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JohnRicketts
Occasional Visitor
Joined: Nov 12, 2006
Posts: 26
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 Posted: Sun Dec 10, 2006 2:33 pm Post subject: |
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| Sallyann wrote: | | JohnRicketts wrote: |
Having just hooked up to my fm car arial via a splitter, I'm not sure I understand this comment. If I'm right, the TMC plug is a combination TMC/headphone socket. The pin-out is (from the tip)
1 - left ear
2 - right ear
3 - TMC arial
4 - screen/0 volts
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John,
I'm afraid you have got the connections wrong. Using your numbering, 3 is the common return to the earpieces and 4 is the aerial. That makes it easier to solder because you are soldering to a large tag instead of a tiny pin. Also there is room to hold the tag with pliers to act as a heat shunt.
Have you included an isolating capacitor in the lead to the car aerial?
Sal |
Is there a qualified source for this pin-out, because connecting the FM arial to pin 3 (my terminology) and the coax screen to 4 gives me bucket-loads of TMC messages. I did not de-couple mine as the rear-quarterlight arial on my Galaxy is passive. If it wasn't such a pig to solder to pin 3, I'd swap it around and see if it made any difference. |
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Sallyann
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Joined: Jun 23, 2006
Posts: 768
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| Posted: Sun Dec 10, 2006 3:51 pm Post subject: |
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| JohnRicketts wrote: |
Is there a qualified source for this pin-out, because connecting the FM arial to pin 3 (my terminology) and the coax screen to 4 gives me bucket-loads of TMC messages. I did not de-couple mine as the rear-quarterlight arial on my Galaxy is passive. If it wasn't such a pig to solder to pin 3, I'd swap it around and see if it made any difference. |
John, all you have to go is pull the end tag off the Mio supplied aerial, and meter it back to the plug contacts.
I'm not surprised that you get some signal because the plug wasn't designed for RF and there will be enough coupling between the concentric conductors to let the 100MHz signal leak across. But it will work better with a direct connection.
Sal |
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JohnRicketts
Occasional Visitor
Joined: Nov 12, 2006
Posts: 26
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| Posted: Sun Dec 10, 2006 4:09 pm Post subject: |
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| Sallyann wrote: | | JohnRicketts wrote: |
Is there a qualified source for this pin-out, because connecting the FM arial to pin 3 (my terminology) and the coax screen to 4 gives me bucket-loads of TMC messages. I did not de-couple mine as the rear-quarterlight arial on my Galaxy is passive. If it wasn't such a pig to solder to pin 3, I'd swap it around and see if it made any difference. |
John, all you have to go is pull the end tag off the Mio supplied aerial, and meter it back to the plug contacts.
I'm not surprised that you get some signal because the plug wasn't designed for RF and there will be enough coupling between the concentric conductors to let the 100MHz signal leak across. But it will work better with a direct connection.
Sal |
Thanks. Did think about doing that, but did not want to mutilate my 1 day old TMC arial as I will be keeping it for fly-drive trips. Just digging out soldering iron...will swap connections and report back shortly......... |
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JohnRicketts
Occasional Visitor
Joined: Nov 12, 2006
Posts: 26
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| Posted: Sun Dec 10, 2006 4:29 pm Post subject: |
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| JohnRicketts wrote: | | Sallyann wrote: | | JohnRicketts wrote: |
Is there a qualified source for this pin-out, because connecting the FM arial to pin 3 (my terminology) and the coax screen to 4 gives me bucket-loads of TMC messages. I did not de-couple mine as the rear-quarterlight arial on my Galaxy is passive. If it wasn't such a pig to solder to pin 3, I'd swap it around and see if it made any difference. |
John, all you have to go is pull the end tag off the Mio supplied aerial, and meter it back to the plug contacts.
I'm not surprised that you get some signal because the plug wasn't designed for RF and there will be enough coupling between the concentric conductors to let the 100MHz signal leak across. But it will work better with a direct connection.
Sal |
Thanks. Did think about doing that, but did not want to mutilate my 1 day old TMC arial as I will be keeping it for fly-drive trips. Just digging out soldering iron...will swap connections and report back shortly......... |
OK. I just swapped the connection. It still found 10 pages of traffic messages so I guess you are right. (why would I need to know about standing traffic on the A92 which is 393 miles away??) So I wasted 3 plugs and 2 hours yesterday trying to solder onto the rings when the tab was staring me in the face!!! Doh! |
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Sallyann
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Joined: Jun 23, 2006
Posts: 768
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| Posted: Sun Dec 10, 2006 4:57 pm Post subject: |
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| JohnRicketts wrote: |
(why would I need to know about standing traffic on the A92 which is 393 miles away??) |
I suppose the reason is that if you are planning a long journey, the unit will want to know if there are roadworks that might affect the route.
Sal |
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DeeJay01
Regular Visitor
Joined: Mar 25, 2006
Posts: 139
Location: London
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| Posted: Mon Jun 04, 2007 2:19 pm Post subject: |
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| Sallyann wrote: | | JohnRicketts wrote: |
Having just hooked up to my fm car arial via a splitter, I'm not sure I understand this comment. If I'm right, the TMC plug is a combination TMC/headphone socket. The pin-out is (from the tip)
1 - left ear
2 - right ear
3 - TMC arial
4 - screen/0 volts
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John,
I'm afraid you have got the connections wrong. Using your numbering, 3 is the common return to the earpieces and 4 is the aerial. That makes it easier to solder because you are soldering to a large tag instead of a tiny pin. Also there is room to hold the tag with pliers to act as a heat shunt.
Have you included an isolating capacitor in the lead to the car aerial?
Sal |
Hi Sal,
I'm just about to buy the splitter to enhance the TMC signals to my Mio. Can I confirm that Pin 4 is the TMC arial and Pin 3 is the ground.
I hope to get to Mapplins/RS today
_________________
Regards
Dave J |
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Sallyann
Lifetime Member
Joined: Jun 23, 2006
Posts: 768
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| Posted: Mon Jun 04, 2007 4:48 pm Post subject: |
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The 'screen' tag on the plug is the aerial connection, yes.
There is no connection provided for an earth return as such, since the unit was designed for a single monopole quarter-wave as provided.
Pin 3 is the common return for the left and right audio channels.
I would personally never connect a coax screen to any point on the GPS unit that wasn't designed for it. It might very well work, but it will create an earth loop that (a) could induce ignition noise into the TMC receiver thus reducing signal quality and (b) it's possible under certain fault conditions on the car radio for a potentially damaging or dangerous current to flow through the GPS unit.
If I was using a coax splitter off the car aerial I would connect only to the centre of the coax using as short a length of single insulated wire as possible, and fit in series a blocking capacitor of about 100pF in case the car radio has DC on its aerial connector to drive an active aerial - many do these days.
Let us know how you get on.
Sal |
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DeeJay01
Regular Visitor
Joined: Mar 25, 2006
Posts: 139
Location: London
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| Posted: Mon Jun 25, 2007 5:41 am Post subject: |
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| Sallyann wrote: | The 'screen' tag on the plug is the aerial connection, yes.
There is no connection provided for an earth return as such, since the unit was designed for a single monopole quarter-wave as provided.
Pin 3 is the common return for the left and right audio channels.
I would personally never connect a coax screen to any point on the GPS unit that wasn't designed for it. It might very well work, but it will create an earth loop that (a) could induce ignition noise into the TMC receiver thus reducing signal quality and (b) it's possible under certain fault conditions on the car radio for a potentially damaging or dangerous current to flow through the GPS unit.
If I was using a coax splitter off the car aerial I would connect only to the centre of the coax using as short a length of single insulated wire as possible, and fit in series a blocking capacitor of about 100pF in case the car radio has DC on its aerial connector to drive an active aerial - many do these days.
Let us know how you get on.
Sal |
Sally,
I remember you helping me with this request before but I never did get around to actually doing it. I have another question.
Where can I find the car aerial splliter. When I asked the guy in Maplin he looked at me as if I was crazy or as if I asked him for a Burger from McDonalds.
_________________
Regards
Dave J |
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Sallyann
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Joined: Jun 23, 2006
Posts: 768
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| Posted: Mon Jun 25, 2007 9:55 am Post subject: |
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Sorry, I can't help you there. As discussed previously I use a separate wire. Hopefully someone who has one will pop up and tell you.
Sal |
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DeeJay01
Regular Visitor
Joined: Mar 25, 2006
Posts: 139
Location: London
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| Posted: Wed Jun 27, 2007 3:40 pm Post subject: |
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| Sallyann wrote: | Sorry, I can't help you there. As discussed previously I use a separate wire. Hopefully someone who has one will pop up and tell you.
Sal |
Sally,
If you use a seperate wire, how does it connect back into the radio antenna. I'm really confused now.
_________________
Regards
Dave J |
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mikealder
Pocket GPS Moderator
Joined: Jan 14, 2005
Posts: 19638
Location: Blackpool , Lancs
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| Posted: Wed Jun 27, 2007 3:53 pm Post subject: |
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| Aerial Socket and an Aerial Plug (assuming your car uses "normal" connectors) then simply solder a short length of coax between the plug/ socket and bring a single core wire from the centre contact to feed the RDS-TMC input - Mike |
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Sallyann
Lifetime Member
Joined: Jun 23, 2006
Posts: 768
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| Posted: Wed Jun 27, 2007 7:51 pm Post subject: |
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| DeeJay01 wrote: | Sally,
If you use a seperate wire, how does it connect back into the radio antenna. I'm really confused now. |
I found that the supplied aerial wire was quite efficient when suspended from the rear view mirror, but being thick and light coloured was annoying in the field of view and also an advertisement when the car was parked. I replaced it with a similar length of very thin enamelled copper wire hung from the mirror, that is practicaly invisible both inside and outside the car.
Sal |
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DeeJay01
Regular Visitor
Joined: Mar 25, 2006
Posts: 139
Location: London
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| Posted: Thu Jun 28, 2007 9:40 am Post subject: |
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| mikealder wrote: | | Aerial Socket and an Aerial Plug (assuming your car uses "normal" connectors) then simply solder a short length of coax between the plug/ socket and bring a single core wire from the centre contact to feed the RDS-TMC input - Mike |
I'm a bit confused Mike
If I only have 1 areial in my car which is plugged into my CD/Radio what will I plug the aerial plug into
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Dave J |
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GPSBear
Regular Visitor
Joined: Jul 15, 2006
Posts: 137
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| Posted: Fri Jun 29, 2007 8:46 am Post subject: |
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Unplug the cable from the radio, plug it into the new socket, plug the new plug into the radio.
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Mio C710 on MioMap 3.3 |
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DeeJay01
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Joined: Mar 25, 2006
Posts: 139
Location: London
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| Posted: Fri Jun 29, 2007 2:55 pm Post subject: |
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| GPSBear wrote: | | Unplug the cable from the radio, plug it into the new socket, plug the new plug into the radio. |
From what I can understand, all that does is gives me an extension to what exists already.
I think I need 1 socket to go into outputs (1 being a plug and the other for the areial wire for the TMC) that way I can plug it into the radio and the MIO at the same time.
Can I confirm that this is correct.
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Dave J |
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