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Discussion Starter · #1 ·
I am currently typing this message using a 25ft shielded cat 5 Ethernet cable. The image is extremely clear noticeably better than my 30 foot bundled coax that I normally use. To make the test more difficult, the Cat 5 cable is actually two separate pieces with a junction box 6 feet away from my monitor. This will be the cable that I will use as my HT redesign reaches final completion.


The idea actually came from Thumper. Dismayed by the price of plenum or standard rated coax cable and video amplifiers for his installed, he started tinkering with the idea of using Ethernet cable to run his video signals. He shared his success with me


He told me that I could get good results with standard Cat 5E cable and outstanding results with shielded Cat 5.


Well, premade shielded Cat 5 cables are a little hard to come by so I first tried the experiment using unshielded cat 5. I bought a 25 footer cut it into two 6 foot and 19 foot section and put an HD-15 on each of the cut ends. I then put an in-line Ethernet splicer to join the two Ethernet ends (explain latter). This yielded a long HD-15 to HD-15 cable.


Well the results with this cable where far from stunning. I got plenty of ringing and blurring at most frequencies including really bad results at 60 Hz.


I explained my results to Thumper and he told me to redo it with shielded Cat 5. I was very skeptical because I wasn't having a noise problem but ringing (i.e. impedance mismatch) problem instead.


That's when it hit me; general Cat 5 is 100 ohm twisted pair; however, with the shield tied to ground on the shielded version this would help lower the impedance to closer to video's 75 ohm requirement. I decided to give it another try.


The construction details:


The only local place I could find shielded Cat 5 products was at Fry's. L-com has them but they are mail order and a little more expensive.


I did the exact same thing as before. I bought a 25 foot shielded cat 5 cable and cut it into a 6 foot and 19 foot piece. I also bought a shielded Cat 5 junction box, two HD-15 male solder cup plugs and to 9-pin metal hoods (HD-15 is the same size). I wired the HD-15's in the following fashion to the shielded cat 5 cable.


HD-15 pin Cat 5 color

-------------------------

1. Red + Orange

2. Green + Green

3. Blue + Blue

4.

5.

6. Red - (aka GND) Orange stripe

7. Green - (GND) Green stripe

8. Blue - (GND) Blue stripe

9.

10. Ground (GND) shield wire.

11.

12.

13. H sync Brown

14. V sync Brown stripe

15.


The "-" signals are actually the very same ground as "Ground" is. The H and V don't need their own separate ground line. The results were excellent as I stated before.


At this point you might be saying cool but what does shielded Cat 5 give me over bundled coax? It gives a few things:


1. Thinner form factor.

2. Cheaper cable. Plenum being much cheaper

3. Much easier to solder to an HD-15 connector. Bundled coax requires shield terminators when soldering and big mouth back shells to allow the larger diameter of the cable to exit.

4. similarly, no break-out BNC to HD-15 cables required. These bring their own problems


and my favorite,


5. It allows me to manually switch four RGB sources between 2 displays. This would normally require a matrix switcher which is usually $1000+. To do this, I have two Ethernet jacks (one for my UP-1100 and one for my Princeton Graphics monitor) and four cables (HTPC, AccessDTV, Digital cable and Dreamcast) that go in in any configuration that I want.


All of this with an outstanding video quality to boot. This is really cool.


Thanks Thumper,


-Mr. Wigggles


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The Mothership is now boarding.


[This message has been edited by MrWigggles (edited 06-12-2001).]
 

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makes you wonder what you could do with a simple hub

 

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Mr. Wiggles,

You may be an excellent engineer, but you are not a marketing executive. What the videophile community wants is a cable that "increases the realism and color saturation, rendering an image that exceeds the original source, causing the viewer to be immersed in a three dimensional pan-reality!"

Your cable would likely qualify if shrouded in a silver / mu metal braid, and charged $200 a meter.



SM
 

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Another AVS investigative reporting success. Way to go Mr. Wigggles!!! I have been waiting for a matrix switcher for a reasonable price. I was passively interested until I read that part. What do you suppose will be the effect as the cables are lengthened?

Quote:
originally posted by raoul:

makes you wonder what you could do with a simple hub

Actually it makes me wonder what he could do with a string and a used yogurt cup
However, a hub sounds like a bad idea since all of the devices could be feeding at the same time. I'll have to investigate the junction box Mr. M mentions as I'm unfamiliar with it.



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[This message has been edited by Man E (edited 06-13-2001).]
 

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Mr. Wiggles,


I hope I am not asking too much, but would you be so kind as to post a picture or two? I think that would help me understand exactly what you did (so i can do it too!)


Specifically,


"I also bought a shielded Cat 5 junction box, two HD-15 male solder cup plugs and to 9-pin metal hoods (HD-15 is the same size). I wired the HD-15's in the following fashion to the shielded cat 5 cable."



Thanks,


Eric


[This message has been edited by eric_steimel (edited 06-13-2001).]
 

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Discussion Starter · #7 ·
I will post pictures when I get a chance after Infocomm.


-Mr. Wigggles


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How about something like this:

Blackbox RJ45 spliter


(BB doesn't seem to like the link, you can go to blackbox.com and look under Cables & Connectors -> Adapters -> RJ-45 Modular Splitters)


Might let you view the same source on more then one TV.


-apnar


[This message has been edited by apnar (edited 06-13-2001).]
 

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Quote:
Originally posted by apnar:
How about something like this:

Blackbox RJ45 spliter


(BB doesn't seem to like the link, you can go to blackbox.com and look under Cables & Connectors -> Adapters -> RJ-45 Modular Splitters)


Might let you view the same source on more then one TV.


-apnar


[This message has been edited by apnar (edited 06-13-2001).]

Looks like the FM810 or FM830 models would do it, they're shielded and they send all pairs to each jack. Just don't get the 'b' pinning models... Now, if they only had one of these with a switch built in...

STP isn't cheap by Ethernet standards, but it sure as heck is cheaper than braided coax, and much easier to run, crimp, and maintain. I LOVE this idea!!!

 

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Pinning A only passes two lines. Pinning B passes all lines. I can't see how this would be safe because if all devices were active at once, there would seem to be an overload condition... but I'm no expert.


Mr. Wigggles, in the absence of your pictures could you please post make/model information or make some comment on this issue?


Thanks!



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MrWiggles, I want to see those photos, yes I know I have to wait until Monday. One question, why do you buy a cable and then you cut it in two pieces...sorry for the question but I don't know anything about ethernet cables.

Federico
 

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Mr. Wiggles,


Interesting post. Could you please provide the cable brand name and manuf. p/n for the 25 ft. shielded Cat 5 that you purchased from Fry's? Also, do you know if all "plenum" rated cable indicated shielded? Fry's carries a 500 ft spool of that.


Thanks!


Jim
 

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Mr. Wiggles,


Interesting post. Could you please provide the cable brand name and manuf. p/n for the 25 ft. shielded Cat 5 that you purchased from Fry's? Also, do you know if all "plenum" rated cable indicated shielded? Fry's carries a 500 ft spool of that.


Thanks!


Jim
 

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Hi MrWigggles,


After a quick Fry's run last night, I sat down and built a Cat-5 VGA cable, per your instructions, using shielded Cat5 cable and a shielded coupler. Overall, the image quality was very nice, certainly much better than the replacement VGA cable I mistakenly bought last week. (ghosting like you wouldn't believe)


However, I did notice a small amount of noise in the image, when compared to the 3' cable I usually run between my HTPC and my DLP projector. Did you do any A/B tests using a standard cable and notice any differences? (I don't think I would have noticed any difference if I was using a tube based display)


Also, did you jumper the shield wire to the metal frame of the connectors? (haven't tried this yet) The shielded cable I picked up (the only one I could find on the shelf
) was only rated for 100mhz, as opposed to the 350mhz cable I usually use, not that this should make a huge difference here, but thought I'd ask anyway.


This was more of an experiment for me at the moment, as my HTPC and projector are right next to each other. But a cable of this type will be very useful when I add an HDTV set-top box to the main equipment rack on the other side of the room in a few months. Now I've got to open up one of the wall jacks this week and see what kind of Cat5 the contractors put in last year.



Thanks.

DB.
 

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The difference between Cat 5, 5e and Cat 6 cables is almost totally in the realm of crosstalk rejection. This is done through twisting the different pairs at different ratios. as the cable gets longer this will start to be noticed. IE Pair 1, pair 2, pair 3 and pair 4 are all different lengths. At a longer distance this will manifest itself as a convergence error.


As far as the rating of 100 mhz goes, this is due to the rating of the category. the cable will handle higher frequencies, just with more loss. Cat 6 cables are all rated at 350 MHz. Twisted pair wiring has alot more loss than standard coax, so longer lengths should not be attempted in this manner. Also, it is very prone to picking up stray EMI and RFI. THere are companies that allow you to run over TP cabling distances of 1000' and sometimes longer with High resolution signals and not see any noticeable difference. THese however involve a transmitter and a receiver.
 

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Discussion Starter · #16 ·
Dizzman,


Thanks for the info but in the realm of HT I don't think we will have any convergence error under 50 Ft.


Like I stated earlier I did my experiement on a 25 Ft cable and I don't plan to use anything that long in my final install. Results at 25 ft were nearly flawless and would be considered great for any 25 ft cable.


Don't bother with the bandwidth numbers they are pretty much useless for comparison and are completely dependent on length. For instance, a 1 ft cable of any material would have an almost infinite bandwidth.


Please also bear in mind that HD is a 30 MHz signal, SXGA at 85Hz is about 60 MHz. I tried my cable at XGA at 85 Hz and that is higher than HD with no noticeable softening.


The pF per foot of shielded cat 5 are actually less than normal coax an that is what plays a significant role in frequency bandwidth.


-Mr. Wigggles


------------------

The Mothership is now boarding.


[This message has been edited by MrWigggles (edited 06-18-2001).]
 

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To help those trying this cabling application.


This is a followup to the termination configuration Mr.Wigggles layed out in his starter post above:


[To crank up the performance yet another notch, solder all the "grounds" and shield together (inside the shells) at both ends even though the video card & projector combine these grounds on their circuit boards.]


So far we have installed about 150 overhead monitor & projector connections this way and have 60 more on tap to do in the next two weeks. It really does work



Thumper
 

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Thumper, thanks for the input. What lengths are you achieving in these installs?

Thanks!



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The button is labeled "Play", not "Pay". STOP the MPAA!

Our Silent Angels

Please visit The Manny Page!
 

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Discussion Starter · #19 ·
Otaku,


If you use the cable with your DLP projector you might have to mess with the fine tuning phase adjustments. I got absolutely no noise using my cable. These type of adjustments are pretty typical when changing your cable typw and especially length.


I didn't ground the metal shield of the HD-15 to ground. It wasn't necessary and it would have taken a lot of heat to solder.


everyone,


I will get the pictures ASAP.


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any pics yet to further illustrate on how to build these. It would be difficult to solder a VGA HD-15 connector to all those cat5 cables wouldn't it? Can you provide a little more detail as to the cables construction Mr Wiggles?


My projector/DTC 100/HTPC only use VGA connections not component video cables. Are these cables suitable for my application then? These cables also have to be able to connect to an Extron VGA switcher as well.



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Serge

Parasound AVC 1800

B&K AV 5000 II

Monitor Audio Silver 5's, silver center and silver 3's(rears)

HSU VTF 2

Toshiba DVD

Mitsubishi LVP X70 FPTV

Dalite High Contrast Da-mat 16:9 grey screen

RCA DTC 100

HTPC consisting of Duron 750, AOpen motherboard, Radeon LE video and Turtle Beach Santa Cruz sound
 
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