JP1 Remotes Forum Index JP1 Remotes


FAQFAQ SearchSearch 7 days of topics7 Days MemberlistMemberlist UsergroupsUsergroups RegisterRegister
ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

OT: advice on running cables

 
Post new topic   Reply to topic    JP1 Remotes Forum Index -> JP1 - General Forum
View previous topic :: View next topic  
Author Message
johnsfine
Site Admin


Joined: 10 Aug 2003
Posts: 4767
Location: Bedford, MA

PostPosted: Wed Oct 08, 2003 3:06 pm    Post subject: Reply with quote

Topic drift but:

On my "to do" list is investigating A/V splitting in order to make it easier to tape with or without the digital cable box. I wasn't sure whether there would be signal loss issues. Does it require a special splitter or just the cheap Y connection that does it electrically?

Present absurd setup:
Cable enters house, goes through a special two way splitter, one side of which is the cable modem. Goes through a long cable and a three way splitter one side of which is digital cable box.

(the installer told us neither the long cable nor second splitter were permitted and were responsible for the horrid reception we got initially even though we got the same horrid reception when we moved the cable box to where cable enters the house and dropped the second and even the first splitter. Despite that he kept insisting the fact that we'd ever even tried that caused our bad reception until I finally convinced him to cut the 20 year old connector off the splice outside the house and crimp on a new one at which point reception became perfect). But anyway, any splitting beyond that second splitter seems to be splitting too much.

The other two sides of the three way go to a VCR (the only one which gets the top few analog channels clearly) and one input of a powered (amplifying) manual coax switch, which outputs to two more VCR's and one coax input of the TV (none of which get the high analog channels well). Then the coax output of the cable tuner gets split between another input of the switch and the other coax input of the TV. Finally the A/V output of the cable tuner goes to the fourth VCR.

My to do list includes trying splitting the A/V output so the first VCR can get it too and could switch electrically between analog (coax) and digital (A/V) input. Also my quick attempts at tapping one more device (4'th VCR) into the analog side also failed. Before or after the powered switch one more split seems to wreck analog reception for several devices vs. the present perfect digital and perfect analog for all but a few high channels on some devices. I have yet to experiment with puting back the signal amplifier I used before getting digital cable (before realizing all our reception problems were due to that bad connector outside). That worked very well at the point the coax entered the house, cleaned most of the problems caused by the connector outside and let me split however I wanted beyond it. But I can't use it there with digital cable and haven't had time to try it further in.
Back to top
View user's profile Send private message Send e-mail Visit poster's website
The Robman
Site Owner


Joined: 01 Aug 2003
Posts: 18131
Location: Chicago, IL

PostPosted: Wed Oct 08, 2003 4:28 pm    Post subject: Reply with quote

If the long stretch of cable is using cheap coax, I would recommend replacing it with higher quality shielded cable, especially if it's running outside. Also, splitters are not all created equal, make sure you're using good, shielded splitters. Plus of course, if any of the cable end connectors are in poor shape, replace them too.

Then, on the end of the long cable, rather than using a regular splitter, use an aplified splitting box. You can get them on the cheap side from Radio Shack ($15 to $20) which is where I got mine, but there are higher quality ones out there too.

That should improve things.

(Btw, I have a very similar setup. Where the cable reaches the house, it's split two ways, one way to a nearby TV, and the other way is a 100 foot external cable. At the end of that cable, I split it where one path goes to the cable modem and the other to an amplified splitting box, which distributes the signal to 2 ReplayTV units, a cable box and the TV).
_________________
Rob
www.hifi-remote.com
Please don't PM me with remote questions, post them in the forums so all the experts can help!
Back to top
View user's profile Send private message Visit poster's website
jon_armstrong
Expert


Joined: 03 Aug 2003
Posts: 1238
Location: R.I.P. 3/25/2005

PostPosted: Wed Oct 08, 2003 5:15 pm    Post subject: Reply with quote

John,

I may not have the solution, because my experiences have come from trying to get a UHF signal from Baltimore (I live just outside Washington DC) to get a high definition station. My HD receiver has a signal strength meter, and before I ran a RG6 cable (rather than the old existing RG-58 in my 20 year old house), it didn't even lock on. After that, it was a stable as and good the local stations and close to the same signal strength. Of course digital TV is binary, perfect or garbage.

So if you can pull in RG6 that should really make a difference, if you haven't done so already. It's pretty cheap so you could try laying it out on the floor and see if it makes a big difference before you go into the attic or wherever. BTW, I believe that the specs on the new digital cable splitters are are 5 to 900 MHz.

Every RF amplifier, switch, or splitter that I have ever purchased from RS seemed to degrade the higher frequency signals (more than other brands) but that is from the past since I never buy RF transmission stuff there anymore. But you can always try it and return it. (I don't think you want any amplifier between the feed and the cable modem.)

I also think you should try a 6-way or 8-way (if you need it) splitter rather than sequential splitters. I haven't exactly visualized your system and why it is done the way it is, so the six-way may not be a solution. You also probably have to pull in more cable.

So my bottom line advice is try the passive solution first, then amplify. I tried the amplifier with the old cable and it didn't work. Frankly, I was skeptical before this experience that RG-6 would make that much difference.

Finally, is it possible that one VCR is pulling down the rest of the system because it is defective or has degraded insulation? You might try by systematically unhooking each VCR. Also terminating resistors in unused ports? It sure made a difference in the old coax based Ethernet systems.

PS. I hadn't seen Rob's post since I got interrupted while posting this so I did not intend to refute Rob's more recent experience with RS gear Smile
_________________
-Jon
Back to top
View user's profile Send private message Send e-mail Visit poster's website
jamesgammel
Exile Island Resident


Joined: 03 Aug 2003
Posts: 397
Location: Gillette, Wyoming

PostPosted: Wed Oct 08, 2003 5:34 pm    Post subject: Reply with quote

Since you mentioned "cheap Y's" and A/V signals I assume you mean the regular yellow/red/white. For lowest loss, go with the heavier coax type shielded cables. Most times these are made with RG-59 coax cable. They are better than the skinny "cheap microphone"type cable in some really cheap "Y's".

Unless cable is double shielded (ie foil wrapped), the longer a cable is, the BOTH more signal loss you'll suffer, and the more "noise" it will pick up. So keep any and all cables as short as feasible.

You're better to amplify a cleaner, stronger signal than a weaker one that's picked up noise. Thus, The closer to the "source", the better and cleaner the amplification will work. In other words, you're better off to amplify a signal at the begionning of a run where the signal is stronger and cleaner than try to salvage a weak signal that's has noise introduced before it got there.

On a sat dish, or outside "over the air" broadcast signals, you're better off to amplify at the dish or antenna, rather than at the receiver or TV. If you use two, the best place for the first one is where the cable enters the house, then where it splits from the main room and goes to another room (where you have the long coax).

With a lot of splits and trying to input to so many devices, run the best coax you can afford. "Normal" RG-59U being the worst, RG-6 being better. Both are 75 ohm cables, but the RG-6 is better shielded.

Outside, if you have splitters/amplifiers, etc. use the "weather-proof" connectors (they have an O-ring at the base), and use a dielectric grease on the fittings. (found at most automotive stores). This will help with the weather sealing, and cut down on corrosion which will degrade signals over time. It doesn't hurt to use the dielectric grease indoors either.

Jim
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
johnsfine
Site Admin


Joined: 10 Aug 2003
Posts: 4767
Location: Bedford, MA

PostPosted: Wed Oct 08, 2003 6:06 pm    Post subject: Reply with quote

It's all in inaccessable locations, which is why I haven't experimented much. I certainly don't have access to pull any new cable. It all was run during a major remodeling when the whole ceiling and most of the walls were ripped up. I should have run more and better cable then, but it's too late to change now.

I don't want to risk degrading the cable modem, so I don't want to take out the first stage two way split. I tried 2, 4 and 5 way splitters as the second stage, all of which had been used without problems before I got digital cable and cable modem. The 4 and 5 way split had problems on their own and the 2 way had problems puting even another 2 way after it. I didn't have time to keep experimenting so I used the 3 way even though I ended with one less connection than desired.

The amplied switch is from RS (15-2100). I have a couple non amplified switches I was using long ago before the connection outside started to go bad and that I used again after the RS switch proved to be insuffitient help later as the problem got worse and I added the amplifier at the entry point. During the change to digital, I had one those where the 15-2100 is and it didn't work decently. The 15-2100 is better as things stand now. I think my best bet is a second stage 2 way split followed by the amplifier I used to use at the entry, so the digital still splits out before the amplifier and any switch or split will probably work after it. I just don't have time to do all the testing and cable swapping in inaccessable places. While I had that amplifier in the system I had a bunch of problems, that I think were ringing, that depended on which short cables I used where throughout the system. I could handle any amount of switches and splitters but after each change I usually had to swap around short cables several different ways to find the combination that didn't ring.

I had previously tried removing each VCR and probably every individual cable and many combinations and never saw any one item that significantly messed things up (other than the 15-2100, which clearly helps the low analog channels while hurting the high ones).

Rob never commented on the A/V split part of the question. The back of the cable box is so hard to get to because of some built in furniture and short cables, that I'd like to get that right on first try.

I understand the issues with unterminated Ethernet and would expect similar here and at the moment have nothing unterminated other than possibly inside the 15-2100. But in the past I had found that those other switches leave the unselected inputs unterminated and when I first switched away from using those I experimented with getting them and all other unterminated ends out. It didn't noticably help.
Back to top
View user's profile Send private message Send e-mail Visit poster's website
johnsfine
Site Admin


Joined: 10 Aug 2003
Posts: 4767
Location: Bedford, MA

PostPosted: Wed Oct 08, 2003 7:40 pm    Post subject: Reply with quote

jamesgammel wrote:
Since you mentioned "cheap Y's" and A/V signals I assume you mean the regular yellow/red/white. For lowest loss, go with the heavier coax type shielded cables. Most times these are made with RG-59 coax cable. They are better than the skinny "cheap microphone"type cable in some really cheap "Y's".


Does that really matter in a two inch long Y? (I have good cable to use after the Y on both sides) Does it really matter with a strong clean A/V signal directly from the back of a cable tuner?

jamesgammel wrote:
You're better to amplify a cleaner, stronger signal than a weaker one that's picked up noise. Thus, The closer to the "source", the better and cleaner the amplification will work. In other words, you're better off to amplify a signal at the begionning of a run where the signal is stronger and cleaner than try to salvage a weak signal that's has noise introduced before it got there.


I understood that already and I wish I had that choice. The amplifier that I'm not using right now and intend to try again, previously was an enourmous help in a situation that I now understand was just a few feet past the bad connector, where there was a weak signal and very little noise. A few long cables, splitters and switches past there (where I first tried the 15-2100) there is plenty of noise added to the weak signal and an amp can't perform well.

I know I can't have the amp before splitting off the cable modem and I'm pretty sure I can't have the amp before splitting off the digital cable. Given the existing cable runs and location of equipment, those two splitting constraints make it very hard to put the amp before the long cable run.

jamesgammel wrote:
Outside, if you have splitters/amplifiers, etc. use the "weather-proof" connectors (they have an O-ring at the base), and use a dielectric grease on the fittings. (found at most automotive stores). This will help with the weather sealing, and cut down on corrosion which will degrade signals over time. It doesn't hurt to use the dielectric grease indoors either.


I don't have the skill to cut and replace that outside connector again. The new one has no O-ring and doesn't look weather-proof, but it's not in an easy location and I did a rotten job crimping coax in easier situations years ago. I never heard of dielectric grease. I saw that no such thing was used. I guess I should look into that, so I won't need to fight the cable company to get that problem spot fixed again in a few years (he only replaced one side of the problem connection).
Back to top
View user's profile Send private message Send e-mail Visit poster's website
The Robman
Site Owner


Joined: 01 Aug 2003
Posts: 18131
Location: Chicago, IL

PostPosted: Wed Oct 08, 2003 8:09 pm    Post subject: Reply with quote

johnsfine wrote:
Rob never commented on the A/V split part of the question. The back of the cable box is so hard to get to because of some built in furniture and short cables, that I'd like to get that right on first try.


I missed it, was it this...

johnsfine wrote:
My to do list includes trying splitting the A/V output so the first VCR can get it too and could switch electrically between analog (coax) and digital (A/V) input. Also my quick attempts at tapping one more device (4'th VCR) into the analog side also failed. Before or after the powered switch one more split seems to wreck analog reception for several devices vs. the present perfect digital and perfect analog for all but a few high channels on some devices. I have yet to experiment with puting back the signal amplifier I used before getting digital cable (before realizing all our reception problems were due to that bad connector outside). That worked very well at the point the coax entered the house, cleaned most of the problems caused by the connector outside and let me split however I wanted beyond it. But I can't use it there with digital cable and haven't had time to try it further in.


I assume you're talking about splitting the red, white and yellow outputs from the digital cable box. I'm using a ton of these splitters in my setup. I have the A/V outs from both Replays split so I can send them to each of two video selectors, one that controls what's showing on the TV screen and the other controls what gets recorded on a VCR. (I also have two DVD players feeding these selectors).

Bottom line, as long as you're getting good reception on the cable box using whatever cable you currently have run, splitting the A/V outs should do any noticable harm to the picture.
_________________
Rob
www.hifi-remote.com
Please don't PM me with remote questions, post them in the forums so all the experts can help!
Back to top
View user's profile Send private message Visit poster's website
po_boy96



Joined: 06 Oct 2003
Posts: 6
Location: south

PostPosted: Wed Oct 08, 2003 9:20 pm    Post subject: Reply with quote

The posts on this topic are very long so if I reply on something that has already been covered then just blame it on ADD Very Happy . Signal amps and cable modems are a bad mix, especially RS ones. If your cable company put the cable modem on the first split then they did it for a reason. Some systems can handle the modem being on a 4-way splitters where others need to be on the first split with a 2-way. From my experience most commercially available amps are not return path compatable (they do not allow upload). The only one that I know that works with upload is Scientific Atlanta, and they go out after about a year or two. You want to use digital Gig splitters (with frequency ranges of 5-1000) because they tend to be higher quality and are the only ones that can properly handle digital signal. Don't let RS or anyone else try to sell you gold plated fittings on prefab cable or gold splitters because they do not work any better than standard fittings and do not justify the cost. Use RG-6 as much as possible, I am not aware of any that is manufactured that is not shielded and the standard is dual shild which is plenty, quad shield for home use is overkill. Anyway back to the amp subject. Amps work fine if the original signal from the line is just weak, no degraded. All signal is amplified, including the noise, and the amp sometimes can put some noise of its own which is common with cheaper amps. As for sealing the outside fittings, use plumbers teflon tape if you cannot find dielectric seal. F-seal is used by the cable companies and all it is is teflon grease (very messy). In a pinch the teflon tape works great. Just make sure the fitting is tight. If the outside equipment is not mounted in a box then make sure all of the ground block and splitters are horizontal to the ground (the cable runs parallel to the ground.) Make sure the cable slopes down at a slight angle, this keeps water migration from working its way to the fitting. I probably just rambled on and missed your real questions so if you have any questions pertaining to cable, just let me know and I will try to help as much as possible. One more thing, make sure the stinger on your fitting (the copper center condutor) does not go past about 1/8 in. past the end of your fitting. Longer stingers that that can actually go onto the circut board in the splitter and cause major signal leakage and noise. Hope this is helpful.
Back to top
View user's profile Send private message
jamesgammel
Exile Island Resident


Joined: 03 Aug 2003
Posts: 397
Location: Gillette, Wyoming

PostPosted: Wed Oct 08, 2003 10:38 pm    Post subject: Reply with quote

John--

Better than "Y" cables would be a 2>1 adapter. I don't know how much room you have between the three rca phono jacks on the cable box, so you'd have to judge how these would work. RS cat# 274-881 (from a 2002 catalog, but I think they still carry them and the cat# should be the same.) Your two regular "vcr" (A/V) cables would plug right into them.

Dielectric grease is used in cars to keep and insulate spark jump in spark plug boots, and is also used on bulb contacts to prevent corrosion and maintain good electrical contact. I've had great results with "Permatex" "Dielectric tune-up grease" 67V. A little tube goes a long way and lasts for years.

Jim
Back to top
View user's profile Send private message Send e-mail Yahoo Messenger
mr_d_p_gumby
Expert


Joined: 03 Aug 2003
Posts: 1370
Location: Newbury Park, CA

PostPosted: Thu Oct 09, 2003 1:34 pm    Post subject: Reply with quote

OK, I'll throw my two cents in here too...

My setup is somewhat similar to yours. Cable enters house, goes through a special two-way (meaning both upload and download, or bi-directional) splitter, one side of which is the cable modem. The other goes up one story to my main AV setup, where it goes through another two-way (bi-directional) splitter. One side goes to the digital cable box (which has an IP address and needs to talk to the cable company's servers), the other goes to a wideband (non-Radio-Shack) amplifier that feeds multiple normal splitters to feed a ReplayTV, 2 VCRs, a TV, and three feeds to other parts of the house.

Before I got the digital cable box, everything except the cable modem was going through the amplifier, and most devices had a good signal. The feeds to other parts of the house are 70's vintage, and have significant high frequency loss, so upper channels were somewhat marginal in those locations. The amplifier helped (but did not cure) this situation, though the next time the plaster is ripped off all my walls I'll replace the cable... Rolling Eyes

When the digital box was installed, it had to be fed signal before the amplifier in order to allow two-way communications. Initially, the signal to the box was marginal, and 2/3 of the digitals channels suffered from dropout. The installers accused everything in my system of being responsible for the problem, but replacing RF cables & splitters in various places sort of got it working at the time.

Recently, the cable company was in the neighborhood replacing all the exterior cabling. Before they arrived at my house, I noted the signal levels displayed on the digital cable box (by tuning to the channel for this purpose). After they replaced all my old outside cable from the street to my house, the digital box showed a drop of -6dB in signal strength! After several days of complaining and calling the cable company, they investigated the matter. What cured the problem and gave me back my missing 6dB was this: replacing the brand new connector on the end of the cable on the street, and connecting it to a different tap on the distribution box. So, I believe your story about the bad connectors.

One side effect of using the amplifier to cram signal down the crappy RG-58 inside the walls is that it's poor shielding allowed the signal to be re-radiated. This had the effect of drastically reducing the range of my garage door opener remotes. I solved this by disabling the opener's internal receiver and locating an external receiver right above the garage door, and retuning everything so that it operated between cable channels.
jon_armstrong wrote:

Every RF amplifier, switch, or splitter that I have ever purchased from RS seemed to degrade the higher frequency signals (more than other brands) but that is from the past since I never buy RF transmission stuff there anymore. But you can always try it and return it. (I don't think you want any amplifier between the feed and the cable modem.)
...
PS. I hadn't seen Rob's post since I got interrupted while posting this so I did not intend to refute Rob's more recent experience with RS gear Smile
I'm with you on the RS amplifiers. I have a whole box of them stored away. The only thing they have ever proven useful for was to boost the channel 3 output of a VCR or cable box.
johnsfine wrote:
Does that really matter in a two inch long Y? (I have good cable to use after the Y on both sides) Does it really matter with a strong clean A/V signal directly from the back of a cable tuner?
Obviously the cable is not an issue here as long as it's not defective. And the gold plated stuff does no good whatsoever if you plug it into an ordinary nickel-plated jack. About the only thing to consider is that the video inputs of each device are typically loaded with 75 ohm termination resistors, and the video outputs of most devices have some series resistance (up to 75 ohms or more). So when you conect one output to multiple inputs, you tend to reduce the signal level overall to all devices. Some will be better at working with lower amplitude video levels than others, though technically they don't have to work at all according to specs.

The cheap RS amplifiers usually are nothing more than an emitter-follower buffering the output, feeding each device through it's own series resistor. Crude, but it should be effective as long as it does not introduce noise in the signal. (BTW, the audio in the RS amps is not amplified at all--the jacks are just wired in parallel.)

One other crude but effective thing you could try is to remove the 50 ohm resistors from the video inputs of all but one device. Might not work in all cases, especially if you have long cable runs, but it should prevent the video signal amplitude problem.

Edit: My bad... corrected reference to 50 ohm resistors to 75 ohm.
_________________
Mike England
Back to top
View user's profile Send private message
po_boy96



Joined: 06 Oct 2003
Posts: 6
Location: south

PostPosted: Sat Oct 11, 2003 1:02 pm    Post subject: Reply with quote

One quick thing about using dielectric grease on your outdoor fittings, make sure you do not get it on the copper center conductor. Even a small ammount will cause you a great deal of headaches.
Back to top
View user's profile Send private message
johnsfine
Site Admin


Joined: 10 Aug 2003
Posts: 4767
Location: Bedford, MA

PostPosted: Mon Dec 15, 2003 1:54 pm    Post subject: Reply with quote

I just figured I'd update this, now that the changes have been working well for a while. All the reception problems are fixed and I have more flexibility on which VCR gets which signal.

The present wiring is:

1) Cable enters and goes through a 1000Mhz splitter, one side of which is the cable modem, the other side continues to (2). (All the other splitters are 500Mhz).

2) Long cable through walls with a couple splices (unavoidable without ripping out walls again) then a 2 way split, one side of which is input to digital cable box, other side is (3).

3) A 500Mhz signal amplifier (the primary improvement vs. the previous wiring). Then a 2 way split, one side of which is the coax input to VCR-A. The other side of which is (4C).

4) A 5 input (only 4 used) 3 output amplifying manual switch (used most of the time as a a 3 way splitter because I rarely switch any of the outputs away from the C input. The 4 inputs are:
4A) The coax output of VCR-A
4B) The coax output of VCR-B
4C) The raw cable signal (from 3 above).
4D) The coax output of the cable tuner (from 5 below).
The three outputs are:
4X) The primary coax input of the big TV
4Y) The coax input of VCR-B
4Z) The cable to items in another room (see 8 below)

5) The coax output of the cable tuner goes through a 2 way splitter. One side is switch input 4D (above). The other side is the secondary coax input to the big TV (This secondary coax input is the only one of the TV's five inputs that can't be viewed in the PIP, so we sometimes need to use either a VCR or the manual switch 4X to route that signal to the PIP. More often we skip the cable tuner entirely and use the TV's tuner, which gets most of the stations we ever watch).

6) The A/V output of the cable tuner uses cheap A/V Y-connectors and cheap audio cable to connect to the A/V inputs of VCR-A and VCR-B (Despite the cheap wiring, the signal is perfect). Each VCR can switch electronically between A/V input from the cable tuner and coax input from the raw cable.

7) The A/V outputs of VCR-A and VCR-B go to the two back A/V inputs of the big TV. The front A/V input of the TV is manually plug/unplugged among the four different gaming systems my wife (over my strong objections each time) let my sons buy, and sometimes the camcoder.

8 (from 4Z) A cable goes upstairs to 8A, an input to a 4 input (only three used) 2 output unpowered switch, which is normally used as a 2 way splitter because we rarely switch away from this input. Other inputs:
8B) A second cable (non digital) from the outside, left over from when we had the non digital cable service, whose channels were split between two physical cables. Most of its channels duplicate the other cable now. It has two channels that aren't in the digital lineup. Neither has any show we would ever watch, but I check it on rare occasions.
8C) Coax output from VCR-C
Outputs:
8X) Coax input of VCR-C
8Y) Coax input of VCR-D

9) VCR-C has coax input and output to switch 8, plus A/V input from VCR-D and A/V output to the second TV.

10) VCR-D has coax input from switch 8, coax output to the second TV, A/V output to VCR-C, and NOTHING connected to its A/V input (I'm really slipping. I left something unconnected).
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic       JP1 Remotes Forum Index -> JP1 - General Forum All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


 

Powered by phpBB © 2001, 2005 phpBB Group
Get Smart! the band's official homepage Rockabilly Central