RG-6 versus RG-11

[LIScanner101]

The more I look into it, good quality RG-6 (not Home Depot or RS crap) is fine for short runs for scanning, such as for running from a window to your desk, or perhaps if you have a wall jack (LARGER main line coming down from attic or outside on chimney or tower) and you want to run it from the wall to somewhere in your den. It's thinner and more flexible and easier to work with.

Look at some figures I found poking around on loss charts on the web:

RG-6 – loss at 50MHz, 18’: 0.252dB
RG-11 – loss at 50MHz, 18’: 0.180dB

You would never notice the 0.072dB difference here.

Even at 400MHz:

RG-6 – loss at 400MHz, 18’: 0.774dB
RG-11 – loss at 400MHz, 18’: 0.630dB

Again, a difference of only 0.144dB. Who’s going to notice that?

And to think I got all worked up about this…

 

[GTR8000]

Ah, and now you are finally seeing the light! For short runs, especially jumpers between RG8/RG11 and the back of the scanner, you will never notice the extremely minimal loss. Remember, most loss figures are quoted for 100', so if you do the math you wind up with negligible numbers at much shorter lengths, as you've realized. The same is true for something like BNC vs TNC. At <1 GHz frequencies, you will never, ever notice a difference between the two.

By all means, get the best stuff you can afford, and install it correctly. There are always things you can and should do to improve the situation, but at a certain point you wind up over-thinking it. You wind up stressing out about fractions of dB's of loss that amount to nothing when you're talking about casual monitoring. I'm not being dismissive of it, everyone wants to pull in every signal possible, but you've got to be realistic. Stressing out about coax loss figures to the 100th decimal place for a receive-only hobby setup is crazy.

In the end, you've got to be realistic and stop over-engineering things.

 

[mmckenna]

Bingo. Some people get really hung up on things like connector loss, cable loss, and the like. If you loss budget is so tight that you can't deal with a fraction of a dB, then you are doing something wrong, or expecting more from your system than it is reliably capable of.
It's good to use the best you can afford, but being reasonable is a good option also. I've seen people arguing about what the best coax is and how others should spend more on it, but all they see is that tenth of a decibel and think it's going to make or break a system.

 

[LIScanner101]

Ah, and now you are finally seeing the light! For short runs, especially jumpers between RG8/RG11 and the back of the scanner, you will never notice the extremely minimal loss. Remember, most loss figures are quoted for 100', so if you do the math you wind up with negligible numbers at much shorter lengths, as you've realized. The same is true for something like BNC vs TNC. At <1 GHz frequencies, you will never, ever notice a difference between the two.

By all means, get the best stuff you can afford, and install it correctly. There are always things you can and should do to improve the situation, but at a certain point you wind up over-thinking it. You wind up stressing out about fractions of dB's of loss that amount to nothing when you're talking about casual monitoring. I'm not being dismissive of it, everyone wants to pull in every signal possible, but you've got to be realistic. Stressing out about coax loss figures to the 100th decimal place for a receive-only hobby setup is crazy.

In the end, you've got to be realistic and stop over-engineering things.

That's my biggest problem, right there

I worry about tenths of a dB while at the same time talking about mounting an antenna in an attic...!

I need to really lay back a bit!

Thank you!!

 

[LIScanner101]

Bingo. Some people get really hung up on things like connector loss, cable loss, and the like. If you loss budget is so tight that you can't deal with a fraction of a dB, then you are doing something wrong, or expecting more from your system than it is reliably capable of.
It's good to use the best you can afford, but being reasonable is a good option also. I've seen people arguing about what the best coax is and how others should spend more on it, but all they see is that tenth of a decibel and think it's going to make or break a system.

Again, that’s me right there. I need to stop fretting over things like worrying whether a total calculated signal loss of, say, 1.75dB is “worse” than 1.5dB. I see now that’s a fool’s folly and it’s not going to make a damned bit of difference for general scanning.

Thank you too for opening up my eyes!

 

[GTR8000]

I worry about tenths of a dB while at the same time talking about mounting an antenna in an attic...!

True, however you do have the right frame of mind overall. Anything worth doing is worth doing right, and worth doing right the first time! Yes, you are definitely handicapped from the get-go by having the antenna in the attic, however that doesn't mean you should just throw in the towel and run 100' of pathetic RG58 from Radio Shack.

By all means, get the best coax you can afford and do it right with the connectors, keeping adapters to a minimum. For receive-only applications, going with good quality RG11 and F compression connectors will work fine, you don't need to go with RG8 and N connectors (unless you want to future proof your coax, anticipating eventually switching to an antenna that will have an N connector).

RG11 is cheap enough compared to RG8 that even if you decide to upgrade in the future, you're not breaking the bank. I can get high quality Belden RG11 for 24 cents a foot, versus 79 cents a foot for LMR-400, and the loss numbers are identical at 900 MHz/100' (-3.9 dB). That's 1/3 the price for the same performance, and in your case where the antenna already has an F-female, it's kind of a no-brainer to stick with 75 ohm cable and native F connectors. Anyone who argues that there is any difference between 50 ohms and 75 ohms for receive-only applications on a consumer grade wideband scanner is just talking to hear themselves talk. There is absolutely no practical real world difference.

 

[mpddigital]

RG-11 will work well for scanning under the 900 MHz range. If you are going up into microwave freqs I still think good 50 Ohm coax is better.

 

[LIScanner101]

RG-11 will work well for scanning under the 900 MHz range. If you are going up into microwave freqs I still think good 50 Ohm coax is better.

Hello,

Please check your PMs.

Thanks
John

 

[WayneH]

Only authorized representatives may offer their services and they will never offer them privately"

LIScanner101, please see what I quoted above. MPPDigital is allowed to advertise in his signature. If a member so chooses to contact them (generally speaking, anyone authorized) they're on their own though. If someone who is authorized conducts confirmed bad business then their authorization is voided.

Also, please get familiar with the Forum staff so next time you see our name you will not confuse us. My name shows up when I edit a post.

From my post on, everyone please stick to the thread topic. Anything off topic needs to go private.

 

[LIScanner101]

Wayne,

Sorry, I think you're making a mountain out of an anthill. The least mp could have done was reply to my PMs and simply say "I'm sorry but I am not authorized to talk about this matter over PMs". That would have been it. Just ignoring me 3x doesn't seem like it's good for his business. But no worries, you can rest assured that I will NEVER contact him again on this site OR on his storefront. End of story. I'm done with this thread.