FM Transmitter - Nuvi 660

I just bought my first GPS, a nüvi 660, and have only started to play around with it. My 1st issue was the FM transmitter, which is how I found this great web site. My vehicle has the 6" radio antenna located at the back, on the roof (SUV). The nüvi's FM signal could not reach it for all the sheet metal. I barely heard the audio under all the static.

I took the advice from an earlier posting in this topic and bought one of the Sony cassette adapters at Best Buy. In just the little bit of time I've had to listen to it, it sounds great! So far, I haven't heard the "clicking" talked about in an earlier post. It even was a great help with the audio from my bluetooth cell phone.

I'll keep searching your web site to see what else I can learn, but thanks for the help, so far.

Glad to hear the Sony Cassette adapter works for you Gary. The problem for me, I believe, has more to do with the low quality of my Chrysler cassette deck than anything else. Sound quality on playing cassettes is poorer than the FM radio. And the adapters just don't line up correctly in it.

I've tried removing the FM antenna and that worked well with the FM transmitter. So I'm thinking about installing an in-line switch in the antenna line so I can leave the antenna in place and still listen to the radio when not using the GPS.

I fixed my transmission problem by improving the ground plane on the GPS as follows:

I took a yellow 1/8" mono to RCA jack cable that came with a portable DVD and simply cut the tip off of the 1/8" jack, plugged it in, and cut off the RCA jack so about 2' of wire dangles. My installation went from totally unusable to great. PS-the color of the cable does not matter, however the fact that it is a shielded video cable may have some bearing on how well it works.

Some background: I noticed the 660 transmitter works great when the unit is in the house plugged into a wall outlet. It transmits clearly over 15 feet to my home stereo so the transmitter has enough power. However when I unplug the unit from the well, I have to hold the unit about 1 foot from the stereo to pick anything up. I believe the issue is lack of adequate ground plane for the GPS FM transmitter to be effective. I measured the resistance on the car charger and found that the GPS ground and Car grounds are isolated. Garmin take note - there is probably a quick fix in connecting the grounds in the suction mount, possibly through a capacitor to eliminate other noise. There may be some other fixes but this is a quickie that works well.

Steve
I just followed your lead and going to give it a shot. We are going on a 6 hour road trip next weekend and through many radio station zones.
I cut off the tip as you have suggested and left the other end blank (had a cable with 1/8" jack each end). By plugging it in I take it that you mean the ear phone jack on the nuvi
I tried the ear bud trick and it works somewhat but still leaves room to test other ideas

Thanks for the suggestion

This is definitely YMMV since the FM stations in the area are different. The manual on my 750 says to use lower channels, I think 90.5 and down.

When you get out of town with fewer stations it is much better but you may have to adjust to another channel as you get to an area with a conflict.

My Volvo has a retractable radio antenna so that takes care of the interference for me.

Folks,

Does anybody know a way to be listening to a radio station and have the NUVI interrupt it when it needs to tell me to make a turn?

Thanks!

Nope. You can't do that.

Without additional equipment.

In addition to the Nuvi, you'd need a mixer, and something to act as your programming source.

You would take the Nuvi, plug it into one input on the mixer, and take your program source - like a mp3 player, radio receiver, XM or Sirius receiver - and plug that into another input on the mixer. The mixer's output would then go into your car's audio system, either through an aux input if equipped with one, or, a transmitter that would send the combined signals to your car radio.

There was a previous post that suggested an unusual aux port that can be added. The unusual feature when I checked on it was that it had two ports and one provided a priority status. If I understood correctly, when a signal was present on that port, it would interrupt the other source. Wish I could think of an easy way to search for it -- the priority port was not mentioned in the post.

A poor man's version of this is to record the radio broadcast and put it on the SC card. Navigation interrupts mp3 player just like you want. Not sure of the nature of the radio you want, but maybe it is available as a podcast.

http://www.mixitproducts.com

Yep -- I thought it had been you, but since you didn't mention it this time, I decided to dig it up. By the time I did, and found it WAS you, you had already provided the url. Interesting product BTW.

I don't have one (yet...) - still trying to decide if I want to spring for XM or Sirius. When I do that, I'll likely get one.

Very soon, Keith, you will spring for Satellite radio, as XM and Sirius are merging. Personally, I'm against the merger, because as an XM subscriber, I'll have to subsidize (sp) the outragous salary of the filthy mounted howard stern! As I understand it, the merged company will offer "packages". I love satellite radio, but will have to look over their merged packages to determine if I want to continue as a subscriber.

Cheers.......... Joel

Did you mean to say this?

Nope - meant to say "mouthed".... Thanks for the catch! My eyeteeth got in the way of my qwerty keyboard.........

Joel

I have read on different forums about the problem with the terrible FM transmitter on the Garmin nuvi (I have the 680 model). Unfortunately I didn’t do any investigating before I spent the extra for a model with this lame feature. I tried one of the suggestions someone had about resetting the country of origin to a country which may allow a higher transmitter output. This did not work for me; perhaps that person had a different rev. of software which actually changed the power output.
I did read that you could go into a diagnostic mode and actually change the output power but unfortunately you can not save the changed setting. I used this very useful tactic to determine if I could find out what changed in the transmitter section when the different power settings were engaged. After much tinkering I found that by lifting pin 4 of the IC marked BHTX or pin 6 of the IC marked S79 (same electrical connection) it would transmit at a higher power. I hope this helps those of you who do not like listening to hissing with your music. I tried to include a picture of the IC layout but have not figured out how to do that here. I don't know if this modification will cause any detrimental effects to the FM transmitter but if it totally destroys it, I’ll call it a model 650. Remember your warranty is garbage if they can determine that you 'went in'.

Hi, everyone,

I have the same poor performance with my FM transmitter. One earlier post suggested that the power output of Nuvi's FM transmitter was variable. Garmin techs say "NO". There ARE FM transmitters out there with enough power to work reliably in most locations. As an example, my son has a satellite radio reciever with a transmitter. He claims that his never fails. An associate at Radio Shack assured me that he could sell me transmitter that would work, "no matter what". All I had to do was plug it into the earphone jack on my Nuvi. I haven't done this because this feature isn't that important to me, but I do understand folks expecting it to work reliably after they paid extra for it.

Miki

So you actually did a hardware hack on your nuvi? That's pretty cool. No detrimental effects to any functions?

Right now I'm using the FM transmitter with my car's antenna wire unplugged to avoid interference. It still hisses unless the power cable is in exactly the right position.

I think I'm going to install a proper wired FM Modulator (Scosche FM-MOD02) in my car sometime this summer. I think it would be less work than your hack, at least for me - and still cheaper than upgrading my car's stereo. Plus I can keep the "stock look" of the factory stereo.

This sounds pretty cool, let us know how it works!

Maybe some good news for us troubled Nüvi 760 users.
FM power definitely needs some boost.
The Audio Output Test Page clearly provides a High Pwr option, but seems it cannot be saved for normal use.
Here goes a hack that has worked at least for two 760s tried.
There is no locale restriction as to this hack, as it has been tested on United States locale succesfully, as on my own (Espa).
To make this hack operational some unit might need a factory default. Not needed in my units, except for the need to try the hack with USA locale.
Factory default is accessed by pressing the screen down and to the left while powering up. Some seconds after the "Do you really want to erase all user data?" question shows up.
No need to erase user data, anyway.
So this is what I did:
- United States locale selected
- American English language selected
- US-Central time zone selected
- Touch the Volume icon and fully enable the FM transmitter in case it hasn't been done before, as after a factory default procedure
- Touch on the battery icon for some 10 seconds
- "SW ver 4.80 nuvi 760 S3 M V3 iNAND2 2GB" is read top of screen
- Touch Next, Next, Next an once more Next.
- Now on the "Audio Output Test Page" select FM checkbox
- Touch Up in FM Property Value - select your preferred FM channel, or none at this point (not relevant)
- Select checkbox High Pwr
- FM Stereo, Audio Cmpr and Audio Lmtr are also selected, but from the defaults - if unselected, FM hasn't been enabled for the unit
- If now FM power checkbox (on the left) is selected, 115 dB is read - previous value was 100 dB
- Touch Back - w'ere in Audio Test Page
- Touch Aud V
- Select 0:/Garmin/Voice/Afrikaans___.vpm: 2.00
- Touch Back
- Touch Down and select TIS TRAFFIC URG
- Touch Play Phrase - the unit powers off
- Power up, got to the (as previously stated)"Audio Output Test Page" if you were usnure of the satus of your Nüvi - FM Power reads 115 dB and the High Pwr checkbox have been retained

Hope this little hack helps save us trouble from dissassembling and/or phisically hacking our Nüvis.

Greetings from Buenos Aires.

When I really want the audio output, I connect the aux audio (earphone) jack to my car stereo. Cassette tape adapter in mine, "aux audio" in newer cars.

Garmin built in FM transmitter is weak and not effective, if you hold the unit then your radio will get more signal (you become the antenna). Otherwise use the mini to RCA cable or mini to tape.

fulanopio - the problem is that this change does NOT stick if you are actually in the US. When you turn your gps on in the US the gps recognizes the US coordinates and turns the FM power back down to 100db. Other folks have tried to get the power to stay at 115db and it simply doesn't work.

use a stereo jack or one of those cassette adapters if you have an audio out on your GPS it works way better than fm

Yes, that's true... This is what I did too (stereo jack) and works WAY better than anything else --believe me!

Never any kind of interference from a strong-nearby radio station, either. - - -

There were absolutely no changes to any other functions that I use. I should point out that I do not use the blue tooth function. The MSN feature uses the power cord for an antenna so they are not using the same circuit. If there is a problem, simply soldering the pin down will remove the mod. I was able to upload pictures on other sites. I don’t know if I should mention other sites here but if you do a search on ‘lzep fm transmitter’, you will run into them. I also uploaded some spectrum analyzer plots of the output compared to an off the shelf unit.

I think you can mention other (relevant) sites here, I've seen others do so-

i noticed that if you take a nuvi 680 out of the cradle and hold the left side of the gps up next to something metal in the car , the transmitter worgs really well , for example i held the left side of the gps up to the stearing wheel and the transmitter workd great. I havent had time to expieriment more , but i am guessing that if you were to take some small guage wire and tape or otherwise attatch it to the left side of the nuvi and string it across your dash or attach the other end to a metal object in the vehicle it might be the improvement everyone is looking for . i wil be trying this when i get some time and will post what i find

absolutely

Wow, I read through this entire string and I still don't see a 100% solution except for buying a new radio or a new car. I guess we just have to tolerate the occassional static.

tried taping a piece of wire to the left side of a nuvi 680 today on a trip into cleveland , and i must say the results were pretty good , not 100% but i would say a good 90% improvement. i cut a piece of 18 guage insulated wire about 2 feet long and taped one end to the left side of the gps and just layed the loose wire up on the dash and it made a remarkable improvement. very little static , i played a few mp3's from the gps and it sounded really good . going to try a couple of other ideas and ill post my results .

Hi, I am new around here. This site is great. Anyway, I use my nuvi 750 on my motorcycle and it comes through the radio loud and clear. I thought I might have a problem on the bike with electrical interference and such, but not at all.

I tried wrapping the wire all the way around mine, a few good wraps... and it did not help any.

What finally worked, was to take a short cable with a earphone-jack at one end, and two RCA-jacks at the other end, and patch the Nuvi directly into an audio-input in the rear of the stereo head-unit.

So... now I have a wire which comes out from under the dash, and I have to plug it into the earphone-jack of my Nuvi. Plugging into my Nuvi was unavoidable... but works quite well-

I too was hoping to avoid plugging wires into my Nuvi, but at least I have a good working GPS-audio to car-stereo relationship now.

NO static ---ever---

I tried it last year when I first got the 660, it didn't work at all. My expectations were low as I've tried iPod adapters that used the FM transmitters and the music wasn't good, but the Nuvi surprised me by being far worse!

My Nuvi doesn't have the FM transmitter but the cassette adapter I bought off Amazon work quite well.

Ok i tried my second idea with great results , i took a piece of about 20 guage wire and taped it around the 680 i started on the left side of the nuvi and went only 98% around leaving a small gap. so it was not several wraps , and not quite one full wrap . More is not always better as different wavelengths are different lengths. i had full quieting sound even as i drove through a area with several high power broadcast antennas. if anyone can provide a place to post a pic i will gladly take a pic and make it available for others to try .

Free photo hosting here: http://www.tinypic.com/

I will get a picture posted this weekend

Ok here are 3 pics of the wire attached around the nuvi , my next expierament is going to try a smaller wire, small enough that it can be down in the seam around the nuvi , when i get to that point i will see if there is interest in those results and pics.

Pic 1 - http://i25.tinypic.com/28iurkp.jpg
Pic 2 - http://i27.tinypic.com/339t7ns.jpg
Pic 3 - http://i25.tinypic.com/71jwhz.jpg

Thanks for posting the pix, they are good shots... but it does not look as though your wire (partially wrapped and then taped) connects to anything, as in being run to a connection with your car-sterio, or something.

How is this able to help? Was there a -before & after- kind of improvment because of that wire?

That is fabulous! How did you know about it? Are you at liberty to say?

Unfortunately this doesn't work on my Nuvi 750--power reverts to 96dB no matter what, even with factory defaults. I don't know of any hardware hacks for this model either.

Any ideas for the Nuvi 750? Thanks!!