Hi Scott,
The "cu" stands for copper & I don't have a clue. I just know to order "cu" and I am sure to get the stranded cable. That's what is printed on the cable.
RG-58 is often used in RF connectors that are crimped or soldered (BNC, N ...), but I've not seen RG-59 used in anything that doesn't use the center conductor as the connection point. You never know though. I just learned that stranded RG-59 exists - from you. I do have some heavier, stranded 75R RF cable. It's like RG-6 in diameter with a stranded core. I rarely use it.
-Chris
The "cu" stands for copper & I don't have a clue. I just know to order "cu" and I am sure to get the stranded cable. That's what is printed on the cable.
RG-58 is often used in RF connectors that are crimped or soldered (BNC, N ...), but I've not seen RG-59 used in anything that doesn't use the center conductor as the connection point. You never know though. I just learned that stranded RG-59 exists - from you. I do have some heavier, stranded 75R RF cable. It's like RG-6 in diameter with a stranded core. I rarely use it.
-Chris
All RG-xxx standards have been retracted 30 years ago. They stem from WW2 times.
Every manufacturer is free to call its stuff now RG-xxx, and they do it for whatever
they have. Usually the shield has less Cu, so radiation / pick up suffers.
RG stood for Radio Guide.
The only working way is to buy from a recognized manufacturer and to believe his
data sheets.
Some important RG cabels are:
RG-174 abt. 3 mm o.d. polyethylene
RG-188 same but silver plated and Teflon (You cannot use tin in teflon cables
because it would melt at the temperature needed to extrude Teflon)
RG-58, we had that already
RG-59 some higher impedance
RG-8, RG-213 Polyethylene, abt. 10 mm OD. Hams use it to shove their KW
to the antenna.
RG-223 better quality teflon 5mm or so; i think it also has a foil for shielding.
not RG, but I like it: UT-141 141mil semi rigid , teflon, solid center,
shield is a solid tube, for permanent installation in devices. Fits SMA.
There is also a 5 mm version that is common.
And there is SF-50, just a little bit more than a mm OD. Teflon/Cu/Ag
with solid center. Fits into our SMD world. I love it, though I have
found no connectors for it up to now.
I don't think that CU stands for copper; it used to be written c/u.
I have a 40 year old ARRL handbook, but it is 200 miles away.
It has a good chapter on that stuff.
regards, Gerhard
Every manufacturer is free to call its stuff now RG-xxx, and they do it for whatever
they have. Usually the shield has less Cu, so radiation / pick up suffers.
RG stood for Radio Guide.
The only working way is to buy from a recognized manufacturer and to believe his
data sheets.
Some important RG cabels are:
RG-174 abt. 3 mm o.d. polyethylene
RG-188 same but silver plated and Teflon (You cannot use tin in teflon cables
because it would melt at the temperature needed to extrude Teflon)
RG-58, we had that already
RG-59 some higher impedance
RG-8, RG-213 Polyethylene, abt. 10 mm OD. Hams use it to shove their KW
to the antenna.
RG-223 better quality teflon 5mm or so; i think it also has a foil for shielding.
not RG, but I like it: UT-141 141mil semi rigid , teflon, solid center,
shield is a solid tube, for permanent installation in devices. Fits SMA.
There is also a 5 mm version that is common.
And there is SF-50, just a little bit more than a mm OD. Teflon/Cu/Ag
with solid center. Fits into our SMD world. I love it, though I have
found no connectors for it up to now.
I don't think that CU stands for copper; it used to be written c/u.
I have a 40 year old ARRL handbook, but it is 200 miles away.
It has a good chapter on that stuff.
regards, Gerhard
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Thanks Gerhard,
For television distribution systems in the US a variant based on RG6 is used for individual drops. It has a copper plated steel center conductor and four layers of shields. Two are woven aluminum braid of perhaps 60-80% coverage and two are foil. Cheap folks and satellite use only one of each.
Virtual all of the cable is the "U" variety which stands for uncontaminating. Very old stuff did not age well and the plastic characteristics changed so it had to be replaced every few years.
The main trunk cable is semirigid. It is an aluminum tube with a copper plated steel center conductor. The stuff is rated by diameter and I seem to recall using .520 & .75" stuff or there abouts. The center conductor is about 12 gauge. It comes in 1/2 mile spools as that is as far as you can send signal before a booster amplifier is required. The practical limit for TV distribution is three amplifiers before distortion degrades the signal too much for the multi-multi channel systems.
The plant to make the cable is also 1/2 mile long! No wonder fiber is now used for most city wide distribution.
The heaviest duty coax for broadcast use is actually made from copper plumbing pipe! For the largest I have used the outer conductor is 3" copper tubing and there are plastic spacers with not just a center hole but also others to allow dry nitrogen gas to pass to a pressure relief valve at the end of the antenna. The inner conductor is 3/4" or 1/2" pipe depending on impedance!
Special split pin connectors are used to join sections of the inner conductor. The outer conductor does have to stay gas tight.
For small systems a tank of nitrogen is used to purge the line and a slightly above atmospheric pressure is maintained. This is monitored by a gauge.
For larger leakier systems an air compressor and dryer are used.
For television distribution systems in the US a variant based on RG6 is used for individual drops. It has a copper plated steel center conductor and four layers of shields. Two are woven aluminum braid of perhaps 60-80% coverage and two are foil. Cheap folks and satellite use only one of each.
Virtual all of the cable is the "U" variety which stands for uncontaminating. Very old stuff did not age well and the plastic characteristics changed so it had to be replaced every few years.
The main trunk cable is semirigid. It is an aluminum tube with a copper plated steel center conductor. The stuff is rated by diameter and I seem to recall using .520 & .75" stuff or there abouts. The center conductor is about 12 gauge. It comes in 1/2 mile spools as that is as far as you can send signal before a booster amplifier is required. The practical limit for TV distribution is three amplifiers before distortion degrades the signal too much for the multi-multi channel systems.
The plant to make the cable is also 1/2 mile long! No wonder fiber is now used for most city wide distribution.
The heaviest duty coax for broadcast use is actually made from copper plumbing pipe! For the largest I have used the outer conductor is 3" copper tubing and there are plastic spacers with not just a center hole but also others to allow dry nitrogen gas to pass to a pressure relief valve at the end of the antenna. The inner conductor is 3/4" or 1/2" pipe depending on impedance!
Special split pin connectors are used to join sections of the inner conductor. The outer conductor does have to stay gas tight.
For small systems a tank of nitrogen is used to purge the line and a slightly above atmospheric pressure is maintained. This is monitored by a gauge.
For larger leakier systems an air compressor and dryer are used.
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Thanks for the info on coax. It's strange that they would print a wire gauge on it but not correspond with resistances. The number must have some other correspondence.
Just like the Reeperbahn in Hamburg, where they used to make ropes for the ships.
(now the red light district)
Close to where I live there was one of the strongest MW transmitters in Germany.
Actually, you could listen to Luxemburg and Europawelle Saar anywhere in the
mediterranian region, and nothing else in German language. (1422 KHz).
They pumped 1.6 MW into the air and had to shield a nearby Autobahn since
a lot of cars broke down that had transistor ignition. 😀
The antenna had a reflector tower so that the Russians would get less and Spain more 🙂
Gerhard
Thanks gerhard,
That was illuminating. I've seen some equipment that was copper tubing (no, it wasn't a still!). I've been told that once you get used to working with the tubing it wasn't that bad to work with.
-Chris
That was illuminating. I've seen some equipment that was copper tubing (no, it wasn't a still!). I've been told that once you get used to working with the tubing it wasn't that bad to work with.
-Chris
Gerhard,
1.6 MW! My guess is that would be ERP (Effective Radiated Power). Antennas sometimes have as many as 32 bays which change the coverage from the spherical pattern of a single bay to an almost perfect circular plain. This reduced coverage area give a gain of perhaps 15. A more normal 6 bay antenna is a bit above 3.
The actual transmitter power could range from 100-500 KW. With something in the middle around 300 KW that would require a voltage in the transmission line of around 4,000 volts! So with good dry air in the line they probably would just barely get away with a 3" line!
Of course I wouldn't climb the antenna tower during use!
Quite impressive!
Of course if you lived nearby you wouldn't need to pay any light bill. Fluorescent tubes without any connections would light up! Turning off of the lights would require placing the tubes in the closet!
1.6 MW! My guess is that would be ERP (Effective Radiated Power). Antennas sometimes have as many as 32 bays which change the coverage from the spherical pattern of a single bay to an almost perfect circular plain. This reduced coverage area give a gain of perhaps 15. A more normal 6 bay antenna is a bit above 3.
The actual transmitter power could range from 100-500 KW. With something in the middle around 300 KW that would require a voltage in the transmission line of around 4,000 volts! So with good dry air in the line they probably would just barely get away with a 3" line!
Of course I wouldn't climb the antenna tower during use!
Quite impressive!
Of course if you lived nearby you wouldn't need to pay any light bill. Fluorescent tubes without any connections would light up! Turning off of the lights would require placing the tubes in the closet!
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Its skin effect. The wire gauge is useful for finding matching connectors. The core diameter affects the RF loss as does the insulator and the shield. Solid core silver plated usually has the lowest loss. The steel is for strength (not cost savings except for cheap consumer cables) so the cables hold up under stress.
Most CATV cable plants use quad shield RG6 for drops an in home applications. Quad has two layers of braid and two layers of foil. The FCC requirements for low leakage pushed them into this.
The OD of the cable works back from the center conductor diameter, the insulator and the impedance spec. The vendor adjusts it to get the target impedance and needs to keep checking in production. If they get sloppy the consequences can be serious. One vendor had a small bump on a roller. It knocked out some satellite channels but not the adjacent ones. Really high q filter. It was discovered after the cables were pulled in walls. Very expensive to fix.
No, that's 1.6 MW as seen on your dBm meter 🙂 Actually, it was 2 transmitters,
400 KW and 1200 KW. They used either one of these or combined them together
with a phase bridge. Someone of our ham radio club used to work there.
I was told there was even a casualty when they built the large indoor pool in the
nearby village when someone grabbed the steel cable hanging from a crane.
I assume that the idea of the pool came from the warm water supply. It's a small
village after all, not a place where you would expect a large public pool.
The tubes may have been Thompson-CSF Hypervapotrons, but I'm not sure after
all that time. My home is located 30 Km from there, so I'm not in immediate danger.
I'm not even sure if they still operate it, absolutely nobody listenes to AM any more here.
shielded highway:
< https://de.wikipedia.org/wiki/Sender_Heusweiler#/media/File:Faradayscher_Käfig_Heusweiler_0685.jpg >
In the Wiki, they write 1200 KW:
< https://de.wikipedia.org/wiki/Sender_Heusweiler >
And they did shut it down a year ago.
🙂 Gerhard
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Actually I am completely off! I didn't expect AM. Much harder to get antenna gain! So who paid the electric bill? 🙂
The local 50 KW station easily used to travel 500-1000 miles so 1.6 MW should cover half the planet!
The local 50 KW station easily used to travel 500-1000 miles so 1.6 MW should cover half the planet!
At one of the sites I helped build we used 9" coax. 5 full power FM transmitters (50kW each) multiplexed into the final 9" up the tower to a panel antenna.
at the other site we only had 3 stations and we used 6" up the tower.
Both of these used trombones I built to do the final fine tuning. What's a trombone? just like it says, variable length to vary the distance on one of the lines to match another.
Glad I don't do that stuff anymore. Mic preamps are much easier to put on the bench.
Cheers,
Alan
at the other site we only had 3 stations and we used 6" up the tower.
Both of these used trombones I built to do the final fine tuning. What's a trombone? just like it says, variable length to vary the distance on one of the lines to match another.
Glad I don't do that stuff anymore. Mic preamps are much easier to put on the bench.
Cheers,
Alan
Back when I was a grad working on Satellites they were very hot on EMC as bad things happen when you get issues! That autobahn was one of the examples given, although at the time they claimed BMW paid for it as was cheaper to screen the road than the cares.
Proper RF is fun. You know the sort of stuff where you used to measure RF power in terms of kg of water needed for cooling rather than ERP 🙂
Proper RF is fun. You know the sort of stuff where you used to measure RF power in terms of kg of water needed for cooling rather than ERP 🙂
Message for RNMarsh and jackinnj :
http://www.diyaudio.com/forums/soli...se-measurement-amp-ikoflexer.html#post4898911
Cheers,
Patrick
http://www.diyaudio.com/forums/soli...se-measurement-amp-ikoflexer.html#post4898911
Cheers,
Patrick
My favorite story was the guy that pioneered bare handed maintenance on 750kV transmission lines. Someone had to convince himself that it would work and actually try and not become a vaporized squirrel.
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Yeah, crazy stuff. Here they use helicopters to wash insulators as per this video - 'Hot-Washing' the Insulators of a 500,000 Volt Power Line!.
This stuff is really crazy - Helicopter Maintenance on energized 765,000 Volt Line
Dan.
We've had a few grid maintenance customers, crazy stuff yes, one wanted to know if massively parallel MEMS switches could replace the transformer cut-off switches which need explosive charges to force them open against the fusing current.
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