How do I test cable for 75 ohms? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 5 Old 03-06-2000, 02:43 PM - Thread Starter
AVS Special Member
 
TimHuey's Avatar
 
Join Date: Jun 1999
Location: Fort Lauderdale, FL USA
Posts: 1,890
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked: 12
I am getting ready to hook up some component cables from my DVD player to my new TV and I want to make sure the cables are 75 ohms. I have an ohm meter. It can't be as easy as connecting the leads to each end of the cable and looking at the meter (nothing is ever that easy), so is there a way to do it?

Tim

HTPC. Onkyo 636, Polk audio speakers and Klipsch sub. KHO-7 Outdoor speakers. Homeseer homecontrol over Z-wave.
TimHuey is offline  
Sponsored Links
Advertisement
 
post #2 of 5 Old 03-07-2000, 12:21 AM
Advanced Member
 
Dave928's Avatar
 
Join Date: Jun 1999
Location: Seattle - it's not Hell, but you can see it from here!
Posts: 804
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12

not really. the way it was explained to me is that the impeadance rating of the cable is measured with 1000 feet of cable with a 1KHz test load on the cable. so you could have a 50 Ohm RG-58 cable or a 75 Ohm RG-59 cable, you won't see/hear a difference with only a meter or two of cable.

even if that's not entirely correct, you still can't measure it with an ohmmeter...

that's just my opinion, i could be wrong...



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

dave

Widescreen DVD - Because a superior format requires superior formatting.

No, i can't go out, i'm watching Garbo...

Dave928 is offline  
post #3 of 5 Old 03-07-2000, 05:59 AM
Senior Member
 
Dennis Nicholls's Avatar
 
Join Date: Jan 2000
Location: Boise, ID
Posts: 421
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Tim,
The easy way to see if your cable is 75 ohms is to look up the part number of the cable, which should be stamped on the jacket. The way you test if the cable is 75 ohms is to terminate the far end with a 75 ohm resistor, and send a signal down and look for reflections. There are boxes that do this but I think they are expensive. They are called "time delay reflectometers" IIRC. Your ohmmeter is useless for this purpose.

Feline videophiles Condoleezza and Dukie
Dennis Nicholls is offline  
post #4 of 5 Old 03-07-2000, 06:10 AM - Thread Starter
AVS Special Member
 
TimHuey's Avatar
 
Join Date: Jun 1999
Location: Fort Lauderdale, FL USA
Posts: 1,890
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked: 12
As both of you have stated, I have discovered that I can't do this with my ohm meter. I should have figured this out before I tried. I felt pretty stupid when I selected ohms on the meter then connected one lead to one end of the wire and one lead to the other end of the wire and looked at the meter. I just let out a small "DUH" when the meter pegged out at 0 resistance.

Tim

HTPC. Onkyo 636, Polk audio speakers and Klipsch sub. KHO-7 Outdoor speakers. Homeseer homecontrol over Z-wave.
TimHuey is offline  
post #5 of 5 Old 03-07-2000, 04:35 PM
AVS Special Member
 
David Richardson's Avatar
 
Join Date: Sep 1999
Location: Birmingham, Alabama
Posts: 2,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
From what I understand depending on what freq. you insert into the cable your impedence will change. So being thats about all I can actually write about I will stick with a cable that also has the bandwidth capability of holding a constant impedence in the band of HDTV or current need. There is a difference in cables. But to spend $1000 on a DVD compoent cable connected to a cheap DVD player or a entry level TV is not recommended. Not implying anything, just use best judgement.IMHO.

Dave

David Richardson is offline  
Closed Thread General Home Theater & Media/Game Rooms

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off