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Making ones own coax cable

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#1
Just curious if anyone has made there own coax or know someone who has. How well did it work for you? I don't mean fit on a connector but to actually put an insulating material around a center conductor and then put some braid over the dielectric and then a jacket over all that for a certain length. Or at least some of those steps.

How well would coax recieve/transmit if all there was was the center conductor hooked to a connector on each end and to your radio and antenna? I would think it would be to noisy or would probably short easy with no dielectric at least.

Not sure if there would be any advantages to making your own. Lower cost? It would be neat to try though.
 

mmckenna

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#2
Some people have made their own hardline out of copper pipe and a center conductor of rod or wire.

Getting the spacing and sizes correct is critical for its characteristic impedance.
It can be quite a lot of work to do it right. Copper pipe isn't cheap, the materials to get the spacing correct are not cheap.
And it's pretty easy to get really good coaxial cable now fairly inexpensively. So there's not a whole lot of sense in making your own coax, other than bragging rights.

It's certainly possible to do.

More commonly what you'll find is people utilizing old cable TV hard line. You can often get long lengths of it cheap or free as systems are upgraded to fiber.
You can even find fairly inexpensive batches of high end cable like Heliax pretty cheap if you look around.

Making your own flexible coax would be more of a challenge. Not sure it's really worth it.
 
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#3
Some people have made their own hardline out of copper pipe and a center conductor of rod or wire
Getting the spacing and sizes correct is critical for its characteristic impedance.
It can be quite a lot of work to do it right. Copper pipe isn't cheap, the materials to get the spacing correct are not cheap.
And it's pretty easy to get really good coaxial cable now fairly inexpensively. So there's not a whole lot of sense in making your own coax, other than bragging rights.It's certainly possible to do.
Sounds like a challenge and like it could be frustrating, but perhaps worth a try sometime.

More commonly what you'll find is people utilizing old cable TV hard line. You can often get long lengths of it cheap or free as systems are upgraded to fiber.
You can even find fairly inexpensive batches of high end cable like Heliax pretty cheap if you look around.
That's good to keep in mind, be sad if it went to the landfill before it's time.


Making your own flexible coax would be more of a challenge. Not sure it's really worth it.
For some people maybe, for some people.
 

GMB951

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#4
I ordered a broadband single amp and it came from china the problem is it very small connector's on it does anybody know what size cable this is or were you could get adapters to fit with normal RG TV type cable to connect to my BCD 996P2 never dealt with cable or connector this small
 
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#5
Just curious if anyone has made there own coax or know someone who has. How well did it work for you?
I've made rigid coax out of hobby brass tubing. Careful selection of sizes can give you various characteristic impedances, which is important when making things like power dividers.

All in all, it worked quite well.

How well would coax recieve/transmit if all there was was the center conductor hooked to a connector on each end and to your radio and antenna?
That would be an antenna, not coax which, by definition, is a center conductor with a shield. There IS a variation of your idea called G-line that was once widely used in cable TV distribution. It was a single open wire with funnel-like launchers on each end. It works quite well.

Not sure if there would be any advantages to making your own. Lower cost? It would be neat to try though.
Cost wouldn't be a good motivation for making your own. Good coax can be found for cheap. But good luck finding 36 or 93 ohm coax, or whatever you might need. In that case, making your own becomes reasonable.
 
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#6
I ordered a broadband single amp and it came from china the problem is it very small connector's on it does anybody know what size cable this is or were you could get adapters to fit with normal RG TV type cable to connect to my BCD 996P2 never dealt with cable or connector this small
It's probably SMA connectors, the same type that most modern portable scanners use.
There are both adaptors and pigtails available to convert to all sorts of connector types including F and BNC.

/Ubbe

https://www.ebay.com/itm/F-Type-Female-Jack-To-SMA-Male-Plug-Coaxial-Connector-Adapter/272331416743
https://www.ebay.com/itm/30cm-RG316...-male-plug-jumper-pigtail-12inch/192647705431


 
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#8
I've made rigid coax out of hobby brass tubing. Careful selection of sizes can give you various characteristic impedances, which is important when making things like power dividers.
All in all, it worked quite well.
Interesting. I believe brass is suppose to be one of the best conducting metals as well. Did you put an insulator, shield or jacket over it? I wonder if a tube would conduct as well as single or stranded wire or have more of a skin effect? Not sure how you would check that. You might notice though. What setup did you use the ridgid coax for?

That would be an antenna, not coax which, by definition, is a center conductor with a shield. There IS a variation of your idea called G-line that was once widely used in cable TV distribution. It was a single open wire with funnel-like launchers on each end. It works quite well.
Yeah I worded that badly, meant to say how well will the transceiver receieve/transmit if you only used a center conducter hooked up to the transceiver and antenna. Juat a bare or insulated wire with a connector soldered to each end. Not to well I imagine.

Cost wouldn't be a good motivation for making your own. Good coax can be found for cheap. But good luck finding 36 or 93 ohm coax, or whatever you might need. In that case, making your own becomes reasonable.
That could come in handy if you don't have or wanna use an antenna tuner.
 
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#10
Interesting. I believe brass is suppose to be one of the best conducting metals as well. Did you put an insulator, shield or jacket over it?
Yes, brass works quite well. I've used the thick, adhesive type heat shrink tubing to cover it. I've also left it bare.

I wonder if a tube would conduct as well as single or stranded wire or have more of a skin effect? Not sure how you would check that. You might notice though.
For RF, tubing works just fine. The skin effect is pronounced enough that being hollow has no adverse impact, and in fact probably works better because RF currents will flow on both the inside and outside surfaces of the tubing.

What setup did you use the ridgid coax for?.
Several things... I've built impedance matching lines, power dividers, and an unusual device called a line stretcher that uses telescoping sections to change the length of the transmission line. I've also built adapters where I need, say, an N male connector on one end and a female TNC on the other with 4 inches of coax in between. If it's in an amplifier running a few hundred watts, and RG58 isn't sufficient and RG8 is too difficult to work such a short length, making a custom adapter starts to make sense. Not coax, but I've also built microwave waveguide out of copper water pipe.

Yeah I worded that badly, meant to say how well will the transceiver receieve/transmit if you only used a center conducter hooked up to the transceiver and antenna. Juat a bare or insulated wire with a connector soldered to each end. Not to well I imagine.
No, I thought you worded it just fine, hence my answer. Without the outer shield, that center conductor will radiate just like an antenna, so the antenna would start right at the back of the radio. Very little energy would reach the actual antenna.

That could come in handy if you don't have or wanna use an antenna tuner.
Possibly, but usually coaxial matching sections are a fixed part of a more complex antenna system. Phased folded dipole collinear arrays might need some unusual impedance of coax to act as an impedance transformer, for example.

In that application, it's not a choice of that or an antenna tuner. The tuner just doesn't apply. Same thing with a power divider where a 50 ohm coax must attach to two 50 ohm antennas. Making a coaxial section of a specific impedance for a specific length will transform the impedance to pretty much whatever you need it to be.
 
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#11
I have made a short length - about 18 inches - of double screened coax by carefully pulling the centre conductor and insulator from a piece of RG8 - the centre insulator is smooth and so doesn't grip the shield - then inserting a length of RG58 down the hole - well, pulled it through very carefully - had to make another as the mistake was to solder both inner and outer braids together at both ends. The best screening was with only one end connected at the source.
 

bob550

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#12
Many years ago, I had a friend who thought about building his own car from parts. When he roughly estimated the cost, he was quickly convinced that it was far cheaper to buy than to build one himself. If there were readily available components, and if you knew exactly what you were doing, and if you possessed enough knowledge to guarantee the resulting transmitting and/or receiving performance, maybe it might be sensible. But remember that the time required to complete such a project is time you could better spend enjoying your radio.
 

mmckenna

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#13
Many years ago, I had a friend who thought about building his own car from parts. When he roughly estimated the cost, he was quickly convinced that it was far cheaper to buy than to build one himself. If there were readily available components, and if you knew exactly what you were doing, and if you possessed enough knowledge to guarantee the resulting transmitting and/or receiving performance, maybe it might be sensible. But remember that the time required to complete such a project is time you could better spend enjoying your radio.
His name wasn't Johnny Cash was it?
https://www.youtube.com/watch?v=060A15ELz00
 
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#14
Yes, brass works quite well. I've used the thick, adhesive type heat shrink tubing to cover it. I've also left it bare.
Good to hear. That doesn't present any kind of fire hazard? How much power have you ran through it? It won't short I suppose unless it touch something metal.

For RF, tubing works just fine. The skin effect is pronounced enough that being hollow has no adverse impact, and in fact probably works better because RF currents will flow on both the inside and outside surfaces of the tubing.
Hmmm. That's good.

Several things... I've built impedance matching lines, power dividers, and an unusual device called a line stretcher that uses telescoping sections to change the length of the transmission line. I've also built adapters where I need, say, an N male connector on one end and a female TNC on the other with 4 inches of coax in between. If it's in an amplifier running a few hundred watts, and RG58 isn't sufficient and RG8 is too difficult to work such a short length, making a custom adapter starts to make sense. Not coax, but I've also built microwave waveguide out of copper water pipe.
I've got to look into those more. Those waveguides sound neat and that line stretcher, never heard of it until now.I like my telescoping antennas. Never heard of a TNC either. Gonna stock up on those.How come RG-58 wouldn't be sufficient? .

No, I thought you worded it just fine, hence my answer. Without the outer shield, that center conductor will radiate just like an antenna, so the antenna would start right at the back of the radio. Very little energy would reach the actual antenna.
.

Ahh, right. I should have realized that. Guess I was thinking that the center conductor in the coax wouldn't radiate or something, but apparently any metal will if it doesn't have a shield around it. Except for maybe that G-line stuff but I don't know about that yet.

Possibly, but usually coaxial matching sections are a fixed part of a more complex antenna system. Phased folded dipole collinear arrays might need some unusual impedance of coax to act as an impedance transformer, for example.
In that application, it's not a choice of that or an antenna tuner. The tuner just doesn't apply. Same thing with a power divider where a 50 ohm coax must attach to two 50 ohm antennas. Making a coaxial section of a specific impedance for a specific length will transform the impedance to pretty much whatever you need it to be.
Okay gotcha,

I have made a short length - about 18 inches - of double screened coax by carefully pulling the centre conductor and insulator from a piece of RG8 - the centre insulator is smooth and so doesn't grip the shield - then inserting a length of RG58 down the hole - well, pulled it through very carefully - had to make another as the mistake was to solder both inner and outer braids together at both ends. The best screening was with only one end connected at the source.
What made you want to double shield the coax? What setup was it for? Hmm, wouldn't think they would need to be soldered to each other. I guess your hooking the braid up to one end of a dipole though you'd want them both together. You mean you got the best results from soldering the braids or screens just at the source end? Was it worth the effort?

Many years ago, I had a friend who thought about building his own car from parts. When he roughly estimated the cost, he was quickly convinced that it was far cheaper to buy than to build one himself. If there were readily available components, and if you knew exactly what you were doing, and if you possessed enough knowledge to guarantee the resulting transmitting and/or receiving performance, maybe it might be sensible. But remember that the time required to complete such a project is time you could better spend enjoying your radio.
I guess it's about balancing out what you value the most. Playing around with your rig, or experimenting with stuff, trying to build things.

Wouldn't say I'm a fan of his but he has some alright music.
 
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