpful/useless - thus the need to draw on the collective wisdom of the group. Look and think before you jump in, and try to contirubute courteously.
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Bart! wrote:

Bart, you old fart.....
This is not a GPS frequency. Traffic data is piggy backed on broadcast band FM frequencies. An external GPS antenna won't do squat to fix this issue.
You need more fiber in your diet. Have a nice day!
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wrote:

You must be new here. This month the kill-file log shows that he is using the following aliases, sorted by number of entries. Better to just ignore him. Don't feed the trolls and all that...
1: VioletaPachydermata
2: TralfamadoranJetPilot
3: " snipped-for-privacy@thebarattheendoftheuniverse.org"
8: Lil Red Riding In The Hood
8: TheJoker
21: "Herbert John \"Jackie\" Gleason"
--
Rich Webb Norfolk, VA

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On Sun, 28 Feb 2010 16:19:58 -0500, Rich Webb

You're a goddamned liar, boy. I haven't used half of those, so your precious filter must be catching others' responses as well.
You really are about as retarded as it gets, bub.
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Rich Webb wrote:

Here is a list, in alphabetical order.
THE DIMBULB SCORECARD
Chieftain of the Carpet Crawlers
GoldIntermetallicEmbrittlement
Lil Red Riding In The Hood
snipped-for-privacy@thebarattheendoftheuniverse.org
scorpius
SomeKindOfWonderful
Sum Ting Wong
The Great Attractor
The Keeper of the Key to The Locks
snipped-for-privacy@thebarattheendoftheuniverse.org
--
Greed is the root of all eBay.

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On Sun, 28 Feb 2010 20:26:57 -0500, "Michael A. Terrell"

That is not what he listed, dumbfucktard.
His list was supposedly those I used last month.
The problem is that he is almost as full of shit as you are, if that is even possible.
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On Sun, 28 Feb 2010 20:26:57 -0500, "Michael A. Terrell"

The numeric would be at the front of the list, idiot.
You cannot even get something so simple as alphabetization right!
Bwuahahahahahahahahahahahahahahahahha!
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