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| Thread ID: 78630 | 2007-04-23 01:03:00 | COAX and MulitMeters for Testing | pctek (84) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 543341 | 2007-04-23 01:03:00 | So, anyone an expert on coax and/or testing cable with multimeters? Husband checked, no reading, shorted it and got 0.34 or some such. His conclusion is cable is OK. This is RG6 cable. |
pctek (84) | ||
| 543342 | 2007-04-23 01:21:00 | All that a multimeter will reveal is whether the cable is open circuit, it will not tell you whether the cable is ok or not. This is because a coaxial cable is a transmission line which has properties other than resistance, such as characteristic impedance, capacitance and inductance. Then it has attenuation loss, and this can change or increase due to water in the cable, or mechanical damage. So it requires more equipment than a multimeter to check whether the cable is ok or not. www.sencore.com www.radio-electronics.com |
Terry Porritt (14) | ||
| 543343 | 2007-04-23 06:11:00 | It depends on why you are testing. A multimeter is fine if you are just checking for continuity, and a visual will tell you if it is full of water. Terry's stuff is way too complicated for a simple "is my coax cable faulty" test. What is the history? If you had a sudden failure, go outside and see if the antenna is still there. Laugh if you will, but in years gone by I was more than once called to a TV fault that turned out to be a collapsed antenna. Which reminds me of the woman who expected me to fix her TV in the laundry. I told her she didn't watch it in there for a reason, and for the same reason (I was in a charitable mood) I didn't fix them in laundries either. Made her carry it back to the lounge for me too, I wasn't feeling that charitable! Cheers Billy 8-{) P.S. Went to a few houses where I'd have preferred to fix it in the laundry too. Squelchy carpet and a pee-line around the walls put me off every time. :yuck: |
Billy T (70) | ||
| 543344 | 2007-04-23 08:08:00 | and a visual will tell you if it is full of water. the cooper wire tends to go black and the foil breaks up very easly. also look for any werid bulges or flat spots in the cable. |
tweak'e (69) | ||
| 543345 | 2007-04-24 04:23:00 | TV cable lives in the horrible wet world. It can rot away. If it has foam insulation ("low loss") it absorbs water and becomes lossy. :( An "open" reading would be fine, but that's a low voltage measurement. It could still be very lossy. The .34 (presumably ohms, not kilohms or megohms) would mean that it's still conducting. So it's not totally useless. But you have a good sophisticated test instrument. Do you get a good picture on the TV set? |
Graham L (2) | ||
| 543346 | 2007-04-24 05:11:00 | If you don't really care about the results, any old test gear will do. Multimeters and thermometers will tell you a bit, but GrahamL's test is really the best. | R2x1 (4628) | ||
| 543347 | 2007-04-24 05:13:00 | Not a TV aerial. This was for a broadband connection. Anyway the verdict is it was the receiver faulty. |
pctek (84) | ||
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