RG6 Solid Conductor or Copper Coated Steel

[gray1]

This is my first post so be kind. I am redoing my scanner antenna after many years and would like some input. I have a Radio Shack Discone antenna and am goin to buy a Uniden
BT8C scanner. I went to my local Lowes and bought the best RG6 coax I could buy. It is Philips RG6 Quad Core with popon connecters. It has a copper coated steel center conductor. But I got to thinking. I Believe RG58U and RG8U all had solid copper conductors.
I found a guy on E-Bay thats got Perfect Vision RG6 Quad Shield solid copper conductor that is priced reasonable. It would seem to me that the Solid Copper Conductor would be better in the lower ranges. Is this correct? Does it even make a difference?

Thanks for any and all advise:

Gray1

 

[prcguy]

Copper clad steel and solid copper center conductors have identical RF properties in the frequency range for scanner use because RF above several MHz travels on the skin of the conductors and generally does not penetrate to the steel core. Directv and Dish Network call out solid copper center conductors only for low DC resistance when powering LNBs, multi-switches, etc. The lower DC voltage drop using solid copper center conductor will allow a slightly farther coax run for these systems but there is no performance benefit otherwise. Quad shield is a bit overkill for scanner use, the loss is identical to single shield if comparing the same brand and quality.
prcguy

 

[zz0468]

I've seen some low quality copper clad steel cable purchased from Radio Shack and other consumer outlets that has some WEIRD loss characteristics. The cable looked ok, but my best guess is that the copper plate on the center conductor was too thin. By weird, I'm talking about 20 db loss in 50' runs.

Rf flows on the outer surface of a conductor, so with good quality cable, it shouldn't matter. But I'm not convinced good quality cable is sold at many places. I know it's NOT at Radio Shack.

 

[gcgrotz]

I think, but I could be wrong, that RG6 and RG59 have copper/steel center conductors because the wire itself is the center pin and that stiffness is necessary for insertion into the jack. Solid copper is just too soft.

P.S. 20db loss in 50ft is not caused by thin copper plate, there was something else drastically wrong with that cable.

 

[zz0468]

P.S. 20db loss in 50ft is not caused by thin copper plate, there was something else drastically wrong with that cable.

I'd like to agree with you. I'm talking about brand new cable, and not just one piece. Good dc continuity, not crushed or damaged, no water damage. This is fresh off the shelf. Sweeping it, it had a steady increase in loss. It was useless above a few mhz. The only thing I could see was that the center conductor didn't look like shiney copper plate.

I'll never know for sure...

 

[prcguy]

Copper clad steel center conductor on RG6/RG-59 is purely a cost savings, the solid copper center cables are plenty stiff for use as the F connector center pin. If you can find a freq vs loss chart for steel RG-6 you can see an odd frequency response where the loss at 100KHz is worse than a few MHz and then it takes on the classic increasing loss at higher freqs. What freq did ZZ see the 20dB loss?
prcguy

I think, but I could be wrong, that RG6 and RG59 have copper/steel center conductors because the wire itself is the center pin and that stiffness is necessary for insertion into the jack. Solid copper is just too soft.

P.S. 20db loss in 50ft is not caused by thin copper plate, there was something else drastically wrong with that cable.

 

[gray1]

Well Im not real thrilled about the cable I bought anyway. I only have a 50 foot run. I think im going to order the solid copper center or the Commscope off E-bay. I think either would be a better choice that the Philips brand from Lowes. I can not find any spiecification on it at all. The only reason I bought it is that it had the compression fittings on it rather than the crimp type.

 

[prcguy]

Why not use RG-8, LMR-400 or other low loss 50ohm coax? It would cost less than $25 for 50ft of LMR-400 with PL-259s.
prcguy

 

[gray1]

Where would you suggest I get it? I cant seem to find anything local?

Thanks

 

[prcguy]

I have heard good things about this company: http://www.jefatech.com/product/ll400
It looks like 50ft of LMR-400 with N, PL-259 or BNC connectors installed is $44.95. Bulk LMR-400 is 43c/ft, not the cheapest but not a rip off either. If you were local (So. Cal.) I could probably set you up with some.
prcguy

Where would you suggest I get it? I cant seem to find anything local?

Thanks

 

[zz0468]

What freq did ZZ see the 20dB loss?
prcguy

That was at around 150 MHz.

I swept the cable from 0 to 1 GHz. It was just a steady increase of loss, but far steeper than anything I'd ever seen before.

 

[gcgrotz]

Well, that's all very interesting. If I ever get my sweep gear back from the tech that borrowed it last week I will have to try that. I must admit I've never actually swept TV type coax before. Since my gear is for 50 ohm I would expect to see some mismatch but 20db at 150 MHz?!

What are you using for sweep gear there zz? The steady rise in loss is to be expected but that seems steep. I used Lowe's bought Phillips brand, 50 ft with connectors, for my UHF TV antenna on the roof and I get a pretty excellent picture up to ch 41.

Now see, this is why we belong to RR, so we can learn stuff!

 

[zz0468]

It was quite interesting to see. Similar lengths of different brands of coax looked normal. It was just plain bad coax!

I use an HP 8722ES network analyzer above 50 MHz, and an HP 141T with a tracking generators below 50 MHz. BTW, I use broadband 50 to 75 ohm transmormers when sweeping 75 ohm devices.

When you're using high end equipment, it becomes VERY apparent just how crappy the consumer grade stuff is. The nice thing about the 8722 is that you can correct for any bumps in adapters or interconnect cables, so what's being measured is just the device (or cable) under test.