Satnav Antenna splitter for TMC reception

[Willem]

I am using a seperate GPS/TMC receiver from GNS for a navigation system. As you all problably know the TMC part is in fact a FM/RDS tuner. I read some succes stories about getting a better TMC signal when connecting the TMC receiver to the car antenna by using an antenna splitter.
So I bought one from GNS (see http://www.gns-gmbh.com/catalog/prod...bc704b2918d6b1)
After quite some work (changes connectors, opening dashboard etc.) I could finally connect the splitter and test it. But then it appeared that I couldn't receive any radio station anymore and also did not get any TMC information via the GPS/TMC receiver. Checked the splitter, all connections and wires but found nothing wrong. The splitter simply seems to block or disturb the antenna signal coming from the antenna amplifier mounted in the rear window.
Is somebody out there who tried the same or can anybody help me in one way or another?
I tried to get the schematics of the radio and the antenna amplifier but my dealer could only get the wiring diagrams, not the internal schematics.

Thanks in advance.

[pcr]

Straight off the top of my head, I have no experience of this. Try to determine if you have a weak signal or no signal. Using an alternate radio may help here. If no signal, then consider how the aerial amplifier is powered, does the head unit sense it's presence and apply power accordingly ?. Is the aerial amplifier powered via the aerial lead ?. Isn't it frustrating to have to guess at these things.
Regards, pcr.

[Willem]

Originally Posted by pcr

Straight off the top of my head, I have no experience of this. Try to determine if you have a weak signal or no signal. Using an alternate radio may help here. If no signal, then consider how the aerial amplifier is powered, does the head unit sense it's presence are apply power accordingly ?. Is the aerial amplifier powered via the aerial lead ?. Isn't it frustrating to have to guess at these things.
Regards, pcr.

Thanks for you reaction. I have a very weak signal with the splitter connected. I did not try an alternate radio, to be done. The aerial amplifier is powered by a separate power lead (visible on the wiring diagrams that I got from my dealer), connection was ok. So the strange thing is that everything seems to be ok but it isn't.

The only thing that I could not do was a connection check from the inside of the radio to the outer connection of the splitter going to the aerial antenna. I used an "antenna adapter Honda USA" (see this link: http://www.tomacarparts.nl/Downloads/11a.pdf) to be able to insert the GNS splitter which looks not so robust (thin wires and so on), so maybe I have to look in that direction.

[pcr]

Willem,
The splitter you are using is said to be incompatible with a certain Medion GPS device, might this apply to yours ?.
If the splitter is passive there may be a 50% loss of signal strength. Bearing in mind there may be issues with the radio reception anyway (see forum) what you are trying to do may leave you with poor reception.
What happens when you use the splitter with just the radio or just the TMS receiver connected ?. Also, try a 1 metre piece of wire in place of the aerial.
Regards, pcr.

[Willem]

Originally Posted by pcr

Willem,
The splitter you are using is said to be incompatible with a certain Medion GPS device, might this apply to yours ?.
If the splitter is passive there may be a 50% loss of signal strength. Bearing in mind there may be issues with the radio reception anyway (see forum) what you are trying to do may leave you with poor reception.
What happens when you use the splitter with just the radio or just the TMS receiver connected ?. Also, try a 1 metre piece of wire in place of the aerial.
Regards, pcr.

Its a GNS GPS/TMC receiver, that's why I bought the GNS splitter. It is a passive splitter, so of course you lose signal strenght, but one should not expect to loose soo much signal that reception of a radio station is hardly possible anymore.