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Identifying coax cable.
Have a 100 foot roll(approx) of used coax cable which has no markings
printed on it. Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? Going by the size it looks similar to 50 ohm but I'm not sure. Any suggestions would be appreciated. |
Identifying coax cable.
Boozo wrote: Have a 100 foot roll(approx) of used coax cable which has no markings printed on it. Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? Going by the size it looks similar to 50 ohm but I'm not sure. Any suggestions would be appreciated. You didn't mention what you have to make measurements with. The simplest way to make a quick estimate is probably to guess at the velocity factor first: solid polyethylene is about 0.66, and foam polyethylene is roughly 0.78. The impedance in ohms is 60*velocity factor*ln(D/d), where ln is the natural logarithm, and D/d is the ratio of inner to outer conductor diameters. So for solid polyethylene dielectric, D/d is about 3.5 for 50 ohm line, and about 6.2 for 72-75 ohm line. Even for fairly small line, it's not difficult to tell by just looking at it. It's also possible to measure the capacitance of the lenth of line and the electrical length in nanoseconds, and calculate the impedance from those two. If you can measure RF impedance, measure the line with the far end open, and with it shorted, and take the square root of the product of those two. Cheers, Tom |
Identifying coax cable.
Boozo ha escrito: Have a 100 foot roll(approx) of used coax cable which has no markings printed on it. Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? Going by the size it looks similar to 50 ohm but I'm not sure. Any suggestions would be appreciated. About coax impedance, When you just have a (VHF) transmitter with 50 Ohm VSWR meter and external dummy load, you can do the following: Check whether the insulation (between inner and outer conductor) is solid or not (may be foam). Check whether the insulation (between inner and outer conductor) melts (changes color to transparent) at relative low temperature. If solid, the velocity factor is about 0.66, when foam, it will be about 0.79..0.84 If it melts at relative low temperature it is very likely Polyethyleen (PE) insulation, if not, it is PTFE (Teflon). Based on your transmission frequency and the velocity factor, cut an electrically quarter wave. Terminate the cable with the 50 Ohms dummy load and connect the cable to the VSWR meter. Measure the VSWR of the cable/dummy load combination. When VSWR is almost one, you can be sure it is 50 Ohms cable. When it is about 2.2, it will be 75 Ohms cable. When it has VSWR close to 3.5, it is probably 93 Ohms cable. This is based on: Zload*Zinput = Zcalbe^2 for a quarter wave line. When these measurements matches the mechanical identification of Tom's posting, you can be very sure about the impedance of the cable. Best Regards, Wim PA3DJS |
Identifying coax cable.
Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? Sure, attach it to a dummy load and see if you get a perfect 1:1 swr. There are lots of other ways but this is simplest. |
Identifying coax cable.
Boozo wrote:
Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? If it is aluminum, it may be 75 ohm cable TV coax. -- 73, Cecil http://www.w5dxp.com |
Identifying coax cable.
"Boozo" wrote in message ups.com... Have a 100 foot roll(approx) of used coax cable which has no markings printed on it. Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? Going by the size it looks similar to 50 ohm but I'm not sure. Any suggestions would be appreciated. If it has a solid center conductor, it is almost certainly 75 Ohm. The only exception I can think of is some weird version of RG58. Tam |
Identifying coax cable.
Tam/WB2TT wrote: "Boozo" wrote in message ups.com... Have a 100 foot roll(approx) of used coax cable which has no markings printed on it. Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? Going by the size it looks similar to 50 ohm but I'm not sure. Any suggestions would be appreciated. If it has a solid center conductor, it is almost certainly 75 Ohm. The only exception I can think of is some weird version of RG58. Tam I do have a bunch of older RG-58 with solid center conductor, and pretty much all the HP BNC patch cables I've seen the insides of have a solid center. I believe the various semi-official versions (RG-58/U, RG-58A/U, RG-58B/U and RG-58C/U) tell whether the center is supposed to be solid or stranded, but that seems to have become *******ized. A quick Google search for RG58A yields cables with both solid and stranded centers. How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume the poster would have mentioned the strange construction. Also, you're likely to find a solid center in higher impedance line like RG62/U, and you're likely to find stranded center on 75 ohm line (like RG-11/U, and others). And of course for some surplus custom line, all bets are off about both stranding and impedance! Cheers, Tom |
Identifying coax cable.
If it has a solid center conductor, it is almost certainly 75 Ohm. The only exception I can think of is some weird version of RG58. Tam I do have a bunch of older RG-58 with solid center conductor, and pretty much all the HP BNC patch cables I've seen the insides of have a solid center. I believe the various semi-official versions (RG-58/U, RG-58A/U, RG-58B/U and RG-58C/U) tell whether the center is supposed to be solid or stranded, but that seems to have become *******ized. A quick Google search for RG58A yields cables with both solid and stranded centers. How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume the poster would have mentioned the strange construction. Also, you're likely to find a solid center in higher impedance line like RG62/U, and you're likely to find stranded center on 75 ohm line (like RG-11/U, and others). And of course for some surplus custom line, all bets are off about both stranding and impedance! Cheers, Tom Well, I was going to avoid this, but when you chimed in Tom, couldn't help myself. In turn, I have a large helping of a Times Wire and Cable RG-8 size 50 Ohm coax with a solid inner conductor. Don't remember their nomenclature for it but it's a real bear getting "N" connectors onto it.. W4ZCB |
Identifying coax cable.
In article . com,
"Boozo" wrote: Have a 100 foot roll(approx) of used coax cable which has no markings printed on it. Can anyone tell me how I can work out what it might be ? e.g. 75 ohm or 50 ohm or ? Going by the size it looks similar to 50 ohm but I'm not sure. Any suggestions would be appreciated. just a note, lots of cable have sold conductors at 50ohms times microwave and andrews cinta are examples |
Identifying coax cable.
"Harold E. Johnson" wrote in message news:A1N1h.261969$1i1.61365@attbi_s72... If it has a solid center conductor, it is almost certainly 75 Ohm. The only exception I can think of is some weird version of RG58. Tam I do have a bunch of older RG-58 with solid center conductor, and pretty much all the HP BNC patch cables I've seen the insides of have a solid center. I believe the various semi-official versions (RG-58/U, RG-58A/U, RG-58B/U and RG-58C/U) tell whether the center is supposed to be solid or stranded, but that seems to have become *******ized. A quick Google search for RG58A yields cables with both solid and stranded centers. How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume the poster would have mentioned the strange construction. Also, you're likely to find a solid center in higher impedance line like RG62/U, and you're likely to find stranded center on 75 ohm line (like RG-11/U, and others). And of course for some surplus custom line, all bets are off about both stranding and impedance! Cheers, Tom Well, I was going to avoid this, but when you chimed in Tom, couldn't help myself. In turn, I have a large helping of a Times Wire and Cable RG-8 size 50 Ohm coax with a solid inner conductor. Don't remember their nomenclature for it but it's a real bear getting "N" connectors onto it.. W4ZCB Solid could be 92 ohms too. |
Identifying coax cable.
Have a 100 foot roll(approx) of used coax cable which has no markings....
I do have a bunch of older RG-58 with solid center conductor, and ....[snip].... .... How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume .... For those of us who never noticed -- or never recognized -- the difference in the first place, could you please explain what I should have recognized? --Myron -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor Certified Instructor for the Kansas Concealed-Carry Handgun license |
Identifying coax cable.
wrote in message ... Have a 100 foot roll(approx) of used coax cable which has no markings.... I do have a bunch of older RG-58 with solid center conductor, and ....[snip].... .... How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume .... For those of us who never noticed -- or never recognized -- the difference in the first place, could you please explain what I should have recognized? --Myron -- The outside diameter of the cable, like .195, .240, .260, .405,... and the gage of the center conductor, like #10, 14, 16, 18, stranded or solid. Tam --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor Certified Instructor for the Kansas Concealed-Carry Handgun license |
Identifying coax cable.
.... How about Belden 9913? Of course, the construction of that line
is "different" enough that it would be hard to mistake it for something else, and I assume .... For those of us who never noticed -- or never recognized -- the 9913 differences in the first place, could you please explain.... The outside diameter of the cable, like .195, .240, .260, .405,... and the gage of the center conductor, like #10, 14, 16, 18, stranded or solid. I don't understand. Are you saying 9913 has been made in ALL of those different sizes and with ALL of those different center- conductor gauges? -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor Certified Instructor for the Kansas Concealed-Carry Handgun license |
Identifying coax cable.
wrote in message ... .... How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume .... For those of us who never noticed -- or never recognized -- the 9913 differences in the first place, could you please explain.... The outside diameter of the cable, like .195, .240, .260, .405,... and the gage of the center conductor, like #10, 14, 16, 18, stranded or solid. I don't understand. Are you saying 9913 has been made in ALL of those different sizes and with ALL of those different center- conductor gauges? Sorry, I thought you were talking about the original question. The base 9913 is #10 solid. 9913 Flex is stranded. Tam -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor Certified Instructor for the Kansas Concealed-Carry Handgun license |
Identifying coax cable.
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Identifying coax cable.
On 3 Nov 2006 14:52:12 -0800, K7ITM wrote:
....... but rather with the form the dielectric takes. It's a polyethylene tube with fairly thin wall that supports the outer conductor, and inside that, a "thread" of polyethylene with a diameter half the difference between the inner conductor diameter and the ID of the polyethylene tube, which is formed in a spiral to support the inner conductor coaxially with the outer conductor. That sounds like RG-62 (93 ohm). Video terminal cable -- 3270 and that ilk. But, since none of the mind readers in this ng have yet to post the dimensions, it's only a data point so far. Jonesy -- Marvin L Jones | jonz | W3DHJ | linux 38.24N 104.55W | @ config.com | Jonesy | OS/2 *** Killfiling google posts: http//jonz.net/ng.htm |
Identifying coax cable.
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sc continues crapathon
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Identifying coax cable.
"Boozo" wrote in message ... "Slow Code" wrote in message nk.net... wrote in : .... How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume .... For those of us who never noticed -- or never recognized -- the 9913 differences in the first place, could you please explain.... The outside diameter of the cable, like .195, .240, .260, .405,... and the gage of the center conductor, like #10, 14, 16, 18, stranded or solid. I don't understand. Are you saying 9913 has been made in ALL of those different sizes and with ALL of those different center- conductor gauges? Just go to Radio Shack. You can exchange blank stares with the clerk. SC Looks like I may have to as it doesn't seem to have an easy solution and my VHF transmitter is broken. Have a data sheet handy so might take some measurements with the vernier calipers and see what I come up with. Thanks for all the suggestions. Boozo.(nothing to do with alcohol !) the original 9913 has a 9.5ga solid copper center conductor, the center conductor has a spiral wrapped standoff insulator, a thin solid dielectric layer then foil and braid shield. the od is .405" so it can't be easily distinguished from regular rg8 without looking inside. though if it is the original good stuff i would expect it to be well marked on the outside since not just everyone made it. the problem is that there have been many variations over the years on 9913, including stranded center conductors and some variations in dielectrics. |
"Slow Code"...I Owe You A Cold One! Thanks!
Slow Code wrote: wrote in : .... How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume .... For those of us who never noticed -- or never recognized -- the 9913 differences in the first place, could you please explain.... The outside diameter of the cable, like .195, .240, .260, .405,... and the gage of the center conductor, like #10, 14, 16, 18, stranded or solid. I don't understand. Are you saying 9913 has been made in ALL of those different sizes and with ALL of those different center- conductor gauges? Just go to Radio Shack. You can exchange blank stares with the clerk. BBBBWWWHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAH AHAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHAHA !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!! R O T M F F L M M F A O ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! I haven't laughed that hard in a while! Thanks! Steve, K4YZ |
"Slow Code"...I Owe You A Cold One! Thanks!
Mark in the Dark, wrote in
: On 6 Nov 2006 00:03:19 -0800, "K4YZ" wrote: Slow Code wrote: wrote in : .... How about Belden 9913? Of course, the construction of that line is "different" enough that it would be hard to mistake it for something else, and I assume .... For those of us who never noticed -- or never recognized -- the 9913 differences in the first place, could you please explain.... The outside diameter of the cable, like .195, .240, .260, .405,... and the gage of the center conductor, like #10, 14, 16, 18, stranded or solid. I don't understand. Are you saying 9913 has been made in ALL of those different sizes and with ALL of those different center- conductor gauges? Just go to Radio Shack. You can exchange blank stares with the clerk. BBBBWWWHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAH AHAHAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHAHA HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA HAHAHAHAHA !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!! R O T M F F L M M F A O ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! I haven't laughed that hard in a while! yes we know you like degrading everyione arround you Shut up Markie. You can't even spell 'coax.' SC |
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