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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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Hi All,
I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. |
#2
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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In message , amdx
writes Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. Despite your long 170ft drop cable, were you getting good analogue signals before the change to digital? If so, it could be that something is not right. Normally, even if you have had only fairly mediocre analogues, the digitals are good. Otherwise.... It sounds like your signals are just too weak. As things are, and if you can, the obvious fix would be to overcome the substantial loss of the 170ft drop cable by fitting an amplifier at or near the utility post (not at your end), and power it with low voltage via the coax from your end (ie similar to a line-powered masthead antenna amplifier). However, you would need to consult with the cable company to see if they were OK with letting you do this. It could be that they might be able advise you on the most suitable amplifier to use. It's not rocket science, but you have to be a little careful not to break any of their rules and generally do anything they don't approve of. -- Ian |
#3
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On Feb 8, 2:00*pm, amdx wrote:
Hi All, I'm on a boat, about 170ft from the utility post. That's about 10dB loss at midband for RG6. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap.. That was just a 3dB boost. * That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. * *I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? Really? There are such things a power inserters and compatible drop amps that allow you to power the amplifier over the cable from the user end. For RG6 18ga stranded that is about 0.6V loss at 250mA and therefore doable, I would run two cables if there was a way to make it increase signal strength. Forget it. * Getting anymore from the cable company is not an option. * *Any ideas to get a better signal? * * * * * * * * Mikek Use a 15dB gain drop amp with power inserter, but that's just a guess. Would help if you actually knew signal levels like what the receiver requires for optimum reception and what the cable co sources. Putting the amplifier at source gives you a typical system noise figure of 3dB, but putting it at your end limits your NF to 10dB minimum from the start. |
#4
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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In article ,
amdx wrote: I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Adding an amp at the cable box isn't all that likely to work... you can try it, but don't get your hopes up. Unless the amp has a significantly lower "noise figure" than the RF front end in the cable box, all you'll be doing is adding noise... the desired signal will be stronger, but the noise will be stronger yet. Something you could do, is add a single-port RF amplifier right at the utility post splitter, where your tap comes off of the feed. You can buy amplifiers of this sort which are designed to receive "phantom power" through the coax cable... you'd install a "power injector" at your boat, which feeds a DC voltage up the coax to the amplifier. This is probably your best bet: - It would amplify the signal before it's attenuated by the 170-foot cable run. - It won't require a power supply at the post... just at your boat, where you already have power. - It shouldn't interfere with the other taps on the splitter, even when the amplifier is not receiving power from your boat. You'd be looking for an "antenna mast" type of preamplifier. The Channel Master 0068DSB or 7777, Winegard AP-8700 or AP-8275 or HDP-269, AntennaCraft 10G212, or one of the Blonder Tongue Galaxy III models might do the job for you. You'll probably want a "75 ohm in, 75 ohm out" model, which would connect directly to the 75-ohm coax. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#5
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On Feb 8, 12:00*pm, amdx wrote:
Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap.. * That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. * *I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. * Getting anymore from the cable company is not an option. * *Any ideas to get a better signal? * * * * * * * * Mikek PS. * When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. see URL: http://www.dbsinstall.com/broadcast/vhf_uhf_freq_list.asp 41 is 324 - 330MHz and 42 is 330-336 MHz cables attenuate more at higher frequency. By ALL means, if you're going to add an amplifier, add it at the source location, not at the receiver location Cheap, but good, ones are available from microcircuits. Can you buy a line driver from your CATV company? I suspect the 'better' cable is only marginally better. What is the EXACT cable you're using? what is its attenuation per foot per MHz? You can buy extremely low loss coax, but you may have to send in your first born. Go to a local NRTL [EMC Test Lab] and see if they can (are willing to) order a length for you. Find the highest channel you wish to receive and the frequency associated with that. Now you can balance the amplifier gain with the cable loss to determine if it will work. Note you already know that 170 ft of ?? cable gets you up to channel 41, so from that number you can estimate just how much drop your receiver can take before it stops receiving. |
#6
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On 2/8/2012 11:00 AM, amdx wrote:
Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. Are you sure it's a signal strength problem? The cable guy should have been able to measure the signal at your cable box. Are the people using the other taps having problems? If you're on a boat, you might be at the end of the cable run. In that case, you might be able to get them to crank up the gain in their distribution amp. Power at the pole is not a problem. You can get amps that are powered through the signal cable to your cable box. Getting them to let you install it is another matter. You can get MUCH better wire, for a price. Signal strength is not the only problem with digital TV. Reflections in the system can confuse the decoder. Are there any unterminated cables on the other taps? I have OTA antenna digital TV. Plenty of signal, but reflections cause significant drop outs on some channels. More signal won't fix that. In fact, I have a variable attenuator to REDUCE signal strength. I tweak the signal level for fewest dropouts. Might be electrical noise coupled in thru the ground system. Bottom line is that you pay the cable company for TV reception. It's their responsibility to provide you with a watchable signal. You shouldn't have to tell them what to do. They should just FIX it!! |
#7
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On 2/8/2012 2:17 PM, Ian Jackson wrote:
In message , amdx writes Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. Despite your long 170ft drop cable, were you getting good analogue signals before the change to digital? If so, it could be that something is not right. Normally, even if you have had only fairly mediocre analogues, the digitals are good. But, analog can be snowy but very watchable, digital an be pixalated and stuttering without no sound or often no picture at all. Otherwise.... It sounds like your signals are just too weak. As things are, and if you can, the obvious fix would be to overcome the substantial loss of the 170ft drop cable by fitting an amplifier at or near the utility post (not at your end), and power it with low voltage via the coax from your end (ie similar to a line-powered masthead antenna amplifier). However, you would need to consult with the cable company to see if they were OK with letting you do this. It could be that they might be able advise you on the most suitable amplifier to use. It's not rocket science, but you have to be a little careful not to break any of their rules and generally do anything they don't approve of. I had not thought about a coax powered amp, Thanks. Mikek |
#8
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On 2/8/2012 2:36 PM, Fred Bloggs wrote:
On Feb 8, 2:00 pm, wrote: Hi All, I'm on a boat, about 170ft from the utility post. That's about 10dB loss at midband for RG6. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That was just a 3dB boost. But that 3bd did get me a more consistent picture. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. |
#9
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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In message , amdx
writes On 2/8/2012 2:17 PM, Ian Jackson wrote: In message , amdx writes Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. Despite your long 170ft drop cable, were you getting good analogue signals before the change to digital? If so, it could be that something is not right. Normally, even if you have had only fairly mediocre analogues, the digitals are good. But, analog can be snowy but very watchable, digital an be pixalated and stuttering without no sound or often no picture at all. You are quite correct. However, digital is generally capable of working to lower signal levels than analogue. It's amazing how rubbishy digital signals can be, yet still give perfect pictures - but don't expect miracles! Otherwise.... It sounds like your signals are just too weak. As things are, and if you can, the obvious fix would be to overcome the substantial loss of the 170ft drop cable by fitting an amplifier at or near the utility post (not at your end), and power it with low voltage via the coax from your end (ie similar to a line-powered masthead antenna amplifier). However, you would need to consult with the cable company to see if they were OK with letting you do this. It could be that they might be able advise you on the most suitable amplifier to use. It's not rocket science, but you have to be a little careful not to break any of their rules and generally do anything they don't approve of. I had not thought about a coax powered amp, Thanks. Mikek I see that several others have also suggested a coax-powered amplifier. [If the cable company can't give you more signal level, it's the only solution.] As suggested, they should be able to provide a suitable amplifier and power unit - or at least advise you what to use. -- Ian |
#10
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On 2/8/2012 2:47 PM, Dave Platt wrote:
In , wrote: I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Adding an amp at the cable box isn't all that likely to work... you can try it, but don't get your hopes up. Unless the amp has a significantly lower "noise figure" than the RF front end in the cable box, all you'll be doing is adding noise... the desired signal will be stronger, but the noise will be stronger yet. Something you could do, is add a single-port RF amplifier right at the utility post splitter, where your tap comes off of the feed. You can buy amplifiers of this sort which are designed to receive "phantom power" through the coax cable... you'd install a "power injector" at your boat, which feeds a DC voltage up the coax to the amplifier. This is probably your best bet: - It would amplify the signal before it's attenuated by the 170-foot cable run. - It won't require a power supply at the post... just at your boat, where you already have power. - It shouldn't interfere with the other taps on the splitter, even when the amplifier is not receiving power from your boat. You'd be looking for an "antenna mast" type of preamplifier. The Channel Master 0068DSB or 7777, Winegard AP-8700 or AP-8275 or HDP-269, AntennaCraft 10G212, or one of the Blonder Tongue Galaxy III models might do the job for you. You'll probably want a "75 ohm in, 75 ohm out" model, which would connect directly to the 75-ohm coax. Hey thanks for the part numbers, I'll look into these. Mikek |
#11
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On Wed, 8 Feb 2012 20:17:11 +0000, Ian Jackson
wrote: In message , amdx writes Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. Despite your long 170ft drop cable, were you getting good analogue signals before the change to digital? If so, it could be that something is not right. Normally, even if you have had only fairly mediocre analogues, the digitals are good. Otherwise.... It sounds like your signals are just too weak. As things are, and if you can, the obvious fix would be to overcome the substantial loss of the 170ft drop cable by fitting an amplifier at or near the utility post (not at your end), and power it with low voltage via the coax from your end (ie similar to a line-powered masthead antenna amplifier). However, you would need to consult with the cable company to see if they were OK with letting you do this. It could be that they might be able advise you on the most suitable amplifier to use. It's not rocket science, but you have to be a little careful not to break any of their rules and generally do anything they don't approve of. The cable company probably has amplifiers that can be powered over the cable run. If not, those amps can be found on ebay. Be sure to get a bidirectional amplifier because some systems send the control signals back up the cable to the cable company (Comcast in the southeastern US, for example.) John |
#12
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On 2/8/2012 3:03 PM, Robert Macy wrote:
On Feb 8, 12:00 pm, wrote: Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. see URL: http://www.dbsinstall.com/broadcast/vhf_uhf_freq_list.asp That's helpful. however, I do receive channels up to 484! Dang, just noticed "Lesbo Euro Trash: Big Boobs" is on 502, but, it's pay per view. :-) 41 is 324 - 330MHz and 42 is 330-336 MHz cables attenuate more at higher frequency. I thought there might be a bigger jump between 41 and 42 because when 42 was pixelating 41 was always perfect. By ALL means, if you're going to add an amplifier, add it at the source location, not at the receiver location Cheap, but good, ones are available from microcircuits. Can you buy a line driver from your CATV company? I suspect the 'better' cable is only marginally better. What is the EXACT cable you're using? what is its attenuation per foot per MHz? You can buy extremely low loss coax, but you may have to send in your first born. Go to a local NRTL [EMC Test Lab] and see if they can (are willing to) order a length for you. I think I'll try the amp, before spending for better cable. I think I just found a work around, The station I wanted, 42 is repeated on 428 in HD and it doesn't pixelate when 42 does. The pixelating problem is rare, only a spall percentage of the time, but very annoying. Ah, the wonderful world if Digital TV. Mikek |
#13
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On 2/8/2012 3:12 PM, mike wrote:
On 2/8/2012 11:00 AM, amdx wrote: Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. Are you sure it's a signal strength problem? Yes, it is the loss in the cable. The cable guy should have been able to measure the signal at your cable box. Are the people using the other taps having problems? No other problems, I'm just way down the dock from them. If you're on a boat, you might be at the end of the cable run. In that case, you might be able to get them to crank up the gain in their distribution amp. Next time they are around I'll ask. Power at the pole is not a problem. You can get amps that are powered through the signal cable to your cable box. Getting them to let you install it is another matter. You can get MUCH better wire, for a price. Signal strength is not the only problem with digital TV. Reflections in the system can confuse the decoder. Are there any unterminated cables on the other taps? Yes that is possible, There are transients in and out so sometimes the taps are used and sometimes not. I suppose I could make a bunch of 75 ohm terminations, and put on a new one every time it's needed. However I never noticed a correlation between boats in and boats out. I have OTA antenna digital TV. Plenty of signal, but reflections cause significant drop outs on some channels. More signal won't fix that. In fact, I have a variable attenuator to REDUCE signal strength. I tweak the signal level for fewest dropouts. Might be electrical noise coupled in thru the ground system. Bottom line is that you pay the cable company for TV reception. It's their responsibility to provide you with a watchable signal. You shouldn't have to tell them what to do. They should just FIX it!! Ya, but no. It's in a marina and the marina has a deal with the cable company. At this point there is talk about putting up an antenna. The marina has ten cable boxes for transients that need to be plugged in and connected (I guess keep them updated). So it has become a hassle for the marina handle the boxes. I just want to lay low and not rock the boat. |
#14
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![]() "amdx" wrote in message ... Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek At only 170 feet, that should not be a problem. My cable runs down a utility post, then over 200 feet to my house. It goes to a 2 way spitter and then about 30 feet to a cable modem. The other end goes to anotehr two way splitter, one side to a regular TV and the other to a digital box. No problem with the TV signal at my house, and the internet is around 7 MB or however they measuer it. That is by my test on the internet and what they say I am paying for in the speed./ Sounds like they need to send more signal from the main cable to the taps to your line. |
#15
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On Feb 8, 2:18*pm, amdx wrote:
On 2/8/2012 3:03 PM, Robert Macy wrote: On Feb 8, 12:00 pm, *wrote: Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. * *That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. * * I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. * *Getting anymore from the cable company is not an option. * * Any ideas to get a better signal? * * * * * * * * *Mikek PS. * *When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. see URL: http://www.dbsinstall.com/broadcast/vhf_uhf_freq_list.asp * *That's helpful. however, I do receive channels up to 484! Dang, just noticed "Lesbo Euro Trash: Big Boobs" is on 502, but, it's pay per view. :-) 41 is 324 - 330MHz and 42 is 330-336 MHz cables attenuate more at higher frequency. * I thought there might be a bigger jump between 41 and 42 because when 42 was pixelating 41 was always perfect. By ALL means, if you're going to add an amplifier, add it at the source location, not at the receiver location Cheap, but good, ones are available from microcircuits. Can you buy a line driver from your CATV company? I suspect the 'better' cable is only marginally better. What is the EXACT cable you're using? what is its attenuation per foot per MHz? You can buy extremely low loss coax, but you may have to send in your first born. *Go to a local NRTL [EMC Test Lab] and see if they can (are willing to) order a length for you. * *I think I'll try the amp, before spending for better cable. I think I just found a work around, The station I wanted, 42 is repeated on 428 in HD and it doesn't pixelate when 42 does. * The pixelating problem is rare, only a spall percentage of the time, but very annoying. Ah, the wonderful world if Digital TV. * * * * * * * * *Mikek- Hide quoted text - - Show quoted text - FWIW, our local cable system just converterd to digital and after installing the cable boxes I noticed that there were usually about 4-6 drop-outs between 6PM and 11PM. I suspected that the problem was at their end but they sent out a tech who re-terminated the cables at the demarcation box outside then changed that splitter from 3 output to 2 output. Inside he trimmed about 2m of excess cable from the wall jack [inside the wall space] and re-terminated that and installed a new jumper from there to a splitter [replaced] feeding the two cable boxes, one feeding the TV the other the VCR. He then measured the levels and the incoming signal was -10dB [just on nominal] and the back feed level [at the cable office] was -15dB, again just on nominal. He said that performance was good down to at least -20dB incoming. My run is about the same length as yours from the distribution pedistal and is of lower performance that RG-6. The number of drop-outs is perhaps slightly less, but a new PVR seems to handle the drop-outs much better than the cable boxes did so they are less noticable than before. I have also noted that one particular commercial has a drop-out in it and it is the same everytime it is run, again pointing to the problem being at their end. Neil S |
#16
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On Wed, 08 Feb 2012 13:00:12 -0600, amdx wrote:
I'm on a boat, about 170ft from the utility post. Ok, 200ft of coax. Presumably RG6a/u. Recently our cable company switched to the wonderful world of Digital TV. You have been assimilated. Resistance is futile. I got the new digital converter and had no picture. Something is wrong. The nominal signal from the cable drop is suppose to be 0dBm. If there's a splitter involved, they like to crank it up to about 10dBm. Your 200ft of RG6a/u will drop the signal from between 4dB at the low end, to about 6dB at the high end. Your set top box is suppose to operate with a 10dB margin. If you would kindly disclose the maker and model, it might be possible to find the specs. Typically, you'll have at least 10dB margin. Even with 200ft of coax, you should have 4 to 6dB margin. Drag your cable box and TV over to the splitter and try it on the incoming drop. If that works, move to the ports on the splitter. Make sure that the unused ports are terminated properly. If that doesn't work, call your unfriendly cable company and ask them why they don't have sufficient level to operate your set top box without the 200ft cable. If it does work, find a 200ft RG6a/u cable that isn't saturated with water. Try to get some compressing fittings instead of the crappy crimp type. Your unspecified cable set top box may also have some user accessible diagnostics which include per channel signal levels. You may want to check those. I'm not familiar with Knology, but I suspect they do the same thing as Comcast. With Comcast, the lower 72 channels are still analog in my area. If so, you can probably plug your TV directly into the cable, set the TV for cable frequencies, not broadcast, and see if that still plays. Hint: Troubleshoot by substitution. Drivel: I spent about an hour troubleshooting my TV distribution system, only to find a brand new Type F "barrel" connector, with no center connections. That which is most obviously correct, beyond any need of checking, is usually the problem. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
#17
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All the technical advice is fine. However none of this is necessary.
Just call the cable company and tell them that the situation is unacceptable so you are cancelling. Voila ! Next day dBs ! J |
#18
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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![]() "amdx" wrote in message ... Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. snip Getting anymore from the cable company is not an option. I take respectful exception to that last sentence. My digital cable box is about 130 cable-feet from the pole. My signal is tapped enroute for digital telephone, tapped enroute for Internet and then split (by me) so I can feed analog signals via a disttribution amp serving bedrooms, kitchen and shack. I get enough from the pole tap to do the job. Somebody is treating you badly -- maybe the cable company, maybe the marina. Yes, the approach for you to buy and install an inline, remote-power amp at the pole is entirely valid, technically. However, that's not in keeping with reasonable expectations. You needn't roll over so easily. It's supposed to work. What -- Are you worried you might offend somebody? That "somebody" seems quite okay with kicking you in the ankle. Or elsewhere. "Sal" |
#19
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On Wed, 08 Feb 2012 15:41:08 -0800, Jeff Liebermann
wrote: Your 200ft of RG6a/u will drop the signal from between 4dB at the low end, to about 6dB at the high end. Some better numbers for RG6a/u: Freq Atten MHz -dB 10 0.8 50 1.4 100 2.9 200 4.3 400 6.4 1000 11.0 The CATV band is approximately 50 to 800MHz. With 200ft of cable, you should see 2.8 to 16dB of loss. While there may be problem at the high channels, all the lower channels should work. The 4 way splitter has a loss of about -7dB. Picking a random set top box: http://www.zoran.com/IMG/pdf/Simplify_NextGen_STBs_Solutions.pdf See Page 3. Sensitivity is -18dBm for 256QAM and -24dBm 64QAM. At the low end, you have 0dBm in, 7dB loss in the splitter, 2.8dB loss in the coax, resulting in -9.8dBm to the box. That's much more than the -18dBm/-24dBm needed. However, at the high end, things are not so wonderful. 0dbm in, 7dB loss in the splitter, and 16dB loss in the coax, which delivers -23dBm. That's 1dB of margin, which is not very good. Still, it should work on the lower channels. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
#20
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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amdx wrote:
Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. Looks like the cable guys screwed up. a. They should be putting enough signal on that cable to overcome the loss. b. They should be able to measure the amplitude of pilot signals at your end of the cable and tell you how much above minimums they are. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. If all else fails you may need an amp. What Fred means with drop amp is usually called a "mast preamplifier", like this: http://www.amazon.com/Uhf-Vhf-Antenn...748729&sr=8-20 I don't know this particular one but essentially it should be weather-proof. It gets its DC voltage via the coax, from a wall wart that would plug in at your boat. So no need to run a power supply cable up there. Don't go for too much gain. This dreaded DTV falls apart rather easily on the slightest distortion or cross-modulation. Not sure if the above amp can handle that. You might need a more expensive one. Michael Terrell might know which ones are good. What matters is dynamic range. Also, make sure you have a perfect 75ohms match at your end. The cable box from the cable company should provide that. if you have Internet and/or phone through them as well check that connection so it doesn't cause reflections. On a boat at sea stuff can corrode quickly. Oh, and don't dare to watch that boobs channel while your wife's on the boat :-) -- Regards, Joerg http://www.analogconsultants.com/ |
#21
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On 2/8/2012 5:41 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 13:00:12 -0600, wrote: I'm on a boat, about 170ft from the utility post. Ok, 200ft of coax. Presumably RG6a/u. Recently our cable company switched to the wonderful world of Digital TV. You have been assimilated. Resistance is futile. I got the new digital converter and had no picture. Something is wrong. The nominal signal from the cable drop is suppose to be 0dBm. If there's a splitter involved, they like to crank it up to about 10dBm. Your 200ft of RG6a/u will drop the signal from between 4dB at the low end, to about 6dB at the high end. Your set top box is suppose to operate with a 10dB margin. If you would kindly disclose the maker and model, it might be possible to find the specs. Typically, you'll have at least 10dB margin. Even with 200ft of coax, you should have 4 to 6dB margin. Now remember the problem is quite intermittent, but seems to be happening almost daily for short periods. Drag your cable box and TV over to the splitter and try it on the incoming drop. If that works, move to the ports on the splitter. Make sure that the unused ports are terminated properly. If that doesn't work, call your unfriendly cable company and ask them why they don't have sufficient level to operate your set top box without the 200ft cable. If it does work, find a 200ft RG6a/u cable that isn't saturated with water. Try to get some compressing fittings instead of the crappy crimp type. There should be no water in the cable, it's only a couple of months old and both ends have crimp on connectors and are located in a box or boat. Your unspecified cable set top box may also have some user accessible diagnostics which include per channel signal levels. You may want to check those. It does have diagnostics, I'm not sure if it is each channel though. But I can get some info out of the box. I'll be there Friday and I'll get that info and the model of the cable set top box. I'm not familiar with Knology, but I suspect they do the same thing as Comcast. With Comcast, the lower 72 channels are still analog in my area. If so, you can probably plug your TV directly into the cable, set the TV for cable frequencies, not broadcast, and see if that still plays. I'm using Comcast at the boat. We are lucky here (I think) in that we have a choice of two cable companies. Hint: Troubleshoot by substitution. Drivel: I spent about an hour troubleshooting my TV distribution system, only to find a brand new Type F "barrel" connector, with no center connections. That which is most obviously correct, beyond any need of checking, is usually the problem. Drivel is good. |
#22
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On 2/8/2012 6:38 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 15:41:08 -0800, Jeff wrote: Your 200ft of RG6a/u will drop the signal from between 4dB at the low end, to about 6dB at the high end. Some better numbers for RG6a/u: Freq Atten MHz -dB 10 0.8 50 1.4 100 2.9 200 4.3 400 6.4 1000 11.0 The CATV band is approximately 50 to 800MHz. With 200ft of cable, you should see 2.8 to 16dB of loss. While there may be problem at the high channels, all the lower channels should work. Any idea where channel 428 would be in that frequency range? That's a duplicate of 4,2 but in HD, and it works when 42 doesn't. The 4 way splitter has a loss of about -7dB. Just a point. I may not have made it clear. I had the tech put in two 2way splitters and connect me to the first one. Hoping to gain 3db. (or 4) and it did make a difference. Picking a random set top box: http://www.zoran.com/IMG/pdf/Simplify_NextGen_STBs_Solutions.pdf See Page 3. Sensitivity is -18dBm for 256QAM and -24dBm 64QAM. At the low end, you have 0dBm in, 7dB loss in the splitter, 2.8dB loss in the coax, resulting in -9.8dBm to the box. That's much more than the -18dBm/-24dBm needed. However, at the high end, things are not so wonderful. 0dbm in, 7dB loss in the splitter, and 16dB loss in the coax, which delivers -23dBm. That's 1dB of margin, which is not very good. Still, it should work on the lower channels. |
#23
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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On 2/8/2012 7:01 PM, Joerg wrote:
amdx wrote: Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. Looks like the cable guys screwed up. a. They should be putting enough signal on that cable to overcome the loss. b. They should be able to measure the amplitude of pilot signals at your end of the cable and tell you how much above minimums they are. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. If all else fails you may need an amp. What Fred means with drop amp is usually called a "mast preamplifier", like this: http://www.amazon.com/Uhf-Vhf-Antenn...748729&sr=8-20 I don't know this particular one but essentially it should be weather-proof. It gets its DC voltage via the coax, from a wall wart that would plug in at your boat. So no need to run a power supply cable up there. Don't go for too much gain. This dreaded DTV falls apart rather easily on the slightest distortion or cross-modulation. Not sure if the above amp can handle that. You might need a more expensive one. Michael Terrell might know which ones are good. What matters is dynamic range. Also, make sure you have a perfect 75ohms match at your end. The cable box from the cable company should provide that. if you have Internet and/or phone through them as well check that connection so it doesn't cause reflections. On a boat at sea stuff can corrode quickly. Oh, and don't dare to watch that boobs channel while your wife's on the boat :-) Been trying to think of something funny to say about that... Best I got is, she would say, "mine look better than those! |
#24
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amdx wrote:
On 2/8/2012 6:38 PM, Jeff Liebermann wrote: On Wed, 08 Feb 2012 15:41:08 -0800, Jeff wrote: Your 200ft of RG6a/u will drop the signal from between 4dB at the low end, to about 6dB at the high end. Some better numbers for RG6a/u: Freq Atten MHz -dB 10 0.8 50 1.4 100 2.9 200 4.3 400 6.4 1000 11.0 The CATV band is approximately 50 to 800MHz. With 200ft of cable, you should see 2.8 to 16dB of loss. While there may be problem at the high channels, all the lower channels should work. Any idea where channel 428 would be in that frequency range? That's a duplicate of 4,2 but in HD, and it works when 42 doesn't. I believe that's entirely up to the cable company, you'd have to ask an engineer there. http://en.wikipedia.org/wiki/Digital_cable Quote "For example, a cable company might call channel 5-1 "channel 732" and channel 5-2 "channel 733"". The 4 way splitter has a loss of about -7dB. Just a point. I may not have made it clear. I had the tech put in two 2way splitters and connect me to the first one. Hoping to gain 3db. (or 4) and it did make a difference. Where does the other leg of that splitter go to? And is that end properly terminated? [...] -- Regards, Joerg http://www.analogconsultants.com/ |
#25
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On Wed, 08 Feb 2012 19:24:06 -0600, amdx
wrote: Now remember the problem is quite intermittent, but seems to be happening almost daily for short periods. Monitor the signal levels at the set top box and see if it coincides with something nearby changing, such as the dock lights or operation of heavy machinery. Maybe shove a DVM (digital voltmeter) into the AC power and see if it moves around. There should be no water in the cable, it's only a couple of months old and both ends have crimp on connectors and are located in a box or boat. I don't like crimp type connectors. Push on connectors are MUCH better. Also, if the coax came from Radio Shack, all bets are off as to the quality. It does have diagnostics, I'm not sure if it is each channel though. But I can get some info out of the box. I'll be there Friday and I'll get that info and the model of the cable set top box. Digital set top box diagnostics are different from analog. Instead of per-channel levels, it might have levels for specific channels. I'm using Comcast at the boat. We are lucky here (I think) in that we have a choice of two cable companies. If it's Comcast, you will probably still have the lower 72 channels doing analog. Remove the set top box and plug in your TV directly. Drivel is good. The story of my life. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
#26
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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![]() Just a point. I may not have made it clear. I had the tech put in two 2way splitters and connect me to the first one. Hoping to gain 3db. (or 4) and it did make a difference. Where does the other leg of that splitter go to? And is that end properly terminated? [...] -- Regards, Joerg http://www.analogconsultants.com/ right good question...OP, when you had the analog signal, was there significant ghosting? digital boxes might tolerate a WEAK signal but they are intolerant of reflections. Mark |
#27
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Posted to sci.electronics.repair,rec.radio.amateur.antenna,sci.electronics.design
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amdx wrote:
On 2/8/2012 7:01 PM, Joerg wrote: amdx wrote: Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. Looks like the cable guys screwed up. a. They should be putting enough signal on that cable to overcome the loss. b. They should be able to measure the amplitude of pilot signals at your end of the cable and tell you how much above minimums they are. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. If all else fails you may need an amp. What Fred means with drop amp is usually called a "mast preamplifier", like this: http://www.amazon.com/Uhf-Vhf-Antenn...748729&sr=8-20 I don't know this particular one but essentially it should be weather-proof. It gets its DC voltage via the coax, from a wall wart that would plug in at your boat. So no need to run a power supply cable up there. Don't go for too much gain. This dreaded DTV falls apart rather easily on the slightest distortion or cross-modulation. Not sure if the above amp can handle that. You might need a more expensive one. Michael Terrell might know which ones are good. What matters is dynamic range. Also, make sure you have a perfect 75ohms match at your end. The cable box from the cable company should provide that. if you have Internet and/or phone through them as well check that connection so it doesn't cause reflections. On a boat at sea stuff can corrode quickly. Oh, and don't dare to watch that boobs channel while your wife's on the boat :-) Been trying to think of something funny to say about that... Best I got is, she would say, "mine look better than those! And you know what you'd better reply! Cheers Phil Hobbs |
#28
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On 2/8/12 7:27 PM, Sal wrote:
wrote in message ... Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. snip Getting anymore from the cable company is not an option. I take respectful exception to that last sentence. My digital cable box is about 130 cable-feet from the pole. My signal is tapped enroute for digital telephone, tapped enroute for Internet and then split (by me) so I can feed analog signals via a disttribution amp serving bedrooms, kitchen and shack. I get enough from the pole tap to do the job. I respectfully agree! 8^) I don't know exactly how it's done now, but when I worked in the Cable industry many moons ago, we had a lot of adjustment we could make. Even more, we had variable by frequency attenuators so we could ensure that a flat signal showed up. There was a lot of signal at the amplifiers, and if we really needed more oomph, we could put in a distribution amp. Another amp was really rare. Somebody is treating you badly -- maybe the cable company, maybe the marina. Yes, the approach for you to buy and install an inline, remote-power amp at the pole is entirely valid, technically. However, that's not in keeping with reasonable expectations. You needn't roll over so easily. It's supposed to work. What -- Are you worried you might offend somebody? That "somebody" seems quite okay with kicking you in the ankle. Or elsewhere. Yeah, there is something wrong there. For as much as people hate Comcast, when I had cable internet put in, they replaced all the cable from the pole to the house, and a lot inside the house. I did talk them out of replacing the new cable I had put in, but insisted on putting new connectors on them. The measured all the levels and set them high enough that I'd be able to add more televisions if I liked. Time to call the cable company and tell them you want your MTV. - 73 de Mike N3LI - |
#29
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On Wed, 08 Feb 2012 19:30:07 -0600, amdx
wrote: Any idea where channel 428 would be in that frequency range? That's a duplicate of 4,2 but in HD, and it works when 42 doesn't. Ummm... it's ugly. There are up to 10 standard definition or 2 HD channels crammed into a 6 MHz wide RF slot. In order to untangle this, you would need to run a PSIP decoder and extract the CVCT record: http://en.wikipedia.org/wiki/PSIP to figure out where digital CH 428 fits. It could literally be anywhere. However, if you happen to have an tuneable notch filter (which I happen to have), you can stuff it in series with the cable, and spin the dial until the signal disappears. Then, just read the dial. (Comcast seems to be putting well paying and popular channels on the lower frequencies, and obscure junk on the higher frequencies. I'm not sure if this is intentional, accidental, or my imagination). The 4 way splitter has a loss of about -7dB. Just a point. I may not have made it clear. I had the tech put in two 2way splitters and connect me to the first one. Hoping to gain 3db. (or 4) and it did make a difference. Yeah, I saw that. I guess I wasn't too clear. The input signal can vary over a 10-16dB range, and it still should work. The 3dB difference between a two port and a 4 port splitter isn't going to make much difference, exept at the higher channels. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com # http://www.LearnByDestroying.com AE6KS |
#30
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![]() "Michael Coslo" wrote in message ... snip Time to call the cable company and tell them you want your MTV. No way to know from here, but they may not be able to add another amp. While I was looking for something else, I lurched into this page: http://www.cisco.com/en/US/products/hw/cable/ps2217/products_white_paper0900aecd800fc94c.shtml While its intended audience is Internet modem designers, the noise discussions are informative with regard to other signals, too. My point: When you try stringing too many amps in line, the signal-to-noise ratio (SNR) eventually becomes unacceptable. (Remember the acceptable SNRs cited for 256 QAM and 64 QAM.) "Sal" |
#31
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![]() "Sal" wrote in message ... My point: When you try stringing too many amps in line, the signal-to-noise ratio (SNR) eventually becomes unacceptable. (Remember the acceptable SNRs cited for 256 QAM and 64 QAM.) "Sal" Sorry. I should have said carrier to noise ratio (CNR), not SNR. SNR applies to post-detection signals. i joined the digital world late in life. "Sal" |
#32
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amdx wrote:
Hi All, I'm on a boat, about 170ft from the utility post. Recently our cable company switched to the wonderful world of Digital TV. I got the new digital converter and had no picture. I took the box back and got a second box, still no picture. So now I suspect a weak signal and confirm that it is the cable length. The cable company came out and gave me a better cable than I had installed. At this point I have a picture but it is intermittent. The signal at the utility post has 3 outputs and had a four way splitter, I suggested the cable guy put in two 2 way splitters and give me the stronger (first) tap. That got my signal to work almost all the time. I'd like to get the signal to work 100% of the time. I don't has access to electricity at the utility post, so an amp is out. Although I could try an amp at the cable box end. Is that reasonable? I would run two cables if there was a way to make it increase signal strength. Getting anymore from the cable company is not an option. Any ideas to get a better signal? Mikek PS. When the signal fails it seems channel 41 is ok and above 42 it breaks up. Curious to know if there is an unusual frequency jump between those two digital channels. Well, you could add an amplifier at the splitter where (nominally) there is no power. Use the coax center conductor for power; inline capacitors allow signal to pass and feeding center via small choke allows DC but no signal. Once upon a time there were little adapters that did this AC/DC thing... |
#33
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In message , Jeff Liebermann
writes Something is wrong. The nominal signal from the cable drop is suppose to be 0dBm. If there's a splitter involved, they like to crank it up to about 10dBm. Careful! Don't get your dBm mixed up with your dBmV. There's around 48dB difference! 0dBm is a massive 48dBmV. That would certainly make most set-top boxes wake up and pay attention! -- Ian |
#34
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On 2/8/2012 7:50 PM, Joerg wrote:
amdx wrote: On 2/8/2012 6:38 PM, Jeff Liebermann wrote: On Wed, 08 Feb 2012 15:41:08 -0800, Jeff wrote: Your 200ft of RG6a/u will drop the signal from between 4dB at the low end, to about 6dB at the high end. Some better numbers for RG6a/u: Freq Atten MHz -dB 10 0.8 50 1.4 100 2.9 200 4.3 400 6.4 1000 11.0 The CATV band is approximately 50 to 800MHz. With 200ft of cable, you should see 2.8 to 16dB of loss. While there may be problem at the high channels, all the lower channels should work. Any idea where channel 428 would be in that frequency range? That's a duplicate of 4,2 but in HD, and it works when 42 doesn't. I believe that's entirely up to the cable company, you'd have to ask an engineer there. http://en.wikipedia.org/wiki/Digital_cable Quote "For example, a cable company might call channel 5-1 "channel 732" and channel 5-2 "channel 733"". The 4 way splitter has a loss of about -7dB. Just a point. I may not have made it clear. I had the tech put in two 2way splitters and connect me to the first one. Hoping to gain 3db. (or 4) and it did make a difference. Where does the other leg of that splitter go to? And is that end properly terminated? [...] They go to two other outlets, that are used for transient boaters. sometimes they are used and sometimes they sit unterminated. I have not seen my problem better or worse when boats are in or out. But I have several 75 ohm F connector terminations. It's worth a try. Mikek |
#35
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On 2/8/2012 8:21 PM, Mark wrote:
Just a point. I may not have made it clear. I had the tech put in two 2way splitters and connect me to the first one. Hoping to gain 3db. (or 4) and it did make a difference. Where does the other leg of that splitter go to? And is that end properly terminated? [...] -- Regards, Joerg http://www.analogconsultants.com/ right good question...OP, when you had the analog signal, was there significant ghosting? digital boxes might tolerate a WEAK signal but they are intolerant of reflections. Mark Never noticed any ghosting with the analog. Mikek |
#36
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On 2/8/2012 8:18 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 19:24:06 -0600, wrote: Now remember the problem is quite intermittent, but seems to be happening almost daily for short periods. Monitor the signal levels at the set top box and see if it coincides with something nearby changing, such as the dock lights or operation of heavy machinery. Maybe shove a DVM (digital voltmeter) into the AC power and see if it moves around. There should be no water in the cable, it's only a couple of months old and both ends have crimp on connectors and are located in a box or boat. I don't like crimp type connectors. Push on connectors are MUCH better. Also, if the coax came from Radio Shack, all bets are off as to the quality. I'm sorry I got that wrong, they are F compression connectors. Coax was from the cable company. My drivel: At my home, knology recently upgraded there system for faster internet. A cableman said he heard me radiating a block away. he came in and changed 7 crimp type connectors in my attic a couple of cable runs. Speedtest.com went from 6 Mbps to over 11 Mbps with just those changes. It does have diagnostics, I'm not sure if it is each channel though. But I can get some info out of the box. I'll be there Friday and I'll get that info and the model of the cable set top box. Digital set top box diagnostics are different from analog. Instead of per-channel levels, it might have levels for specific channels. I'm using Comcast at the boat. We are lucky here (I think) in that we have a choice of two cable companies. If it's Comcast, you will probably still have the lower 72 channels doing analog. Remove the set top box and plug in your TV directly. Oh, if that is the fact, I may get me some browny points, If I can get the signal up to snuff, then put the vcr back in the line, my wife could record her soaps again. That would get me 15 seconds of hero status! Mikek Drivel is good. The story of my life. |
#37
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On 2/9/2012 7:43 AM, amdx wrote:
On 2/8/2012 8:18 PM, Jeff Liebermann wrote: On Wed, 08 Feb 2012 19:24:06 -0600, wrote: Now remember the problem is quite intermittent, but seems to be happening almost daily for short periods. Monitor the signal levels at the set top box and see if it coincides with something nearby changing, such as the dock lights or operation of heavy machinery. Maybe shove a DVM (digital voltmeter) into the AC power and see if it moves around. There should be no water in the cable, it's only a couple of months old and both ends have crimp on connectors and are located in a box or boat. I don't like crimp type connectors. Push on connectors are MUCH better. Also, if the coax came from Radio Shack, all bets are off as to the quality. I'm sorry I got that wrong, they are F compression connectors. Coax was from the cable company. My drivel: At my home, knology recently upgraded there system for faster internet. A cableman said he heard me radiating a block away. he came in and changed 7 crimp type connectors in my attic a couple of cable runs. Speedtest.com went from 6 Mbps to over 11 Mbps with just those changes. It does have diagnostics, I'm not sure if it is each channel though. But I can get some info out of the box. I'll be there Friday and I'll get that info and the model of the cable set top box. Digital set top box diagnostics are different from analog. Instead of per-channel levels, it might have levels for specific channels. I'm using Comcast at the boat. We are lucky here (I think) in that we have a choice of two cable companies. If it's Comcast, you will probably still have the lower 72 channels doing analog. Remove the set top box and plug in your TV directly. Oh, if that is the fact, I may get me some browny points, If I can get the signal up to snuff, then put the vcr back in the line, my wife could record her soaps again. That would get me 15 seconds of hero status! Mikek Just an addition to the termination debate, the marina has about 150 taps, I'd be surprised if 30 of them are connected to a tv and the rest are unterminated. The line generally goes to the utility pedestal into a 2 way splitter and then about 1 ft of cable connects it to the 2 taps for the boat owners. Mikek |
#38
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amdx wrote:
On 2/8/2012 7:50 PM, Joerg wrote: amdx wrote: On 2/8/2012 6:38 PM, Jeff Liebermann wrote: On Wed, 08 Feb 2012 15:41:08 -0800, Jeff wrote: Your 200ft of RG6a/u will drop the signal from between 4dB at the low end, to about 6dB at the high end. Some better numbers for RG6a/u: Freq Atten MHz -dB 10 0.8 50 1.4 100 2.9 200 4.3 400 6.4 1000 11.0 The CATV band is approximately 50 to 800MHz. With 200ft of cable, you should see 2.8 to 16dB of loss. While there may be problem at the high channels, all the lower channels should work. Any idea where channel 428 would be in that frequency range? That's a duplicate of 4,2 but in HD, and it works when 42 doesn't. I believe that's entirely up to the cable company, you'd have to ask an engineer there. http://en.wikipedia.org/wiki/Digital_cable Quote "For example, a cable company might call channel 5-1 "channel 732" and channel 5-2 "channel 733"". The 4 way splitter has a loss of about -7dB. Just a point. I may not have made it clear. I had the tech put in two 2way splitters and connect me to the first one. Hoping to gain 3db. (or 4) and it did make a difference. Where does the other leg of that splitter go to? And is that end properly terminated? [...] They go to two other outlets, that are used for transient boaters. sometimes they are used and sometimes they sit unterminated. I have not seen my problem better or worse when boats are in or out. But I have several 75 ohm F connector terminations. It's worth a try. Yup, try it. Transient boaters will most likely not carry the required set top box around but use the lower analog channels or nowadays maybe UHF digital. Sort of "basic cable". Then the TV is connected directly and those rarely have a true 75ohms input. -- Regards, Joerg http://www.analogconsultants.com/ |
#39
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On Thu, 09 Feb 2012 07:54:19 -0600, amdx
wrote: My drivel: At my home, knology recently upgraded there system for faster internet. A cableman said he heard me radiating a block away. he came in and changed 7 crimp type connectors in my attic a couple of cable runs. Speedtest.com went from 6 Mbps to over 11 Mbps with just those changes. Yep, that's the way it works. Compression type F connectors work well. Crimp type are junk. The catch is that there are probably 100 different types of connectors, each with their own compression tools, intended to fit about 8 different types of 75 ohm coax (RG6a/u, RG59/u, single shielded, double shielded, quad shielded, direct burial, etc). Mixing connector types and cables doesn't work. I got fed up and "obtained" a 1000ft roll of double shielded RG6a/u, a big of matching F, BNC, and phono connectors, a compression tool, a stripping tool, and replaced all the junk cables in the house. If it's Comcast, you will probably still have the lower 72 channels doing analog. Remove the set top box and plug in your TV directly. Oh, if that is the fact, I may get me some browny points, If I can get the signal up to snuff, then put the vcr back in the line, my wife could record her soaps again. That would get me 15 seconds of hero status! Mikek I'm sure it's true for Comcast in Santa Cruz, CA. No clue on other areas. The grand plan is to move all the analog channels to digital area by area: http://www2.insidenova.com/news/2011/jun/22/comcast-removes-scores-channels-analog-cable-ar-1126652/ http://www2.newsadvance.com/business/2011/nov/09/comcast-switching-analog-digital-ar-1448489/ Unfortunately, your area may be one of those that have moved to all digital. Hard to tell from here. Just an addition to the termination debate, the marina has about 150 taps, I'd be surprised if 30 of them are connected to a tv and the rest are unterminated. The line generally goes to the utility pedestal into a 2 way splitter and then about 1 ft of cable connects it to the 2 taps for the boat owners. Mikek Can you determine if the marina is using a distribution amplifier driving a big splitter, or is using a single cable trunk snaked through the marina, with taps (directional couplers) at various points? If taps, it's easy to install too many taps, or miscalculate the tap type, resulting in level variations along the trunk. http://www.doityourself.com/forum/entertainment-center-tvs-stereos-vcrs-dvds-8-track-tape-players/334706-difference-between-tap-splitter.html -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#40
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On Thu, 09 Feb 2012 09:01:21 -0800, Jeff Liebermann
wrote: How to Check Comcast Signal Levels http://www.ehow.com/how_7777024_check-comcast-signal-levels.html I'm not sure if this works on the newer set top boxes, but give it a try. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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