LMR 400 vs standard RG8X

[Alabama Buckeye]

Velocity Factor would be my 1st reason for choosing LMR coax. I've no idea of the bearing VF would truly have upon short lengths, <100'; more often < 50'.
My RX signal wont be improved with LMR, filtering out the foul mouths; and, TX to Australia and N. Ireland from C. AL is good enough for me with RG8X.
Longevity would be the 2nd reason; though I've no confirmation data to base this reasoning on.

Really? Velocity Factor has some impact of importance on HF radio signals?

 

[Dr_DX]

Just want to point out a few facts.

Using the 2 screenshots of TLD that Mike provided.

Using 75' of RG8x, you will lose 23.4% of your power before it even gets to the antenna. Using LMR400, you will lose 10.6%. That is 12.8% more power to the antenna using LMR400.

Conversely, you will lose 23.4% of your receive signal using RG8x. You will lose 10.6% of your receive signal with LMR400. You will receive a 12.8% stronger signal with LMR400.

For any signal that is over 1 S unit on your receiver or their receiver, it won't matter; you will still be able to have a QSO.

For any signal that is an "audio" only copy, or just wiggles the needle, it makes all the difference in the world. You won't hear them and they won't hear you with RG8x.

I can promise you that you will hear more stations and more stations will hear you if you use LMR400. No one else here will promise you the opposite; that you can hear more stations and more stations can hear you with RG8x.

Basically, 1/10th loss vs. 1/4 loss.

The question you have to ask your self, is that worth $50? Only you can answer that.

Good Luck and welcome to the forum.

 

[sp5it]

Conversely, you will lose 23.4% of your receive signal using RG8x. You will lose 10.6% of your receive signal with LMR400. You will receive a 12.8% stronger signal with LMR400.

How it translate to the real world results?
RG8X loss is 1.1 dB which makes 0.11 S unit less on TX and RX
LMR loss is 0.489dB which makes 0.0489 S unit less on TX and RX

It's not something you can see or hear on 27MHz.
Just laws of physics.
Mike

 

[whiteastro]

8x is fine.
View attachment 60984
View attachment 60983

Thanks for the charts ! Not being a professional radio person I expanded & printed each and will have to study them to see if it will sink in to my thick skull. LOL

 

[Dr_DX]

How it translate to the real world results?
RG8X loss is 1.1 dB which makes 0.11 S unit less on TX and RX
LMR loss is 0.489dB which makes 0.0489 S unit less on TX and RX

It's not something you can see or hear on 27MHz.
Just laws of physics.
Mike

1.16 - .489 = .671dB difference

I don't know about you, but I can hear the difference when I am getting an "audio only" copy with LMR400. Swap it out with RG8x and it disappears into the noise floor. That's when it makes a difference.

Real World.

Just law of physics...

 

[whiteastro]

I know I've had bad ears all my life so I need all the help I can get. Up steps the VA with 2 nice Hearing aids so I guess there is some benefits to being a VietNam Vet !

 

[sp5it]

I know folks who hear difference in power cables going to their equipment.
EOT for me.

 

[Beetle]

Mike, you are the Master, master of electronics, theory, cb's etc... I don't understand what you just wrote whatsoever . lol ,tho I did understand and was able to Cipher the graphs you sent nicely THANKYOU FOR THAT., just getting back into cb's after 45 years, My wife is the one who suggested getting back into CB's. Her family owned trucking company she grew up rag chewing in her teens. My dad had cbs coming out his... She even got our son one for his truck...As an adults, now we can buy cool stuff a 13yr old couldn't! hahahaha. Built our sloper,well I made her do the work,she became a proficient solder-er and crimper. After tens of dollars of practice materials. She asked about cleaning up old solder and re-soldering ,so I explained indepth how the old Solder Suckered worked ... Oh my god ! My mistake , she HAD to have one. So needless to say , she got her Solder Sucker and learned to use it ! Hahahaha true story! Thanks again Bro. U been a Ton-0-help . "Rick944 from so. Nevada." "LadyDi69 from so. Nevada." listen for us on the skip in the am. ch 23,28,

Hey! I could have been "Pat from So. Nevada"! Lived the first 20 years of my life in Vegas. Original house is still there exactly one block East of Pawn Stars, which was a photography/camera shop when I was a lad!

 

[Alabama Buckeye]

sp5it said, "It's not something you can see or hear on 27MHz.
Just laws of physics.
Mike"

Dr DX said, "Using 75' of RG8x, you will lose 23.4% of your power before it even gets to the antenna. Using LMR400, you will lose 10.6%. That is 12.8% more power to the antenna using LMR400."

Then while I stumble through the graphics and see 100W reduced to 77W with 8X but only a reduction to 89W with LMR400.

What appears alarming at first impression is Electrical Length Modulo...1/2 WL ?

Thanks Mike for making the graphs available.

 

[Captain Kilowatt]

1.16 - .489 = .671dB difference

I don't know about you, but I can hear the difference when I am getting an "audio only" copy with LMR400. Swap it out with RG8x and it disappears into the noise floor. That's when it makes a difference.

Real World.

Just law of physics...

Then you better pat yourself on the back and be glad that you are a member of an elite group of radio operators because the other 99.9% of us will see no discernible difference. The minimum discernible difference in audio is considered to be 1 Db. Again, congratulations on being part of the elite.

 

[Captain Kilowatt]

In addition to the above, I would suggest that the RG-8X actually has more losses than spec. Which would certainly account for the difference. This is not uncommon and many have thought the coax itself was much better when in fact the other cable had issues despite showing a good SWR. I myself was fooled by that MANY years ago.

 

[Dr_DX]

Then you better pat yourself on the back and be glad that you are a member of an elite group of radio operators because the other 99.9% of us will see no discernible difference. The minimum discernible difference in audio is considered to be 1 Db. Again, congratulations on being part of the elite.

Thanks for the compliment, I appreciate it! Other people have remarked about my exceptional hearing too.

 

[Captain Kilowatt]

Thanks for the compliment, I appreciate it! Other people have remarked about my exceptional hearing too.

I bet you can even hear the difference in audio if the source uses gold plated AC plugs instead of brass ones too.
Just don't pull a muscle patting yourself on the back too hard.

 

[Dr_DX]

I bet you can even hear the difference in audio if the source uses gold plated AC plugs instead of brass ones too.
Just don't pull a muscle patting yourself on the back too hard.

You'd lose that bet.

But hearing a signal right above my noise floor as opposed to one down in the noise floor, you betcha. Every day, all day, and twice on Sunday...

 

[Newbie solar guy]

I've got a new 100 foot length of Times Microwave LMR400 with some very nice connectors sitting next to me that I've been meaning to replace. It wasn't that expensive, about a dollar a foot when I bought it. Maybe it's gone up now like everything else.

How bouts yous send et ova... I could use a peice-a like-a dat-a, capiche? Was ya lookin to off it? 73 to the Family.