Thread: What is this cable?

Looking for help with a mystery cable. Please see pics.

I have an old cable running from the roof into the apartment. On the roof was a 'VHF Matching Box (75 [Unknown symbol] > 300 [same symbol])' that used to connect to one end of the cable. The box has a coaxial connector on the other end of the it. The cable is flat with two wires in it.

Any idea what this was used for? If it was connected to an OTA antenna, could I hook it up for that purpose again?

Thank you.

It's called a balun or a 75-ohm to 300-ohm transformer. Usually they're attached with screws to the antenna's feed lines, so that you can use regular coax cable to carry the signal.

Looks like you need a new one, and to figure out where it used to attach to the antenna. You can get one at any hardware store, usually for less than $4.

that is a converter used to hook up a 300ohm line to a cable ready tv or a coax line to an older tv that only had the 300ohm connection. yes it will work on the antenna but probably won't get much unless you have a digital tuner at this point

Thanks for the comments. I connected the box to my tv and the mystery cable, the result was 15 very good quality OTA channels on my tv, including some HD. Very pleased, especially as the other end isn't connected to an antenna, just lying on the roof.

Originally Posted by rcc147

Thanks for the comments. I connected the box to my tv and the mystery cable, the result was 15 very good quality OTA channels on my tv, including some HD. Very pleased, especially as the other end isn't connected to an antenna, just lying on the roof.

That's...impressive. If you can do that with no antenna at all, put a $10 set of rabbit ears with a 7.5" hoop up on the roof, and see what happens next...

That's amazing that you get all of those channels with something that small. I get 7 channels and require a big attena to get them.

rcc,

15 channels is pretty good, but, given your location, you probably have a LOT more available to you.

If you'll post your ZipCode, we can look up your Chart, and see if you can improve on that number.

Or, if you'd rather do it yourself, you can follow these...

LookUp & Posting Instructions for finding your Free Local TV Channels

Have a good Day !
S.W.

Tha little wierd looking thing was correctly identified as a matching balun, or matching transformer, it "transforms", the 300ohm feed from the two(2) connectors on your antenna to 75 ohm feed, that way you can use 75 ohm coax(standard tv/cable coax), instead of having to use 300 ohm 2 wire feed line all the way from the antenna, using "standoffs", as there was no sheilding really with the 300 ohm 2 wire feed line and you used to have to use standoffs with it all the way down the tower continuing into the house and connected to the older 2 wire feeds on the back of the older style tv's, if you did not use stand-offs you would lose alot of signal coming from the antenna.

If you were to get a new matching tranformer, an outdoor one, which comes with a weather boot, to aid keeping the water out of your 75 ohm coax, once 75 ohm tv/cable coax gets water in it, it degrades and will turn the sheilding and center conductor green, and you loose alot of signal.

Once you install an antenna, you will have much better picture quality and many more channels, the higher you get an antenna, and the least amount of obstructions the better they perform, presently with mine, and mine has a signal amplifier I can receive approx. 35+ channels perfectly, some from as far as 100 miles away (antenna sits on a fifty(50) foot tower) from Buffalo(US), Erie Pennsylvania(US), Ohio(US), Toronto(ONT.), Hamilton(Ont.), Kitchener(Ont.), Paris(Ont.), London(ont.) etc, I am located on the north shore of Lake Erie, near what is refered to as Long Point, Ont.

So as you can see, a properly set-up outdoor antenna blows an indoor,(rabbit ears, or an attic antenna), out of the water so to speak, simply because there is much less obstructions, be it house wiring, heating/cooling duct work or anything else that can interfere with signal reception.

So yeah, an outdoor antenna will help you out greatly.

Those services, in my opinion, that list what channels you can get from whatever zip or postal code can be rather decieving, and do not take into account the use of an amplifier, which can aid greatly in the reception of either non existant channels or weak ones to the point that they are recieved perfectly. With tv amplifiers it is a matter of db gain that can make the difference, the more gain the better.

Originally Posted by Bouncy64

2 wire feed line

The term you were looking for is "twin-lead".


Twin-lead - Wikipedia, the free encyclopedia