Adding external antenna to c340


Would adding an External antenna help my
reception a great deal. I have experienced signal
loss a few times but it's not common. This normally
happens when I'm in a big city with lots of tall
buildings. Since my C340 doesn't have a high gain
SiRF chip Antenna like the c500's and Nuvi's, would
adding an External antenna solve my problem?

See also


external antenna

The SiRF chip in my TomTom works pretty well. I haven't tried an external antenna with any of my older Garmin models to compare performance.

Would you put the antenna outside your vehicle? If not, would its view of the sky be any better than where your GPS is located?

... seems like there are a lot of variables that might affect your results. smile


External location

Well, currently my c340 is located an inch or two above my dash in the center of the windshield. It's a very good location for a signal. If I were to mount an external antenna, I would place it outside the car towards the middle rear of my trunk, basically right where it closes near the glass. I'm thinking it would help but I'm not sure if if would be significant enough to spend the extra money. I was looking at the one they sell on the Garmin site for 30.00 dollars. Do you know if they are prone to scratching paint..... Thanks JM for your help.


The downside of an external antenna

I traveled a lot with my eMap as my guide. It was/is a pretty good device. The mount I devised had the unit positioned too far from the windshield, though, so I bought a 3rd-party external antenna. The performance improved.

Now I have a c320 positioned well within the huge span of a Prius windshield. I experimented with transplanting the eMap's external antenna to the c320 and saw no difference. What I did see, however, was that the external antenna was a real nuisance when I wanted to detach the c320 from its mount for security purposes. It meant detaching and re-attaching the antenna with the fussy, vulnerable connector.

Garmin was brilliant in feeding the GPS receiver's power through its mount. They could have done the same with the antenna but chose not to do it. There might have been an impedance-matching issue.

To your other question, I've had no problem with scratching the paint. The antenna's lower surface is a tough, smooth plastic membrane.

Maddy's pal, retired geek

Where do you...

Where do you attach the antenna? You mentioned scratching the paint - What does that mean? I would love to improve my reception but didn't think it could be done. Can you explain how to do it?


I use an external antenna

I use an external antenna with my c340 and found that aquiring satelites is much quicker and no more "Lost Satelite Reception" notices from "Karen". On a recent trip from Florida back to Canada (without the antenna) I lost reception briefly quite a few times but not since I put the antenna on. My c340 is mounted low between the seats so the antenna really boosts the signal and I haven't found that the magnetic base has marked the roof of the truck at all. I also got the "straight on" connector rather than the 90 degree connector and it's very easy to plug in and out of the Garmin.

Garmin c340

i use it too

I just got one too. It does suck to take the gps unit off the base when you leave the car. Other than that i like it because I like to keep the unit low in case it falls from its base. They are not that expenisive but are a mess to work with. If the plug could plug into the base then it would be a ton better.

External antenna

The external antenna is great ! faster response times.


I added an external antenna

I added an external antenna to my C340 on the recommendations in this forum. First I tried it on my Emap. My jaw dropped as I saw it picking up satellites in my kitchen! How could that be? Then I plugged it into my C340 and it acquired sats in my kitchen. I moved around through my house and it lost reception in some places. Wow. I tried it in my car under normal use outdoors and it acquires the sats almost instantly. I am amazed that the antenna could make that much difference.

Garmin Emap, Garmin C340, Garmin Nuvi650


I agree with Lokall - I use the window suction mount when I'm on a loooonnng distance trip with my SP C330. I put the suction cup up as high as I can and I do get some minor problems with reception! I use the external antenna and get very FAST updates and practically no signal fadeouts ! Except in tunnels of course and in deep mountain passes . (depending on which way the pass is running) Locally I just use the Spider dashboard mount without an external since there "ain't" too many mountain passes here in Flor-i-duh !
I just run the cable on top of windshield shade and out passenger side door and place in center of roof - making sure cable is tightly against metal !
But my unit is "Lila"

MrKenFL- "Money can't buy you happiness .. But it does bring you a more pleasant form of misery." NUVI 260, Nuvi 1490LMT & Nuvi 2595LMT all with 2014.4 maps !

Where to connect the external antenna?

I have a SP c340. Where do I plug or connect the antenna to the unit? Is it on the unit's back side to the right of the serial number sticker? I just don't want to buy one to find out it doesn't work.

On the 530 it is on the

On the 530 it is on the lower lefthand side of the GPSr. It has a little rubber cover on it.

Charley - Nuvi 350 - Bel STI Driver - Cobra 29 w/ wilson 1000 - AIM: asianfire -

Adding external antenna to c340

I recently bought an external antenna for my C330. I didn't see any increase in the speed of acquiring signals. I have the antenna on the roof of my pickup, running the line through the door inside the weather molding and under the floor mat by the front of the passenger seat.. I have a satellite radio antenna mounted the same way on the opposite side of my truck. It works just fine.

Not doing anything worth a darn.

External Antenna

I have an external antenna that i got from ebay (55dbs). Its mounted near the rearview mirror. so far it seems to take just as long or longer to acquire satellites. I can't see any gain.

So it is a Ford or Chevy

So it is a Ford or Chevy question?????? LOL.

Charley - Nuvi 350 - Bel STI Driver - Cobra 29 w/ wilson 1000 - AIM: asianfire -