Best Coax?

[Robb]

not to argue , but an honest question . wouldnt the skin effect be negated by the surface area of the center pl259 connector ? seems the copper stranded center may allow for more surface area but it cant add more than what is passed by the 259 . or can it ? im not even taking into effect the lil wire from the amps board to the center of the so239 .

I'd agree to that. EXCEPT that the l o n g coax isn't allowed to be the 'weak link' in the chain from your radio to the antenna/load when superior cable is used. Between those two spaces, one needs to get everything there that came out of the SO-239 connector that is available from your tweaked/peaked gem of a radio you have. Why do you like LMR 400? Because it is made of such high quality material and engineering to ensure that your signal remains intact/unmolested. The 'skin effect' is still a fact of physics, as you know all too well what would happen if you hooked up your Maco V-5000 to your Texas Ranger with a cheap 100 ft piece of RG-58! Betweem the poor shielding, high-oxygen content copper of a thin guage center core RG-58, you would lose almost 50% of available power from your radio to the antenna! A loss of just one db on 100 ft run can reduce power output by 20%. Cable quality is generklly more critical for 6m, 2m, and 449Mhz than 11m; but it is still a big differnece at that length! That was one of the questions on my General test that I took yesterday - BTW! And yes; I passed!

 

[Master Chief]

The more surface area that exists on a wire ('multi-core vs solid core'), it is better against resistance to flow. It is called the 'skin effect'; as there is more surface area on a stranded wire than a single solid oned.

Ah, no. A solid core wire has more surface area. Go back and look at it.

There is a reason why the specs are better for the solid core LMR-400 than the stranded core LMR-400 Flex.

Heliax, LMR-400, 9913, all use solid cores. There is a reason!

 

[74IN]

Surface area conducts RF.

The greater surface area, the more area rf will have to travel on.

 

[74IN]

But at HF frequencies, it's moot.

 

[Master Chief]

Surface area conducts RF.

Nope. Surface are is......surface area. The WIRE conducts the RF.

Coax is not moot at HF frequencies. While the losses may be, the coax is most certainly not!

 

[74IN]

Coax is not moot at HF frequencies. While the losses may be, the coax is most certainly not!

Please expand on that.

Loss from 8x to LMR 400 is not noticeable.

The charts that the manufactures show it.

Am I missing something? Quality?

Please inform me.

 

[Lazybones1222]

Uh....the best coax is not coax. It's ladderline. Ahem

 

[74IN]

Give it a try on UHF.

 

[KingCobra_CDX882]

Yes Money is well spent on Good Coax-Feedline.

But while i use Andrews Heliax LDF5-50a most say it is over kill.
Yet at the same time many ask how i am able to get out as i do and still have no amp or RF interference issues with neighbors.

It all goes back to the coax (typically the wink link in most peoples set ups
Myself i am running 155 to 165 ft to my Interceptor I-10K.

You can keep your RG8 or RG213 and even LMR400.

It is the antenna system that is the most Important in your set up and guess what people,coax is part of the antenna system.

Now only thing better in many respects to my hardline i use is the ladderline (but that would not work well for me..is too bad i would have prefered using ladderline indeed)

Oh and to close my Andrews Heliax LDF5-50A has been up a few years without the slightest issues (and will remain issue free i am sure for years to come .. due in part in that going to the antenna i am using N connector which is better at keeping the water out over extended time )

 

[W5LZ]

Skin effect.
Just means how 'deep' into a conductor RF penetrates. More surface area means less depth, which also means less resistance, or impedance since it's AC. While skin effect does have some affect, does have it's uses, it just isn't that much of a factor in it's 'worth' when dealing with feed lines. Not worth spending too much worry on, all things considered. Other characteristics commonly play a much greater part in that 'worth' thingy.
- 'Doc

 

[Captain Kilowatt]

Ah, no. A solid core wire has more surface area. Go back and look at it.

There is a reason why the specs are better for the solid core LMR-400 than the stranded core LMR-400 Flex.

Heliax, LMR-400, 9913, all use solid cores. There is a reason!

Soory,I disagree. the quality and losses associated with coax cable depend on more than the size of the centre conductor and whether it is solid or stranded. Stranded wire WILL carry more RF current for it's size and have less resistance than solid wire of the same size.The reason is surface area and the surface area of all the individual strands in stranded wire total more than the surface area of a single large strand.The very large feedlenes like heliax and hardline have hollow centre conductors like a piece of copper pipe which allows a MUCH greater surface area as both the inner and outter surfaces of the same conductor come into play.

 

[Master Chief]

The losses are dependent on the insulator material used between the center conductor and the outer shield. The impeadance is dependent on the distance between the two conductors and the insulating material.

As far as the solid vs stranded comments go.....

Since RF flows on the surface of a conductor (we can at least agree on that) whether heliax or any other conductor is solid or hollow is a non-issue.

Two wire diameters, one solid and one stranded, of the same diameter (.405") will always show the solid conductor of having more surface area.

Everything I said the first time was correct.

 

[W5LZ]

Which has the most surface area, A wire shaped like this '*' with a diameter of .405", or one shaped like this 'o' with a diameter of .405"?

...sorry, that's as close as I can get with the character's on my keyboard.

 

[74IN]

Two wire diameters, one solid and one stranded, of the same diameter (.405") will always show the solid conductor of having more surface area.

I say bunk.

An irregular surface creates more surface area.

 

[74IN]

You beat me, Doc.

Was posting at the same time, I gotta type faster.