Which is it, RG59 or RG6?
in [Repair]
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From: Robert Macy on 6 Dec 2009 13:52 On Dec 6, 9:30 am, Jeff Liebermann <je...(a)cruzio.com> wrote: > On Sat, 5 Dec 2009 20:30:48 -0800 (PST), Robert Macy > > <m...(a)california.com> wrote: > >Sorry, for jumping in here in the way of Jeff's capable hands, > > Grumble... > ....snip... > -- > Jeff Liebermann je...(a)cruzio.com > 150 Felker St #D http://www.LearnByDestroying.com > Santa Cruz CA 95060http://802.11junk.com > Skype: JeffLiebermann AE6KS 831-336-2558 LOL!
From: mm on 6 Dec 2009 15:04 On Sun, 06 Dec 2009 09:17:54 -0800, Jeff Liebermann <jeffl(a)cruzio.com> wrote: >On Sun, 06 Dec 2009 12:03:52 -0500, mm <NOPSAMmm2005(a)bigfoot.com> >wrote: > >>On Sun, 6 Dec 2009 00:24:47 -0800, "Joe Rooney" >><ikerooneyat(a)bigvalley.net> wrote: > >>>Keep in mind a 3 way splitter has two 3.5db and one 7 db out. > >Wrong. A splitter reduces the output by -3dB which is half the power. >The extra -0.5dB loss is from losses in the bifilar wound xformer. If >two of the ports each have half the input power, there's nothing in >the budget left for the 3rd port. > >Googling for a typical 3 way splitter: ><http://www.twacomm.com/catalog/model_CT413.htm?sid=1F79205DEA0D1B9FF1BF82ACDC4C33D2> It says "3 way-loss 2 at 6.5 DB, 1 at 3.5 DB, 20 DB isolation DC passive" What does DC passive mean? Will it transmit DC power to an amplified antenna, for example? >I find 2 ports with -6.5dB loss and one port with -3.5dB, which makes >more sense. (Actually, it should be -7.0dB loss). > >A 3 port looks like a tree. It starts with a two port splitter, where >one output is brought out for -3.5dB loss. The other port goes to yet >another splitter, with again divides the output in half, for -7dB from >each of the two ports. >>Aha. That would certainly account for a difference! I'll check >>later today. In fact, I'll take out the splitter and connect just >>the one giving me trouble. > >Except that you said you're using 2 and 4 way splitters, which are far >more common than a 3 way. I did have a 4-way in there, but later on the slim possibility something was wrong with the splitter, I switched and the next one I found in my drawer was 3-way. Of course the problem pre-dates the 3-way, but I jumped to the conclusion that the 4 way might have had something like this too. I realize now I shouldn't have used a 4=way since i never had plans to use more than 3 of them, but 25 years ago, I iddn't know they made 3-ways. Thanks.
From: mm on 6 Dec 2009 15:18 On Sat, 05 Dec 2009 14:59:33 -0800, Jeff Liebermann <jeffl(a)cruzio.com> wrote: >On Sat, 05 Dec 2009 16:44:42 -0500, mm <NOPSAMmm2005(a)bigfoot.com> >wrote: > >>I gather from posts here that RG6 is better than RG59, is that right? > >Yep. RG-6/u is generally better for most everything. > >>Could the use of of RG59, 33 feet, for at least one tv be responsible >>for my bad reception on that tv? > >If the coax cable is in good shape, hasn't been eaten by rats, mice, >squirrels, kids, vacuum cleaners, etc. and has properly attached >connectors, then there's almost no difference in performance between >RG-59 and RG-6/u. In my limited experience, lousy connector crimping >and mouse eaten cables are the usual culprits. Thanks. I will check both those things next time I"m in the attic, some time this week. No problems in the part that shows. > >>I'm using co-ax for distributing tv from my DVDR to TVs throughout the >>house. (The DVDR tunes in the over-the-air digital signal and I have >>an RF modulator to change the DVDR output to analog. > >You must enjoy low quality video. It appears that you're also using >that derrangement to move audio, so the analog video is really NTSC >encoded with an approximately 4MHz maximum bandwidth. If all you have >is an analog TV, that's fine and will work, but if you're watching >this on a digital capable TV, it's wasting the capabilities of the TV. No, I can't afford any digital stuff. I've only bought one TV in the last 37 years, but I get more than 50 of them at yard sales or out of the trash. Some work when I get them, some I can fix, some I can't. So I have to wait until I find some digital stuff cheap, and that's been slowed down because as of a month ago the county trash collection will no longer pick up tvs. People have to arrange to take them to 3 locations in the county. For many, the closest is 10 miles away. >Incidentally, thanks for leaving out all the make and model numbers, >as well as most of the numbers. That adds some credibility to my >guess work. If you want help with your SPECIFIC problem, it helps to >supply some specifics as to what manner or video problem you're seeing >and what manner of hardware you have to work with. I should have mentioned in the first post that today I tried another tv, and it had the same problem with the picture. OTOH, a second tv connected to the same splitter, and also using a different splitter, displays a perfect picture. The two tvs with bad pictures in this room were a 12" Zenith 5 or 10 or 20 years old and 12" Magnavox with a VCR in the same age range. I can give you model numbers if you want. But since they both give perfect pictures when the signal is from the set-top box on top of the tv, I didn't think the tv was the issue. > >>I did the wiring >>to the tvs 25 years ago, and I used left-over and scrap co-ax, so the >>co-ax is older than 25 years. > >Ok, the coax is suspect. This is easier to troubleshoot by >substitution. Find a 50ft piece of decent 75 ohm coax cable. Run it >in place of the suspected 33ft piece. If it magically fixes the >problem, your old coax is history. I should have thought of that. I can run it through the trap door to the attic. No need to remove the stuff that is there. My long pieces of coax are buried in the basement This will have to go back on the back burner until then. >Also, if you have a scope and are interested in building a TDR (time >domain reflectometer), you can test the cable. ><http://en.wikipedia.org/wiki/Time-domain_reflectometer> ><http://www.epanorama.net/circuits/tdr.html> I think you had the right idea the first time, substitution. >>Did they have RG-6 25 or 30 years ago? > >Oh yes. It was in the original military "radio guide" MIL-HDBK-216 >from WWII. The "6" means page 6 of the guide. Very interesting. >>I didn't pay attention then so I don't know what most of it is, but >>the 33 foot piece going to this one tv is RMS Electonics Inc. 59/U. >> >>Everything was fine until the digital conversion, and now this tv that >>I watch a lot shows a grainy picture. All the other tvs have great >>pictures, and even for this one, when I supply a signal directly from >>a set-top digital converter box, only 3 feet of cable, it shows a >>perfect picture**. > >I guess "grainy" means you're getting a weak signal. Well, drag one >of your other TV's over to this location and see if it's a consistent >problem. If the 2nd TV is also "grainy", then you probably have a low >signal level for some reason. Again, it can be the cable or the >connectors. A broken shield connection will still deliver a signal, >but at somewhat lower level. Also, substitute the coax with a known >good one as I previously suggested. Will do. >>Do you think replacing the RG59 with RG6 will get me the perfect >>picture other sets get? > >Dunno. I would find the cause of the problem before ripping out the >cable. However, if it's easy to get to and doesn't make too big a >mess, it's worth a try. Either RG-59 or RG-6/u will work as you're >only using it on Channel 2 or 3 with the RF modulator. The attic gets fuller and fuller, mostly empty boxes, and more insulation, and I'm 25 years older. It still woudln't be so hard to replace the cable, if the substitute works right. But it would be a lot easier, i realize now, to bypass the splitter and connect the problem tv directly. Or to bypass the cable and run another one temporarily outside the wall, not in it. >However, if you were going to shovel the entired TV spectrum, from VHF >to the top of UHF through the cable, as you will if replace your >analog TV with a DTV, then I would use RG-6/u. It'll probably be 10 more years before I have a digital tv in this room. >>I didn't use home-runs, just splitters and >>every two splitters a signal amp, a total of three signal amps, one >>with 2 or 4 outputs, and two with 2. > >Holdit. Any one of these can be the problem. That includes >amplifiers and splitters with unterminated outputs. I don't have any unterminated outputs. >First, you don't >really need all those amplifiers. I take it back. Now I think I only have two amplifiers. For years I was sure that I had 3, maybe I do but I can't figure out where the third one would be. Please forgive me. I put some of this stuff in 26 years ago and the rest 24 or 25 years ago. I plugged the amps in and haven't had to do a thing since. At least until this fall. 24 years with no maintenance needed is pretty good. Details about tv hookup below.** > Most TV's can easily handle one or >two 2 or 4 way splitters, without an amplifier. However, I have no >clue how much RF output your unspecified RF modulator belches or what >your amplfiers are doing. I certainly don't know, but it's conceivable that the RF modulator puts out much more than the various VCR's I used did, but all I did about 18 months ago was replace a mediocre VCR with a Philips DVDR3576H DVD recorder with 160 Gig hard drive, and add a RF modulator that cost about 18 dollars on Amazon, and everything worked and I didn't verify any of the outlying circuitry or tvs. I'm 99% sure even this tv gave no problems then , 18 months ago, and only gave problems last June when the analog stations went away. I had been watching analog for a whole year even after I had a digital tuner, because channel surfing is much quicker in analog. >I also can't guess your topology (wiring >layout). My guess(tm) is that you have too many amplifiers or one of >them is unplugged or dead. If one were unplugged, at least one other tv would have little or no picture. I think. Since every amp suplies signal to at least two tv's. But after I try substituting the cable, I will look again at the main amp. >Try replacing the amps with an ordinary 2 >way or 4 way splitter and see if it magically fixes the problem. Also, Not likely, because I didn't put the amp in until the signal was too weak and the picture was washed out. Only if the RF modulator puts out a substantially stronger signal than the first VCR did. But I appreciate the suggestion and will try it if all else fails. >if you don't have a CATV signal level meter, walk the TV around to the >various amps until the bad section or amplifier is found. If you have >any unterminated outputs, kindly terminate them with a 75 ohm >terminator. > >>Would an additional signal amp >>at the start of the RG-59 also give me perfect or at least improved >>reception? > >No. You already have too many amplifiers. You'll do better by >getting rid of amps or at least finding which one is the culprit. It >might still be the coax, but I'm more inclined to guess(tm) that one >of the amps if fried or sick. But every amp supplies signal to more than one tv, and only this one tv has a problem. >> **(But the set-top box isn't connected to the main antenna and >>doesn't get several stations I watch, nor will it play what is >>recorded on the DVDR.) > >You lost me. What does this have to do with anything? Draw you Sorry. Not important. Never mind. >topology (wiring) and post it somewhere. Don't forget to include some >numbers. I'm good at neither drawing nor posting. Last time I tried posting, it was a time-consuming failure. But I think I can describe it clearly. **I was running 8 tvs but now I'm running 7 off of the DVDR, formerly the VCR, and I never put in an amplifier until I put in another splitter, ran co-ax to another room and connected a tv and saw that the picture was washed out. The VCR, now DVDR, is in my bedroom. (I used to have Comcast cable that went to the VCR.) The output from the DVDR goes to the closet where there is a 4 way amplifier, with one output terminated, one to the tv right there in that bedrroom, one to the attic (A), and one to the first floor & basement (B). (A) goes into the attic and 20 feet away splits 3 ways, one terminated***, one to the tv in the bathrom which has a perfect picture, and one to the tv in the office/spare bedroom, with the problem picture. ***When I spent more time in the attic, I had a tv stored up there, that I watched, and it used the now-terminated output. (B) goes to the first floor and a two way splitter, one output to the living-room tv, and one output to the basement. In the basement family room is a another amplifier with two outputs, one output to the family room tv and one to the laundry room. In the laundry room is another splitter, one output to the laundry room tv (I needed a place to store an extra tv anyhow, so I might as well connect it) and one output upstairs to the kitchen. 7 tvs are connected, an eighth used to be.
From: mm on 6 Dec 2009 15:24 On Sat, 5 Dec 2009 20:12:17 -0800 (PST), "hr(bob) hofmann(a)att.net" <hrhofmann(a)att.net> wrote: > >Try connecting each set directly by replacing the splitters with thru >connectors and see if they all work ok. This will require that you >undo and redo a bunch of connections as you check out eachset and >associated cables,, but it is the only way to be sure that your basic >components are good. I agree with other posters that bad crimp >connectios are a frequent problem. A little corrosion aftrer 25 years >may make the contact between the outer shield/aluminum ground wire to >the connector outer housing intermittent and that can do wonderous >things. If the output of the dvr is of typical levels, it should >easily drive another set 30 feet away. I have a 3-way splitter on the >output of my cable box and it drives the nearby tv as well as two >other sets 30 feet away, using a 1-3 splitter, with perfect pictures. When I first got cable tv -- I don't have it anymore --, the guy ran the cable in through the floor of the close, which overhangs the first floor. The cable box connected to a channel control dial via a cable, no infra-red, and I told him I wanted to keep the box in the closet, out of my way. He said he wasnt' sure if the tv could that far from the box. The tv was about 6 feet away. Later when I connected the first remote tv and was running the co-ax through the basement ceiling, so for some reason it was 3 times as long as it would be when I was done, it was about 120 feet and it still worked fine, but he thought 6 might be too much. (I didnt' get the slightest impression he was looking for a tip for him to make a wire 7 feet long, but maybe I'm dense and that's what he wanted?? That didn't occur to me until just now.)
From: Jeff Liebermann on 6 Dec 2009 18:28
On Sun, 06 Dec 2009 15:04:23 -0500, mm <NOPSAMmm2005(a)bigfoot.com> wrote: >>Googling for a typical 3 way splitter: >><http://www.twacomm.com/catalog/model_CT413.htm?sid=1F79205DEA0D1B9FF1BF82ACDC4C33D2> > >It says "3 way-loss 2 at 6.5 DB, 1 at 3.5 DB, 20 DB isolation DC >passive" It should be 7dB, not 6.5dB but close enough. >What does DC passive mean? Will it transmit DC power to an amplified >antenna, for example? Yep. DC passive means that there is DC continuity between the ports. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |