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mhamel 11-27-2009 06:58 PM

unknown wall jack / receptical (see pics)
4 Attachment(s)
I purchased a condo a couple of months ago and I since then I have been trying to figure out what the receptical on my wall is used for.

My first guess was that it was for a tv antenna. I've since tried connecting a tv and there is no signal whatsoever, this could mean that the antenna is no longer attached/functional, but I suspect this is not the case, as one of the leads is coming from above, the other below. If it were a tv antenna, I suspect that would both be coming from above.

Someone else suggested that this might be some type of ground, I suspect this is not the case either.

On the front this wallplate has two screw, presumably you would connect a wire to each, on the backside it appears that there are two coaxial cables attached. (please see the attached pictures)

Any help would be greatly appreciated.


voiles 11-27-2009 07:07 PM

wall plate
that plate is for a tv antena

Billy_Bob 11-27-2009 07:35 PM

TV antenna connection. The wire going down probably goes to another condo. These systems many times would have an amplifier and antenna on the roof. Both may have been disconnected when cable TV came along?

I have an antenna and amplifier. I turn the amplifier off when not in use and I don't receive a thing.

Your connection was for when TV antenna wire used to look like this...

hayewe farm 11-27-2009 11:02 PM

It looks like it has been painted several times so you may not be getting and contact.

mhamel 11-27-2009 11:10 PM

unknown wall jack
2 Attachment(s)
I'd like to update this, does it make sense to hook these leads to a 300ohm to 75ohm adapter, then just plug that adapter into a standard cable jack?

Just to follow-up, it looks like two RG59 lines coming into this jack, not the twin-lead that I've commonly seen in my research, is that normal? There are only two wires, one coming into the jack from above, one coming in from below. This may be a naive question, but wouldn't there be two leads from the antenna before it would go to the unit below me?

Thanks for your quick replies, you've both been very helpful!

mhamel 11-28-2009 08:58 AM

unknown wallplate

Originally Posted by hayewe farm (Post 358455)
It looks like it has been painted several times so you may not be getting and contact.

Yes, it has been painted several times and is in desperate need of replacement. I tried connecting a 75 to 300ohm adapter directly to the wires (not sure if these transformers are one way, or if they can be used in these circumstances, so that definitely could be the reason I received no reception. Basic rabbit ears pick up multiple channels here).

Billy_Bob 11-28-2009 09:48 AM

The coax does have two leads, the outer braided "shield" and the inner wire. Notice your wall plate on the back has a big metal clamp which seems to be connecting the two shields from both wires together.

I would not disconnect the coax from the wall plate. These antenna systems are designed for an entire building with many connections and are adjusted to be just right for all apartments. So as installed it should work correctly, modifying it might make it not work for someone else. (If the building gets the system repaired.)

Best to use the 75 to 300ohm adapter with the existing wall plate and ask your maintenance person if the system can be repaired.

Use sandpaper to remove the paint from the underside of the screws if needed.

joed 11-28-2009 10:32 AM

It certainly looks like an old antenna connection. But who know where the other ends goes. It may have been abandoned years ago.

J. V. 11-29-2009 10:38 AM

I am no expert, but it would seem that all is needed is a splitter behind a single coax plate as shown in post #5. The white plate shown in the post would hide the splitter in the wall. I am guessing. And would try it.

hayewe farm 11-29-2009 05:46 PM

The wall plate you have has a built in 75 to 300 ohm converter plus probably a splitter to feed the the cable going down. If you use the adapter you posted in #6 connected to the screws it will convert it back so you can use a coax to the TV or use a 2 conductor TV lead from the plate to the screw terminals on the TV. You will need to clean the screws and the contact plate on the wall plate.

mhamel 11-29-2009 09:14 PM

Thank you all for the help, it has been invaluable. The braided shield explaination really cleared things up for me, thanks Billy Bob. I also appreciate your caution on the possibility of causing problems for others. I went ahead and used a balun to switch the signal back to 75ohm-- I just put the current plate behind the wall and installed a new coaxial plate to clean-up the room.

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