300 ohm twin lead wire cut, how to rejoin - AVS Forum
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post #1 of 11 Old 07-08-2008, 05:01 PM - Thread Starter
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I'm trying to get Mom's TV, (she's 85), to get OTA DTV channels and I'm not doing too bad. I got her a Zenith DTT900, (dated April 2008) and hooked it up to her existing rooftop VHF/UHF antenna. At first, I got all Philadelphia locals with the exception of WHYY ch12, which is broadcasting at half power on digital. Then ch6 ABC and ch10 NBC started breaking up. All others have good signal. I traced wires from antenna down two stories, through the wall, with heavy rubber black twin lead. Just inside the house, only about 15 inches in, the black rubber twin lead was cut (many years ago, who knows why), and there was the regular brown twin lead going up through the floor to the TV. Joining this mess was an old Archer splitter combiner (15-1136). This appeared to be hooked up properly, but as a test I removed it from the circuit and twisted the two 300 ohm lines together. Much to my surprise, all channels came in with about 90% good signal, (we're 10 miles from the towers). Every station (29 of them) came in terrific, including WHYY 12. The bad news, now ch6 (RF64) ABC now has poor signal quality. Is there a modern version of the splitter, or do I need an amplifier? I'm trying to do this on a budget, so replacing the twin lead with coax is out right now. Is there a better way to join two twin leads?

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post #2 of 11 Old 07-08-2008, 07:24 PM
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Quote:
Originally Posted by lionelbob View Post

I'm trying to get Mom's TV, (she's 85), to get OTA DTV channels and I'm not doing too bad. I got her a Zenith DTT900, (dated April 2008) and hooked it up to her existing rooftop VHF/UHF antenna. At first, I got all Philadelphia locals with the exception of WHYY ch12, which is broadcasting at half power on digital. Then ch6 ABC and ch10 NBC started breaking up. All others have good signal. I traced wires from antenna down two stories, through the wall, with heavy rubber black twin lead. Just inside the house, only about 15 inches in, the black rubber twin lead was cut (many years ago, who knows why), and there was the regular brown twin lead going up through the floor to the TV. Joining this mess was an old Archer splitter combiner (15-1136). This appeared to be hooked up properly, but as a test I removed it from the circuit and twisted the two 300 ohm lines together. Much to my surprise, all channels came in with about 90% good signal, (we're 10 miles from the towers). Every station (29 of them) came in terrific, including WHYY 12. The bad news, now ch6 (RF64) ABC now has poor signal quality. Is there a modern version of the splitter, or do I need an amplifier? I'm trying to do this on a budget, so replacing the twin lead with coax is out right now. Is there a better way to join two twin leads?

At 10 miles from the tower an amplifier is unneeded.

If you want a 'make do' splice better make a splint. Take a popsicle stick
(or anything similar) and tape each cable to it so they can't move. Twist each wire splice tight, put tape around each bare copper wire, then over wrap these keeping spaced apart the same as in the cable.

You could replace the twin lead with coax just from the splice. You would use a length of coax and a 300/75 ohm transformer (one for attaching to the cable, one for the tv set antenna terminals).
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post #3 of 11 Old 07-09-2008, 05:49 AM
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Make the splint, then just use a set of wire nuts to connect the two sections of twin lead, and then tape with electrical tape.
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post #4 of 11 Old 07-11-2008, 09:45 AM
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Quote:
Originally Posted by lionelbob View Post

I'm trying to get Mom's TV, (she's 85), to get OTA DTV channels and I'm not doing too bad. I got her a Zenith DTT900, (dated April 2008) and hooked it up to her existing rooftop VHF/UHF antenna. At first, I got all Philadelphia locals with the exception of WHYY ch12, which is broadcasting at half power on digital. Then ch6 ABC and ch10 NBC started breaking up. All others have good signal. I traced wires from antenna down two stories, through the wall, with heavy rubber black twin lead. Just inside the house, only about 15 inches in, the black rubber twin lead was cut (many years ago, who knows why), and there was the regular brown twin lead going up through the floor to the TV. Joining this mess was an old Archer splitter combiner (15-1136). This appeared to be hooked up properly, but as a test I removed it from the circuit and twisted the two 300 ohm lines together. Much to my surprise, all channels came in with about 90% good signal, (we're 10 miles from the towers). Every station (29 of them) came in terrific, including WHYY 12. The bad news, now ch6 (RF64) ABC now has poor signal quality. Is there a modern version of the splitter, or do I need an amplifier? I'm trying to do this on a budget, so replacing the twin lead with coax is out right now. Is there a better way to join two twin leads?

LB
Nice job try visiting tvfool.com to make sure antenna is pointed correctly.
i know its tough when on a budget. Scrap Coax can be found free at the little dish installers places. Sounds as if you only need about 50 feet.
Also was there any corrosion at the antenna connection point ?
I will be doing the same project for my mother in philly burbs. She's had cable
(expanded basic @ $55.00month) the last couple of years but really only watches network tv.
regards
Owenf
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post #5 of 11 Old 07-11-2008, 09:45 AM
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300 ohm twin lead is lower loss than RG6. Switching to RG6 will decrease your signal. Make a good splice and that will get you the best signal.

Years ago I installed twin lead in my house that had a 125' run from my antenna to the TV. I had one channel that was so so. Some $*@% guy at an electronics store told me I would get a better picture with coax. I spent all day removing the twin lead and replacing it with coax pulling it through the walls. I lost over half of my stations. I then had to spend a second day pulling out the coax and replacing it with the twin lead again.

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post #6 of 11 Old 07-12-2008, 03:18 AM - Thread Starter
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OWENF:

When I get off my 4-day-in-row-12-hour night shift stint, I'm going back to Mom's and clean cut, re-strip and solder the twin lead. I'll try the popsicle stick idea.

Failing that, I'm going to try attaching a transformer balun and run a temporary coax up the steps, just to see the results before I go tearing her carpets apart to re-drill.

Antennaweb says that 19124 is sorta borderline yellow - green, for 6ABC post transition, must be some hill or buildings in the way. I may have to go with active splitter to boost signal.

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post #7 of 11 Old 07-12-2008, 07:41 AM
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While twin-lead does have lower loss than co-ax, twin-lead requires very careful installation. The stand-offs must be correctly placed and the the twin-lead must not be near any objects or walls. Sunlight and weather also cause twin-lead to deteriorate rapidly.

Kevin
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post #8 of 11 Old 07-14-2008, 09:08 PM - Thread Starter
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Current status:

I tried the 300 ohm splint repair, after stripping wires, keeping proper distance distance between wires. Still, Mom gets 27 local channels at 90 % signal, but WPVI 6 says no signal. 300 ohm brown wire was probably original inside 55 year old house. Wire downlead is about 15 years old, and is black and foam core.

I installed balun transformer at down lead, and I ran a 25ft RG6 from house entry point to dtt900, same results,

I tried swapping out the DTT900 for another that I have at my house (WPVI works at my house), just to eliminate a box failure, same results.

I recall, that i did actually get 6WPVI before removing the old splitter.
Is it possible that WPVI6 is TOO strong?

The most annoying thing is considering 9.2 miles from antenna farm in manayunk, all channels 3, 10.1, 10.2, 12.1,2,3 17.1,2 (23.1 (!New Jersey!) 29, 44 (don't know) 48,1,2,3,4,5, 57, 61,1 ION, abunch of 62,s 65,s, all come in at 90% signal.

What could be different about WPVI6/ (UHF RF64). Watching the DTT900 try to tune in WPVI6, I see a jump to about 90 percent, then it drops to 30 % bad.

Where do I go from here, active splitter, inline amplifier, passive splitter.

Would an FM demodulator help?

Toy trains are like women's breasts, designed for children, but older men end up playing with them.
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post #9 of 11 Old 07-17-2008, 07:34 AM
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Check out what the analog stations look like, especially in the upper UHF region. Do you have multipath problems???

Also, is the antenna pointed correctly? And of course ....did you make sure the twinlead's contact with the antenna is good. It wouldn't hurt to lop off an inch and re-connect it.

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post #10 of 11 Old 07-17-2008, 08:46 AM
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Quote:
Originally Posted by lionelbob View Post

Watching the DTT900 try to tune in WPVI6, I see a jump to about 90 percent, then it drops to 30 % bad.

That is indicative of "multipath". You may want to try re-aiming the antenna (actually, "mis-aim" silghtly). A slight reduction of signal of the other channels may help resolve the possible multipath issue with WPVI.

Or... add a splitter back into the mix (to attenuate the signal) and see if it helps.
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post #11 of 11 Old 09-10-2008, 09:40 PM - Thread Starter
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I just felt it polite to post the "end game" of this thread. You guys were right. I had a contractor replace the mangled mess of wires and run a new RG6 from the 23 yr old antenna to the converter box. All digital channels have 90% now, mom gets 33 stations. Just in time for her "Dancing with the stars" fave.

Thanks a lot for help and directions.

Regards, Bob

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