Aftermarket Radio - no AM readio reception?

[Paul & Wendy]

Hi All,
I have just removed the standard 6 disk controller head unit in my wife's 2003 Cabrio and fitted an after market head unit to give my ipod control. Everything works fine, including FM radio reception, but there is now no AM radio reception.
I had presumed that the standard aerial / antenna cable gave both FM and AM reception from the antenna wires location in the front windscreen, but am now wondering whether the AM antenna reception was included in the separate CD multi plug that is no longer in use.
Any suggestions or comments would be appreciated.
Cheers, Paul

[Zann]

What brand is the radio?

Aftermarket radios tend to focus 99% on FM quality and 1% on AM so generally you will not get as good a reception on AM going aftermarket.

Fancy features, 1000 LED colors, style, etc tend to drive the market whereas the simplistic factory radios are held to a higher standard when it comes to reception and ease of use to help close a sale and not lose a sale. Same reason the aftermarket doesn't put huge ass buttons on their radios like factory.

[MyOtherRidesAVette]

Originally Posted by Paul & Wendy

Hi All,
I have just removed the standard 6 disk controller head unit in my wife's 2003 Cabrio and fitted an after market head unit to give my ipod control. Everything works fine, including FM radio reception, but there is now no AM radio reception.
I had presumed that the standard aerial / antenna cable gave both FM and AM reception from the antenna wires location in the front windscreen, but am now wondering whether the AM antenna reception was included in the separate CD multi plug that is no longer in use.
Any suggestions or comments would be appreciated.
Cheers, Paul

Hi Paul,

Probably a little bit getting lost in the translation here! (lol). I think you have a 2003 NBC, called a "cabrio" in other countries, but no matter. And when you say front windscreen, I know you are speaking of the windshield. Yes, the antenna in the windshield is designed for FM reception, that is why the two imbedded leads rise together and then run in opposite directions, actually even to an engineered length. Has to do with FM radio frequency wave lengths. AM reception is taken from either here or another wire serving the radio.

I believe the CD multiplug you are referring to would be the harness for the remote 6cd changer that the vehicle did come wired for regardless of whether or not it had the actual unit. And yes it is possible the factory head unit was using one of these wires as the AM antenna.

A factory head unit wiring schematic may address this, but I wouldn't bet on it.

Your aftermarket unit should address AM antenna in it's installation instructions.

MORAV

[Audiomechanic]

I've never seen a Beetle without the little nub antenna on the back of the roof. Never seen one with the antenna running around the windshield.

You can try one of these:
Amazon.com: Scosche Vwa-2B Volkswagen Amplified Antenna Adapter: Electronics

I added that to my aftermarket radio install and the AM reception is now better than it ever was stock. It's clear all over town.

[MyOtherRidesAVette]

Originally Posted by Audiomechanic

I've never seen a Beetle without the little nub antenna on the back of the roof. Never seen one with the antenna running around the windshield.

You can try one of these:
Amazon.com: Scosche Vwa-2B Volkswagen Amplified Antenna Adapter: Electronics

I added that to my aftermarket radio install and the AM reception is now better than it ever was stock. It's clear all over town.

Any NBC! No roof, remember?

[Audiomechanic]

Uh...oh yeah. Forgot about those.

*face palm*

[MyOtherRidesAVette]

But the amplified adapter MIGHT be the solution if the external antenna is what the AM signal is being received by. Although, as the windshield antenna IS the optimum antenna for FM it might deplete its' effectiveness.

MORAV

[Audiomechanic]

I can check the wiring diagram in my Bently's when I get home for NBC's and see if it has a separate AM antenna. I want to say I doubt it does, but I'll check for sure.

Far as the amp helping or not, it's 13 bucks. Only one way to find out!

[Zann]

I seriously don't see VW going through the trouble of making some off the wall separate antenna for a seldom used AM band.

The window strip antennas are inferior to begin with and then add a possibly shoddy aftermarket AM tuner and you have your answer.

People typically don't upgrade to a aftermarket radio to jam out on AM talk radio and that's why the aftermarket manufacturers don't spend a dime on ensuring premium AM reception.

In all my years in the car stereo business I never had a customer tell me he wanted that head unit, amp and subs to rock out to Rush or Clark Howard

[MyOtherRidesAVette]

Originally Posted by Audiomechanic

I can check the wiring diagram in my Bently's when I get home for NBC's and see if it has a separate AM antenna. I want to say I doubt it does, but I'll check for sure.

Far as the amp helping or not, it's 13 bucks. Only one way to find out!

Wouldn't matter NB or NBC, same head unit. A lot of times radios use a small guage wire as an AM antenna (I know I have owned audio systems with separate AM/FM signal antennae input). Usually low wattage transmitters, hence short range signals in the US, today. The 50,000w Power AM Stations of days of old are gone. And most of the AM stations that are still around, for what ever reason, have sister FM stations. Well, except for our local Talk Radio (lol). Without a schematic of the radio head itself it may not be determinable from the Bentley.

And the OPer is in Australia so it might be a bit more than the selling price, I saw it was free shipping, but maybe different if International, if they even ship! Don't use Amazon, and didn't read further.

MORAV

[MyOtherRidesAVette]

Originally Posted by Zann

I seriously don't see VW going through the trouble of making some off the wall separate antenna for a seldom used AM band.

The window strip antennas are inferior to begin with and then add a possibly shoddy aftermarket AM tuner and you have your answer.

People typically don't upgrade to a aftermarket radio to jam out on AM talk radio and that's why the aftermarket manufacturers don't spend a dime on ensuring premium AM reception.

In all my years in the car stereo business I never had a customer tell me he wanted that head unit, amp and subs to rock out to Rush or Clark Howard

I'll agree with the lack of probability of two antennae. I won't speak to your stated "inferiority" of windshield embedded FM antennae. I'm sure your right about AM attentiveness in aftermarket, and be careful buddy, I listen to Rush and Clark! Think that gives you a 50%? dbl

MORAV

[Paul & Wendy]

Hi,
Thanks for all the replies - yes, probably caused some confusion with translations....I'm originally from Scotland, been living in Australia for 3 years and know that most of the posters on here are in the US. I guess that the car is NBC in the US, cabrio here in Oz, and a convertible in the UK.
Anyway, every other head unit that I have replaced has had both FM and AM reception via a single coax style cable from a single aerial / antenna - this is the first time I've ever had any issues. Have had wind shield style antenna before such as in my old Landrover Discovery that did not have any issues. The new head unit is a Pioneer and there is no separate AM connection. I have connected the power feed from the unit to what I'm guessing is a built in amplifier for the antenna.
May have to do without my fix of sensible talk on AM for music on FM.
Thanks anyway for the replies.
Cheers, Paul

[sb_beetle]

VW's are notorious for bad AM reception with aftermarket. You need to get an inline powered antenna adapter (bridges between the unit and antenna line with a power lead). Any electronics or car stereo shop should carry one for you. I've had similar issue with both a 98' Jetta/Bora and NB/Cabrio and aftermarket units and this solved it :-)

[MyOtherRidesAVette]

Originally Posted by sb_beetle

VW's are notorious for bad AM reception with aftermarket. You need to get an inline powered antenna adapter (bridges between the unit and antenna line with a power lead). Any electronics or car stereo shop should carry one for you. I've had similar issue with both a 98' Jetta/Bora and NB/Cabrio and aftermarket units and this solved it :-)

Excellent info. I hope they see it. And it's not just VW. Antennae today are designed for optimum FM reception, even in OEM units. Most ppl don't know but there is even an optimum length for the mast. Not a need for AM anymore except if construction zones which only use enough wattage output to broadcast a couple miles anyway.

MORAV

[Zann]

Originally Posted by MyOtherRidesAVette

Excellent info. I hope they see it. And it's not just VW. Antennae today are designed for optimum FM reception, even in OEM units. Most ppl don't know but there is even an optimum length for the mast. Not a need for AM anymore except if construction zones which only use enough wattage output to broadcast a couple miles anyway.

MORAV

Optimal length has more to do with transmitting than receiving but it is true that auto antennas are designed for the FM radio band with no regard to the lower AM band.

AM is so quirky with the shape of the car, routing of the antenna cable, etc which is why its an obsolete form of radio transmission.

As a fun fact, in the five years I spent working with Motorola, 99.9% of the government and private companies all used FM which is pretty much FCC required at this point due to limited frequency space. Only AM radios I came across were HAM, CB, and military (due to better range in combat zones and noticeable when you see a Humvee with a 102 inch whip tied down to the hood).

[slpopp]

I know this is a little late, but you could also have an antenna amplifier that has shorted out.

Was the AM working (the same day) on the original HU before you replaced it?

The AM stations on my car quit working a little while ago, but the FM stations still come in, although they don't seem to be as strong now.

Not sure where the antenna amplifier is on a vert but in the hardtops it is in the antenna base. Water gets into the base and the circuit boards in the base corode and short out.

If you still have the factory HU you can re-install it and run a diagnostic on the radio with VCDS (Vag-Com). You can elimitate any antenna wiring problems if there are no fault codes. The antenna may still need some sort of power supplied to funcion correctly, but if there are no fault codes with the original factory HU installed you will know all the antenna hardware in the car is functioning as designed.

I did this with my car and got a fault code about an open circuit in the antenna. I removed the antenna base and opened it up and the circuit boards inside were covered in corosion. I tried cleaning the boards off with contact cleaner but it was too late, they are permantantley damaged.

EDIT: ADDED 3-15-2011

Comments below are purly how I "assume" the antenna system works in these cars - I am not an expert....

You may very well need some type of antenna power adaptor / amplifier as Audiomechanic mentioned in post #4. Does your car have a Monsoon audio system in it? If it does the wire you hooked up to could be the trigger/supply for the audio amplifier. On my car (2005 GLS with a Monsoon system) it appears all the antenna amplifier circuitry is located in the antenna mounting base, and the radio has the function of supplying the base with whatever power the circuits need through the antenna coaxial cable. When I had my base appart the coaxial cable is sodered to one of the circuit boards, and the antenna (mast) contact is located on the circuit board. There is no direct hookup between the coaxial cable and the antenna mast. My Bug is also equipped with XM radio, but the only cales that go into the antenna base are the coax for the AM/FM and two smaller coax cables for the satelite radio.

[azztin]

be sure that the power antenna wire did get hooked up, you can get reception but also lose a lot of reception without that being hooked up if these have power antennas.

[Droid]

[QUOTE=Audiomechanic;706161]I've never seen a Beetle without the little nub antenna on the back of the roof. Never seen one with the antenna running around the windshield.
QUOTE]


thats what you get when you get a convertible......you cant have the rubber duck on the back of the roof...as there really is no "roof" to speak of!