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post #1 of 13 Old 04-28-2020, 07:57 PM - Thread Starter
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Need help identifying what this is

Hi all,

Please bear with me. I can conceptualize what I'm after in my head, I just don't know how to articulate it using terms that yield results in Google and on this forum.

The gist: I need help identifying this connector (photos attached) so that i can replace it.

The background: I just bought a condo that was built in the early 80s. It has a centralized antenna system of some kind. What I can gather from research and talking to people is that the apartments are daisy chained together. Each apartment has three rooms with these jacks. Two of the three rooms have had the cables cut from the wall plate and joined together, essentially bypassing my unit. The third wall plate was painted over long ago and still had the wires connected.

What I'm trying to do is to replace all three plates with a modern equivalent so that I can restore service to all three rooms. Here's where my lack of nomenclature comes into play. In my gut of guts I know that the part I seek looks like a splitter, but is not a splitter. Adapter? Coupler? I know I need to allow the signal to pass through with minimal loss, but also spit it out to me. I'm not sure what ratings (ohm or otherwise) I need to be mindful of. The only thing I have is this painted over plate and an unhelpful building manager.

So, any ideas?
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post #2 of 13 Old 04-29-2020, 06:55 AM
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The "modern" equivealant would be an RG-59 (or RG-6) Keystone Coax connector plate.
But, they require "F" connectors (screw on ends) to be crimped onto the ends of the cable and then screwed into the double ended connector.
The problem with that is you have two wires that are also junctioned together at the plate (weird). That would normally be a RF splitter that is used for that.

I would clean up the plate, give the plastic a nice spraypaint of wall matching color, wire wheel the paint off the connector and put it back together.
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post #3 of 13 Old 04-29-2020, 08:18 AM - Thread Starter
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So, I'm with you on what to do on the plate side. There are a lot of options, I think, to ultimately get the feed into my apartment. The problem I can't work out is the what you called weird. And it is weird. I think this is the key to the whole operation.

After more digging, I think that this is a tap. Presumably the signal is coming from upstairs and needs to be passed downstairs with minimal signal loss. I don't think it's a splitter because, from what I'm reading, a splitter reduces the signal by half. Which would suck if you were on the ground floor of an 18 floor building. Conceptually, this makes sense to me. However, that's all that makes sense to me.

Anyone have an idea of what I may be able to replace it with? I'll look again for markings on the plate, but I don't think there are any.
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post #4 of 13 Old 04-29-2020, 10:44 AM
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I am wondering if they wired your house with the RG6 and linked them from room to room. Daisy chained.

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post #5 of 13 Old 04-29-2020, 11:57 AM
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It's a 'tap'. You need one of these for each room: https://www.ebay.com/p/1400248800?iid=253395905409
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post #6 of 13 Old 04-29-2020, 06:30 PM - Thread Starter
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Quote:
Originally Posted by FlyingDiver View Post
It's a 'tap'. You need one of these for each room: [link snipped]
Awesome. So we know what it is now. The next question is what rating tap I'd need. Now, I'm going to assume this is one of those things you can't know for sure unless you're in the room with the right equipment. The one you linked appears to passing through 2.8dB. That seems low. Am I reading the sticker correctly? Any advice on that?
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post #7 of 13 Old 04-29-2020, 06:42 PM
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I think what that's actually saying is that the OUT side is 2.8Db less than the input, and the unlabeled side is 6dB less. This is meant to "tap" and passthrough cable, so the IN side is upstream (towards the antenna), OUT is downstream (towards more taps), and unlabeled is the local device feed.

But it's been forever since I actually did any RF work and cared anything about dB losses.

Here's a better source: https://www.solidsignal.com/pview.asp?p=srt

As I recall, the trick here is to know what the signal strength is on the input line, then you use the appropriate tap value to give you sufficient signal for that outlet without reducing the downstream signal any more than necessary. Usually this is carefully calculated for the initial install, based on the source signal strength and the number of taps on the line.

Who's maintaining this system for the condo association? There should be someone. You need to figure out the topology of all the components before you have a chance of doing this right. And if there are other condo units downstream from you, you could mess them up seriously.
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post #8 of 13 Old 04-30-2020, 10:52 AM - Thread Starter
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Drats. We apparently don't have a guy and the condo association people don't really care much about it. There's a sort of "on your own" attitude. If I didn't care, I'd interpret that to mean "do what you want." But I'm not that sort of person. I don't want to impact the neighbors downstream. Just like I wouldn't want to be impacted by the people upstairs.

And then I go to bed thinking about the existing consequences of prior actions. In two of my three rooms, the tap has already been bypassed. Which conceivably means that everything downstream has been getting higher "In" dBs than was planned when the building was built. Don't know if that hurts. And of course, as you can see in the pictures, in the original install, there seems to be little to prevent the environmental impacts that surely bleed off downstream dBs. Exposed copper, no shielding, etc.

And then realizing that the association doesn't care because most people in the building have cable and don't use the building's antenna.

So, Hail Mary pass here: What happens if I oversize the tap? Completely making up numbers here. Let's say the real in is at 10dB. But the in on the tap is rated for 30dB with a 1db loss. Does the math still work out where downstream would get 9dB? And the tap gets whatever it's supposed to get? Wishful thinking? Feels like wishful thinking.
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post #9 of 13 Old 04-30-2020, 12:27 PM
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dB is a loss measure, not a signal strength. It's a percentage, sort of. But not a linear scale. So if you look at the specs linked from my link above, you'll see that as the larger the tap value (which means it's getting a smaller amount of the incoming signal), the smaller the loss is on the output size.

What you really need to do is use the largest tap value (most loss, least signal "stolen") that gives you an acceptable signal at the TV (for that tap). You might need to buy several and then return the ones you don't use. You might need a slightly smaller tap for each device going downstream from there.
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post #10 of 13 Old 04-30-2020, 09:36 PM
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I think the point about figuring out the topology of the system is the most important one in this discussion. If the wires go from unit to unit, the cut wires could be interrupting the signal going to units downstream from yours. And upstream damage could be preventing the signal from getting to you.

And more importantly in your discussions with other residents, have you determined if any of this even works at all? Is the antenna still standing? Its the wire running up the mast still in serviceable condition? Is there a distribution amp somewhere at the head end that still works? Or maybe it is unplugged? There are a lot of variables that could cause an arrangement like this not to work. And if everyone is using cable, maybe no one noticed when it stopped working? These things would be good to know before you spend a lot of time trying to patch up the wires in your unit.

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post #11 of 13 Old 05-01-2020, 08:22 AM - Thread Starter
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Quote:
Originally Posted by AlienWarlock View Post
I think the point about figuring out the topology of the system is the most important one in this discussion.
I know you're right. I wish it wasn't so. But doing this right is the only rational answer.


Quote:
Originally Posted by AlienWarlock View Post
And if everyone is using cable, maybe no one noticed when it stopped working? These things would be good to know before you spend a lot of time trying to patch up the wires in your unit.
I guess the quickest way to find out is to try it. Do I risk damage to the TV by plugging directly into feed without an intervening tap? I guess asking that question means that I should call in a professional to sort this out.

So, my next question is this: Who should I call? In a former life working the support desk at a telephone company, I used to tell people with inside wiring problems to call an electrician. That was the party line. However, an electrician always seemed like a skill mismatch to me. That said, other than the cable company, whose service I don't have, and who could care less about anything but getting a signal to their own box, I haven't found a service that talks about working on RF/coaxial related things. Even electricians. So, advice here?

Finally, thank you everyone for walking me through this. Especially FlyingDiver and AlienWarlock. You have been an immense help.
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post #12 of 13 Old 05-01-2020, 08:52 AM
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Look for a low-voltage specialist company. They usually do alarm and surveillance systems, audio/video distribution, and home automation. That's the most likely source. But these kind of antenna based distribution systems are really old school and there's not much expertise out there.

It's really unlikely that you would damage your TV by just hooking up to the cable. You might over-drive the tuner, in which case you'll get a crap signal. Or there might not be any signal at all.
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post #13 of 13 Old 05-01-2020, 01:49 PM
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Was probably working fine before.
Let's not overthink this one.
Clean er up and slide er back on the wall.

Starting to remind me of speaker wire towers...

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