Coaxial Cable

[CSL126]

Hey guys, is LMR-400 a good choice of coax for UHF and 800 MHz? I'm using RG-6 right now, would that cable really make a noticable difference?

 

[scannerfreak]

100% without a doubt you would see a HUGE difference going from 6 to LMR 400..Here is a good tool for figuring out what you'll gain:

http://www.timesmicrowave.com/cgi-bin/calculate.pl


PS- I have bought many runs of LMR from this place. This is about as cheap as it gets when it comes to LMR-400

 

[kingpin]

I use LMR-400 for more than half on my antennas and I've never looked back. EXCELLENT stuff. It's a bit pricey but worth it for the higher bands and it's worth the investment.

 

[N_Jay]

How many feet?

Figure the losses and then decide.

On short runs you may not notice the difference.:wink:


I love people who make absolute statements without enough facts!:roll: :evil:

e.g.
"100% without a doubt you would see a HUGE difference going from 6 to LMR 400"

 

[CSL126]

It's a 50 ft run, but i may decide to add about another 25 ft.

 

[N_Jay]

It's a 50 ft run, but i may decide to add about another 25 ft.

http://www.timesmicrowave.com/cgi-bin/calculate.pl
(Nice link, thanks)

At 900 MHz

75' LMR-400 2.9 dB, RG-6 6.6 dB

3.7 dB is a marginal difference, probably only worth it IF you have signals that today are a bit noisy and you want better.
If you don't hear it now, 3.7 dB is not going to "bring it in"!

At 50 feet it is 2.0 dB vs. 4.4 dB

2.4 dB is hardly worth worrying about on a receive system.

LMR-400 will last longer than RG-6 in the weather.

LMR-400 will probably need an adapter and jumper on the radio end adding an extra 0.5 to 1.0 dB of loss not included in the above.

 

[scannerfreak]

How many feet?

Figure the losses and then decide.

On short runs you may not notice the difference.:wink:


I love people who make absolute statements without enough facts!:roll: :evil:

e.g.
"100% without a doubt you would see a HUGE difference going from 6 to LMR 400"

:lol: :lol::lol: :lol: :lol: Which is why I provided the calculator:roll: I don't care if it's 5'..He would benefit switching cables..RG-6 is crap, especially on 800...2.4 DB not enough to worry about? You're carzy...Try changing cables and let us know how much more you hear..That's the test..We can look at numbres all day long, but if it ends up pulling in stuff you couldn't hear before, well then you gained My N to BNC adapter has .02 db of loss..Now that''s not enough to worry about..

 

[N_Jay]

:lol: :lol::lol: :lol: :lol: Which is why I provided the calculator:roll: I dont' care if it's 5'..He would benefit stiching cables..2.4 DB not enough to worry about? You're carzy...

I'm crazy? (Well maybe so)

But that aside;

adding 2.4 dB to a signal you are not getting will leave you with a signal you still don't get good enough to listen to.

adding 2.4 dB to a signal that is real noisy will leave you with a signal that is still fairly noisy.

adding 2.4 dB to a signal that has just a little noise will leave you with a signal that has just a little less noise.


And at 5 feet, your connector losses for either cable outweigh the loss of the cable, so I think you can join me in being crazy (heck, you might even be more crazy)

 

[N_Jay]

Looks like we were editing at the same time.

And just how did you MEASURE your adapter???

 

[RISC777]

http://www.timesmicrowave.com/cgi-bin/calculate.pl
(Nice link, thanks)

Agreed, good link. (I keep 'misplacing' it...lol)

LMR-400 will probably need an adapter and jumper on the radio end adding an extra 0.5 to 1.0 dB of loss not included in the above.

If CSL126, or anyone, orders it 'pre-terminated' you don't always have to use adapters if you tell the place you're getting it from what you want at each end.

 

[scannerfreak]

I'm crazy? (Well maybe so)

But that aside;

adding 2.4 dB to a signal you are not getting will leave you with a signal you still don't get good enough to listen to.

adding 2.4 dB to a signal that is real noisy will leave you with a signal that is still fairly noisy.

adding 2.4 dB to a signal that has just a little noise will leave you with a signal that has just a little less noise.


And at 5 feet, your connector losses for either cable outweigh the loss of the cable, so I think you can join me in being crazy (heck, you might even be more crazy)

The 5' reference was to him benefiting even if it is only 5', which, he will benefit by having a much better cable..My adapter specs were the manafactures tech specs which came with the adapter. I'm not going to argue the reception issue. I know what going from RG-6 to LMR-400 does at 50', so I am positive what it will do at 75 or 100'

 

[N_Jay]

If CSL126, or anyone, orders it 'pre-terminated' you don't always have to use adapters if you tell the place you're getting it from what you want at each end.

I was referring to the fact that LMR-400 is usually a bit stiff to get to bend to where you want it.

If you can, then no jumper is best.

 

[N_Jay]

The 5' reference was to him benefiting even if it is only 5', which, he will benefit by having a much better cable..My adapter specs were the manafactures tech specs which came with the adapter. I'm not going to argue the reception issue. I know what going from RG-6 to LMR-400 does at 50', so I am positive what it will do at 75 or 100'

I don't know what the loss was on your "OLD" RG-6 was before you put on your "NEW" LMR-400.
(This is a common problem with anecdotal information, you only get 1/2 the story, and usually less than 1/2 the facts)

The 5' reference was an indication to me that you were being irrational in your answer.
Why would anyone want to swap out 5' of RG-6 for 5' of LMR-400 on a scanner?

No one has even asked what type of antenna he has?

Maybe the $50 would be better put into a better antenna, or maybe put into a taller mount (if local obstructions are the issue).

Sorry to be such a pain, but your "blanket" recommendations just don't "cover" everyone.

 

[scannerfreak]

I don't know what the loss was on your "OLD" RG-6 was before you put on your "NEW" LMR-400.
(This is a common problem with anecdotal information, you only get 1/2 the story, and usually less than 1/2 the facts)

:lol:

The 5' reference was an indication to me that you were being irrational in your answer.
Why would anyone want to swap out 5' of RG-6 for 5' of LMR-400 on a scanner?

Not 5' of cable total, 5' addition is what I was talking about

No one has even asked what type of antenna he has?
a taller mount (if local obstructions are the issue).

Does it matter? Without the right cable what good is your antenna...

Sorry to be such a pain, but your "blanket" recommendations just don't "cover" everyone.

Yes they do, I don't care what the situation is, LMR-400 is much better cable in more ways than just signal loss..

 

[mastr]

Another factor is the myriad of so-called "RG6" cables in use. "RG6" has become a catch all nomenclature for any 75 ohm cable of about .270 inch diameter. The quality varies greatly depending on the maker and intended application, while "LMR400" refers to a specific brand and type.

I have seen some brands/types of RG6 cable perform quite well and last 20 years or longer, while some are nearly useless right off the spool. Belden, Commscope or Times all make decent RG6 cable if you shop around for the right variation. If LMR400 was "always" better, the production of RG6 would almost certainly stop right away; I don't believe that is going to happen any time soon. There are some instances where a 75 ohm cable is preferable, and many where the impedance simply doesn't matter enough to be an issue. The price of RG6 can be really good if you are on friendly terms with your local CATV installer.

Improper weatherproofing at terminations can make even the best cable fail prematurely, it takes more than a wrap or two of electrical tape and a dab of silicone to do the job.

W

 

[N_Jay]

The 5' reference was an indication to me that you were being irrational in your answer.
Why would anyone want to swap out 5' of RG-6 for 5' of LMR-400 on a scanner?

Not 5' of cable total, 5' addition is what I was talking about

Well OK, but I don't quite get where the 5' is extra or whole length. (maybe what your wrote is different than what you meant? We have all done that)

No one has even asked what type of antenna he has?
a taller mount (if local obstructions are the issue).

Does it matter? Without the right cable what good is your antenna...

Well, it does matter because the opposite is also true, with a bad antenna, the cable is irrelevant.

So the real issue is given a certain expense, what is the best way to improve the system.

Sorry to be such a pain, but your "blanket" recommendations just don't "cover" everyone.

Yes they do, I don't care what the situation is, LMR-400 is much better cable in more ways than just signal loss..

Yes, and true, but "better" in general does not make something "better" for the particular situation.

It is important to understand that that "good enough", is "GOOD ENOUGH", and that "better" is only "BETTER" when it makes a noticeable difference.

Using your logic we should all be using 1 5/8 air line! (or better):roll: :lol: :lol: :lol:

 

[RISC777]

Originally Posted by RISC777
If CSL126, or anyone, orders it 'pre-terminated' you don't always have to use adapters if you tell the place you're getting it from what you want at each end.

I was referring to the fact that LMR-400 is usually a bit stiff to get to bend to where you want it.

If you can, then no jumper is best.

Very true, if you bend it, it definitely wants to stay where you "left it." That can be a good or bad thing sometimes. Besides the fact it's 3/8" (which so is the 9913).

Now that UltraFlex with the stranded core, that stuff is way cool to work with. Though I once almost bought a run of the flame retardant just to have the outer orange sheath. :lol:

[ off-topc: N_Jay, you ever worked with any -600? ]

 

[N_Jay]

Another factor is the myriad of so-called "RG6" cables in use. "RG6" has become a catch all nomenclature for any 75 ohm cable of about .270 inch diameter.

Just to clarify, "RG" numbers have ALWAYS been a general type specification and have NEVER indicated a specific quallity level.

 

[N_Jay]

Originally Posted by RISC777
If CSL126, or anyone, orders it 'pre-terminated' you don't always have to use adapters if you tell the place you're getting it from what you want at each end.

Very true, if you bend it, it definitely wants to stay where you "left it." That can be a good or bad thing sometimes. Besides the fact it's 3/8" (which so is the 9913).

Now that UltraFlex with the stranded core, that stuff is way cool to work with. Though I once almost bought a run of the flame retardant just to have the outer orange sheath. :lol:

[ off-topic: N_Jay, you ever worked with any -600? ]

You mean LMR-600?

I have seen installations with it, but I'm "Old School" and still prefer specifying corrugated copper shielded cable (Andrew type).

Sort of Off-Topic:
Some people mistakenly believe that the flexible solid shielding type cables (The flexible version of LMR-xxx and the Super-Flex versions of LDF-XXX) are suitable for use a "flexible cable", to be bent and re-bent many times.

This is NOT true. The cable is more flexible and has a tighter bending radius for ease of installation, but is NOT meant to be flexed multiple time and will fail if used that way.

 

[mastr]

"RG" types were listed in a government document- MIL-HDBK-216, dated 4 January 1962. This document specified outer jacket and conductor diameters, impedance and in some cases dielectric type. As N_Jay pointed out it contained no quality control standards other than those mentioned. MIL-HDBK-216 was "cancelled without replacement" effective Sept 6, 2001, effectively allowing manufacturers to legally stamp "rg6" on any size cable they care to.

Long before then, the "rg6" nomenclature was placed on .270 inch cable that more closely resembled rg59, by some of the more creative vendors, since the cable could be sold for a higher price by virtue of having that designator. Some of it was literally not worth taking off the reel. An accurately lableled rg6 cable is close to .332 inch diameter, and rg59 is .242 inch.

W