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Coax?

S

solderjerk

Member
May 4, 2007
23
0
11
Shingletown Ca.
I picked up some coax at a yard sale and can't find what the ohm value is. Somebody taped on a piece of RG-58 to the end of it (what a dork). I looked on the internet and can't find anything about it. The coax is about the same size as RG-8 but has a solid copper shield and the center conductor is solid copper about twice the size of RG-8. On the coax it say's ( NK COMMUNICATIONS RF 1/2"-50 15/99 00148 M). I've got about 70 ft. of this stuff, if anyone knows if this can be used for a CB let me know. (I think it's 50 ohms but not sure). Thanks :shock:
 

Gotta love GOOGLE :LOL: Sorry to say but it looks like what is called radiating coax,in other words it is designed to leak RF all over the place.It is commonly used in large buildings like hospitals etc. where radio communications are hard due to the cement and steel construction. A long run is made down halways etc and acts like an antenna for the RX/TX and allows RF to enter and exit all along the way. No good for normal 2-way comms.
 
Did you even look at the link I posted above? It IS 50 ohm cable but it's RADIATING COAX CABLE. No good for normal radio use.The shield has holes all along it's length.
 
The idea is to check the SWR into a known 50 load. If it's close to 1.0:1 then it's '50 ohm' coax. If it's something like 1.5:1 then it's either 75 ohm or 25 ohm stuff.
If QRN is right (no reason to doubt it!), you can keep 'my' share of it - lol.
- 'Doc

Got a 'wireless' system? One end of that stuff close to the antenna, string the rest to where you want to get the signal.
 
You could take a few inches apart and see if it has the holes in it like QRN's link suggested. How hard is that?
 
maybe you could strip off all the outer jacket and solder up all those holes and have something like hardline?

Actually that would probably be good stuff for extending your wi-fi AP out to the shop.
 
I checked and there aren't any holes or slots in it so I guess it's hard line. I did some more checking and it is 50 ohm. The center conductor is 3/16" thick. The dialectric isn't foam it's plastic (I guess). The cable itself is 5/8" diameter. I'm pretty sure it was used for tower hardline for (wireless-cellular-microwave). The db loss gets higher the higher you go in frequency, and about 27 meg. there's hardly any loss at all. The stuff costs about 5 bucks a foot. I guess it uses a N connector, I'll just put a PL-259 adaptor on it. Hey, I'll give it a shot and see what happens.
 
As long as you use it well below 150 MHz, the slots in the cuprous shield shouldn't leak too badly. The stuff I've seen has very precise slots (not circular holes) through which RF can pass if its wavelength will fit through. Probably not bad for HF, but nothing higher.
 
The coax is 50 ohms.

The -50 designator gives it away.

This stuff sounds VERY similar to Andrew Heliax LDF1-50 coax.
RFS also make a very similar coax RFS12-50
You guess it 12 means 1/2 inch and -50 is 50 ohms.

You can find the specs for these cables on their manufacture's websites.

If you can't find connectors for them, you might find that your RG8 connectors will fit nicely with the use of a small needle file.
 
solderjerk said:
I said there ARE NOT any holes or slots in the coax, but thanks for the info.
Click to expand...

OK I have the proper cable HERE. Sorry about that,the first one I had linked to above had an "X" in the number I missed and it was a radiating cable. This one above is not and I believ it is the same cable you have.
 

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