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The following page was printed from RemoteCentral.com:
| Topic: | Measuring video cables This thread has 40 replies. Displaying posts 16 through 30. |
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| Post 16 made on Sunday October 1, 2006 at 01:09 |
QQQ Super Member |
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Posts: | January 2002
4,806 |
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| Post 17 made on Sunday October 1, 2006 at 01:12 |
QQQ Super Member |
Joined:
Posts: | January 2002
4,806 |
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Deleted due to edits by Ernie. No need to comment.
Last edited by QQQ
on October 1, 2006 01:52.
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| Post 18 made on Sunday October 1, 2006 at 01:47 |
Ernie Bornn-Gilman Yes, That Ernie! |
Joined:
Posts: | December 2001
30,104 |
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On October 1, 2006 at 00:57, Audible Solutions said...
Mind clearing up what "I will bet that one hundred feet
of 18 gauge SPEAKER WIRE" is supposed to mean? Belen
1694A is most assuredly a "low loss coaxial cable," Sure! Note that the brand is Belden, not Belen, and I did not end my sentence with the idea "speaker wire," but went on to make a comparison between speaker wire and your claim that the Belden would have 72 dB loss at 10 mHz: On October 1, 2006 at 00:44, Ernie Bornn-Gilman said...
I will bet that one hundred feet of 18 gauge SPEAKER WIRE
won't be down 72 dB at 100 feet at 10 mHz. Are you sure
you read or copied this correctly? I even capitalized the term so you would get that I was implying (pretty clearly, I thought) that you were saying that commonly used GOOD Belden 1694A performed worse at 10 mHz than 18 gauge SPEAKER WIRE. And indeed, Late Night Bill pointed out that you misread the spec for the Belden, and that it is .72 dB per hundred feet. I think that makes it better than the Mogami, but I'm not going to go back and read that post again to make sure. It is at least close, and not more than, say SIXTY dB different over a 100 foot run.
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A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw |
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| Post 19 made on Sunday October 1, 2006 at 10:12 |
simoneales Select Member |
Joined:
Posts: | May 2005
1,782 |
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I spent the day today giving Harley rides to children with terminal illnesses. I managed to make it through the day without cracking up. When I read all the above....i go cross-eyed and want to cry....go figure!
Simon.
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I guarantee I'll tell you the truth and I guarantee I'll tell you what you need to know but I can't guarantee that I'll be telling you anything you want to hear. |
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| Post 20 made on Sunday October 1, 2006 at 13:36 |
shlampen Lurking Member |
Joined:
Posts: | October 2006
5 |
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On October 1, 2006 at 00:10, Audible Solutions said...
[Link: mogami-wire.co.jp]pps 40-41, Please note the specification of .018 db/ft @10MHz and the 18.3Pf/ft capacitance specifications for the high frequancy 75 ohm coaxial cable. That works out to 1.8db for 100 ft @ 10MHz and 1830Pf @ 100 ft Let's look at the Beldon 1694 as it specs out the best of the Belden cables. It's capacitance spec is 16.2Pf/ft and loss @ 10MHz .s .72 At 100 ft of cable that's 72 db and 1620Pf Assuming the specifications are accurate, damned right the Mogami will perform better than the Beldon 1694A. Alan
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Steve Lampen
Multimedia Technology Manager
Belden |
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| Post 21 made on Sunday October 1, 2006 at 13:42 |
shlampen Lurking Member |
Joined:
Posts: | October 2006
5 |
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On October 1, 2006 at 00:10, Audible Solutions said...
[Link: mogami-wire.co.jp]pps 40-41, Please note the specification of .018 db/ft @10MHz and the 18.3Pf/ft capacitance specifications for the high frequancy 75 ohm coaxial cable. That works out to 1.8db for 100 ft @ 10MHz and 1830Pf @ 100 ft Let's look at the Beldon 1694 as it specs out the best of the Belden cables. It's capacitance spec is 16.2Pf/ft and loss @ 10MHz .s .72 At 100 ft of cable that's 72 db and 1620Pf Assuming the specifications are accurate, damned right the Mogami will perform better than the Beldon 1694A. Dear Wire & Cable Friends, I was encouraged to join your mighty group by David Haddad, one of your inmates. The post above is in error (as all of you seemed to know!). The loss on 1694A at 10 MHz is 0.72 dB per 100 ft. That's a whole lot better than 1.8 dB (assuming that's correct. I haven't looked at the Mogami site.) Somehow, that 0.72 dB was assumed to be the loss per foot, which is incorrect. Regarding IRE's. That is level but, as has been pointed out, it is frequency based. I would be very interested to know what (if any) Belden cable is 8 IRE down at any frequency compared to any other cable. I will keep lurking!
Alan
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Steve Lampen
Multimedia Technology Manager
Belden |
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| Post 22 made on Sunday October 1, 2006 at 13:49 |
shlampen Lurking Member |
Joined:
Posts: | October 2006
5 |
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Friends-
I was encouraged to join your esteemed group by David Haddad, so here I am. As you all seem to have figured out, the loss on Belden 1694A is .72 dB per hundred feet (not per foot) and that is significantly better than 1.8 dB. (Didn't go to the Mogami website, so I am assuming that number is correct.)
If you have further questions on Belden products, or wire and cable in general, I would be delighted to help.
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Steve Lampen
Multimedia Technology Manager
Belden |
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| Post 23 made on Sunday October 1, 2006 at 14:13 |
David Haddad Long Time Member |
Joined:
Posts: | September 2005
244 |
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On October 1, 2006 at 13:42, shlampen said...
Dear Wire & Cable Friends,
I was encouraged to join your mighty group by David Haddad,
one of your inmates. I will keep lurking! Hello Folks, I am also a lurker here, and since Stephen has often assisted me with technical issues pertaining to cables, when I read this thread I thought would E-mail him and ask him to comment. For those that don't know who Stephen is, he is one of the lead engineers at Belden and has also written some excellent books on cabling.
Last edited by David Haddad
on October 1, 2006 18:34.
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| Post 24 made on Sunday October 1, 2006 at 17:47 |
Late Night Bill Long Time Member |
Joined:
Posts: | February 2004
495 |
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Welcome Steven and David to RC, the most unlikely place and best place to talk to actual working people in the industry. So as promised I have moved my spreadsheet work onto a page. I can add some more cables if you request a particular make and model. [Link: neoprointegrator.com]-Bill
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| Post 25 made on Sunday October 1, 2006 at 19:07 |
cjoneill Select Member |
Joined:
Posts: | December 2002
2,174 |
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Thanks Bill, that's a nice explanation and comparison. FYI, the Canare L5CFB would be their cable that is comparable to the Belden 1694a.
CJ
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I'm not a pro |
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| Post 26 made on Sunday October 1, 2006 at 19:14 |
Brentm Ethereal Home Theater |
Joined:
Posts: | July 2003
2,688 |
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I am thrilled to see Mr. Lampen has now joined our fraek show.
I have talked with Steve several times at past shows and find him to be both entertaining and articulate.
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Brent McCall
Paid Endorser for;
Ethereal (386) 846-7264 Cell |
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| Post 27 made on Monday October 2, 2006 at 00:53 |
Ernie Bornn-Gilman Yes, That Ernie! |
Joined:
Posts: | December 2001
30,104 |
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Steve,
you and I had a conversation maybe ten years ago, which I have paraphrased here a few times, in which I concluded that the only reason in most installations to use RG-6 quad instead of just foil & braid RG-6 was so the next installer couldn't come in, shake his head at the cable, and steal the client by saying, "I see they didn't choose to use the good stuff." And you pretty much agreed.
I use the pocket version of your book on wire installation, and really appreciate the information in it. And I truly welcome you to the site. As I think you said in another post, you have lurked here for a while, which is good, because we won't be strangers to you.
Welcome!
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A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw |
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| Post 28 made on Monday October 2, 2006 at 11:05 |
Thon Founding Member |
Joined:
Posts: | November 2001
726 |
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On October 1, 2006 at 00:44, Ernie Bornn-Gilman said...
Alan, some of the things you say don't pass the stink
test. And I mean the one where you don't even have to
lift your arm:
Copy and paste, I swear. Go back and read it. This guy
said that if a client DOES pay for a test, you SHOULD
NOT do it? That is what you said, right?
I will bet that one hundred feet of 18 gauge SPEAKER WIRE
won't be down 72 dB at 100 feet at 10 mHz. Are you sure
you read or copied this correctly? 72 dB is a damn effective
spec for a rejection filter! And if we figure a probably
excessively BAD response curve for the wire of, say, -
6 dB per octave, which is a first-order filter, not a
hunk of cable, then this wire would be down, let's see
66 dB at 5 mHz, 60 dB at 2.5 mHz, 54 dB at 1.25 mHz, let's
say 52 dB at 1 mHz, 46 dB at 500 kHz, 40 dB at 250 kHz,
36 dB at 125 kHz, 30 dB at 62.5 kHz, 24 dB at 31.25 kHz,
18 dB at 15.625 mHz, 12 dB at 7.8125 mHz, 6 dB at 3.9
mHz, 0 dB at 1.95 mHz
In other words, if this wire were so crappily made that
it performed as a first-order filter, we could expect
it to be flat to just under 2 mHz. Now, if its high frequency
attenuation were any less than 6 dB per octave, we would
soon have it performing with noticeable losses in the
audio spectrum. I don't think this passes the stink test.
No, this spec does not pass the stink test. Once again, Alan, you are baffled by the facts.
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How hard can this be? |
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| Post 29 made on Monday October 2, 2006 at 11:10 |
Thon Founding Member |
Joined:
Posts: | November 2001
726 |
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work without compensation is foolish. He did not say
that is should not be performed if the client was paying
for it. I mistyped and should have included a "not" between
"are" and "paid." Big difference. This is why I give you a hard time about spelling and grammar. Our business is all about communication. I expect that the regular posters to this website are the best of the best and I count on everyone here, even you, Alan, to present this image and differentiate us from the slammers.
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How hard can this be? |
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| Post 30 made on Monday October 2, 2006 at 17:09 |
Ernie Bornn-Gilman Yes, That Ernie! |
Joined:
Posts: | December 2001
30,104 |
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On October 2, 2006 at 11:10, Thon said...
Big difference. This is why I give you a hard time about
spelling and grammar. Our business is all about communication.
I expect that the regular posters to this website are
the best of the best and I count on everyone here, even
you, Alan, to present this image and differentiate us
from the slammers. This is indeed a big difference. It is not enough to say it was a mistake. I don't want blood, but you have to realize that by not typing it correctly, and not reading it through before posting (or even after, which is where I usually find my typos), you didn't just NOT do something positive. Instead, you actively did something negative, and it takes work to come back from that position and just be at zero where maybe you can say something that adds to the discussions -- and be taken at face value. This thread would be shorter and clearer if you had either not posted at all, or if you had used that "not." If you had added that the Belden spec was "per 100 feet," the entire reason for that post would have evaporated! Apparently it's not just your own writing that you read too rapidly, eh? Heck, who knows what pearl of wisdom you are now mistyping, and thus misrepresenting. Someone's signature says something like "be careful when reading health books: you might die of a typo." Well, a health book with a typo is worse than no health book at all. Don't let your posts be worse than no post at all.
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A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw |
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