Cable

[LukeB]

What is the best cable available for a non-professional system with a run of about 65'-80'?

I recently had an antenna cable of mine cut and wound up re-routing antenna's to scanners. I find that after I have re-routed, I have experienced a slight improvement with my reception. The cable that was cut was the supplied cable that comes with the Scan-tenna.

I've made the assumption that it may be my cable causing the problem. I thought I had some decent stuff (LMR-400, Belden) but I may need something more substantial, hence I pose the question.

 

[fineshot1]

What is the best cable available for a non-professional system with a run of about 65'-80'?

I recently had an antenna cable of mine cut and wound up re-routing antenna's to scanners. I find that after I have re-routed, I have experienced a slight improvement with my reception. The cable that was cut was the supplied cable that comes with the Scan-tenna.

I've made the assumption that it may be my cable causing the problem. I thought I had some decent stuff (LMR-400, Belden) but I may need something more substantial, hence I pose the question.

Something is not quite right with the details in your post - Belden does not make LMR 400.
Times Microwave makes LMR 400 cable and there are some other clone makers of the 400 style cable.
I was going to suggest LMR 400 or 600 cable and using Belden 8240 for any jumpers needed.

 

[LukeB]

Sorry for the confusion. I have 2 separate types of cable. 1 is LMR-400 and the other is Belden 9914 I believe. Both are running to 2 separate antenna's.

Evidently my problem is the distance of the run. I have no way of shortening it up unfortunately. I would gather that I am losing the signal in the lengthy run.

I know people use towers and run far longer cable then I am running so I guess my question is what type of cable are you running for these applications? I monitor all across the board (from low band to 800mhz) using scanners. I am getting UHF radio and pairing it with a strictly UHF antenna to see how that works. If successful, I suppose I will get a low band, VHF and 800mhz radio to pair and look into setting up 3 single band antenna's for each.

I will still need to get around the scanner issues and loss of signal. Hope this gives a little more insight into what I am looking to do and clears any of the confusion.

 

[fineshot1]

OK - thanks for the clarification. If you already have LMR400 that would be what I would recommend unless you want to get into the cable types that are much more difficult to work with such as LMR600 or half inch hard line. Can I assume you installed the connectors on the LMR400 and 9913 that you already have or were they installed already when you purchased? If they were improperly installed that could help to explain your rx signal problem. Just a thought.....

 

[N1BHH]

Actually, the best feed line for any antenna is heliax, in my opinion. Actually, the radio at the antenna is the ultimate, but that isn't practical. Using LMR400 is a very good example of a relatively high quality alternative (saves your money compared to heliax) as it is readily available at Ham Radio Outlet and many other ham stores. Some can be bought with connectors. As with all outside connections, plenty of goop at all connections will keep the drips out.

 

[kb2vxa]

Generally speaking coax has two major drawbacks, loss goes up with length AND frequency. At 800MHz LMR 400 gets pretty useless as the length approaches 100' so I would compare specs and prices looking for something that is a good compromise between efficiency and price. One other thing worth mentioning is the Scantenna as are many other common scanner antennas is a NO GAIN antenna. Obviously that means no matter what you're always operating at a signal deficit so you NEED to keep loss to an absolute minimum. Now if you feed the system with a high gain collinear you can afford some additional loss but still it pays to keep it to a minimum.

Last but not least pay little attention to advertising hype and that includes the "I use so and so and it works fine for me" stuff you read here. Be your own person and do your own homework, use what is best for your application which BTW may not work so well for the other guy when you sing the praises of YOUR installation. Funny ol' world now iddnit?

 

[ridgescan]

previous post deleted. WTF was I thinking????!!!

 

[LukeB]

Well put clyde and warren. Thanks for the advice. I happen to be a strong believer in that all applications are different, regardless of how successful our two similar set ups are.

I thought I was good with the LMR-400. I was told it was good cable, especially for longer runs. I seem to be missing a lot though, which has me concerned. I am not a pro by any means and don't know how to determine where the problem is. Which leads me to my next comment....

One other thing I left out of the entire mix is that I am in between 2 hills. I know I am limited to an extent but what makes me believe that this may not be the problem is after switching the antenna's around, I was able to hear better. I am sure I won't have amazing reception due to the terrain but I would think that it could be somewhere in the cables.

I am not overly concerned about the 800mhz system as I am in the heart of it. I hear it fine when all pistons are firing but after the switch, this is one area where my reception went down. It could be the antenna attached to that radio but a further investigation is needed.

Basically, I am looking to get my set up more serious and I know cable is often neglected. I have started with the crap and have seen where it has got me and moved up to what I thought was better. So now, I am still blaming the cable...

Thanks again for the advice gang!

 

[blueangel-eric]

Well put clyde and warren. Thanks for the advice. I happen to be a strong believer in that all applications are different, regardless of how successful our two similar set ups are.

I thought I was good with the LMR-400. I was told it was good cable, especially for longer runs. I seem to be missing a lot though, which has me concerned. I am not a pro by any means and don't know how to determine where the problem is. Which leads me to my next comment....

One other thing I left out of the entire mix is that I am in between 2 hills. I know I am limited to an extent but what makes me believe that this may not be the problem is after switching the antenna's around, I was able to hear better. I am sure I won't have amazing reception due to the terrain but I would think that it could be somewhere in the cables.

I am not overly concerned about the 800mhz system as I am in the heart of it. I hear it fine when all pistons are firing but after the switch, this is one area where my reception went down. It could be the antenna attached to that radio but a further investigation is needed.

Basically, I am looking to get my set up more serious and I know cable is often neglected. I have started with the crap and have seen where it has got me and moved up to what I thought was better. So now, I am still blaming the cable...

Thanks again for the advice gang!

wait a second you mean better cable gives worse performance? maybe it's the other way around and your scanner is desensing from stronger signals. in other words the LMR400 works better but now your scanner is overloading from strong signals and actually is recieving less/worse then before.

 

[zz0468]

LukeB, You've mentioned a "problem" several times in this thread, but you haven't really clearly defined at beyond a vague malaise that you're not receiving as well as you should, and you blame the coax.There could well be more to the problem, and ,maybe even no problem at all. Even comparing reception between two different antennas is meaningless unless there are some details given.

LMR400 has about 3.8 db loss at 870 MHz for 100' of cable. That's not a hugely significant amount of loss that would leap out at you. Your 80' run has 3.1 db loss. That's close the the threshold of what you;d notice on an FM receiver like a scanner. There could be poorly installed connectors, or maybe the cable wasn't properly weatherproofed. Either of those could toss the loss specifications out the window.

But maybe if you more clearly defined just what it is about your installation that makes you think it's not working we could do a better job pointing you in the right direction. right now, I'd be more inclined to blame those hills than anything else.

 

[poltergeisty]

http://www.ocarc.ca/coax.htm

Just might help..

How do you figure load SWR when you don't know what the SWR may be? I guess the antenna would say?

This here too. http://www.terabeam.com/support/calculations/watts-dbm.php#calc

 

[N_Jay]

http://www.ocarc.ca/coax.htm

Just might help..

How do you figure load SWR when you don't know what the SWR may be? I guess the antenna would say?

Don't worry about the SWR on a RX only system.

 

[hoser147]

Lots of factors to consider when it comes to antennae, zz o468 may be right and it could very well be the terrain or as mentioned before the connectors or not sealed up properly. If you have the Lmr 400 give it a try what are you out. Just pay attention to all the little things. Hoser

 

[Lowa2]

Don't worry about the SWR on a RX only system.

I hate that quote.

It just doesn't make sense. I mean i know it won't damage the radio, but it will hurt reception. We had a VHF air antenna on a "rx only system" with a swr of 3:1, and it brought range down from about 200 miles, to 30 miles.

Replaced it, and got more than the required 200...

End rant.

Check your connectors for water, and seal them up well!

 

[LukeB]

I had a whole message typed but lost it and I am not in the mood to re-type it. How do you suggest water-proofing and sealing the connectors?

In the end, I am just looking to see what people are using for their long runs of cable. I am not equipped or knowledgeable enough to diagnose the problem. I do not have any meters or such nor would I know what I was looking at. I appreciate the advice but I do not know exactly how to use it.

Sorry this post turned into a cluster.

 

[Lowa2]

go to your local electrical supply store, and get an underground splice kit. It's basicallly a 3/4 in heat shrink about 1 foot long with glue on the inside. Put the heatshrink on the cable, then connect your cable to your antenna. get yourself a good heat gun, and shink the shrink wrap until the glue oozes out of both ends of the wrap (this will take about 5 minutes)

As for cable, as most say, LMR400 would be fine, as would LDF4-50, or any commercial cable that's 3/8 to 1/2 inch, but it all depends how much you want to spend. The most bang for the buck would be LMR400.

Good luck!

 

[poltergeisty]

Don't worry about the SWR on a RX only system.

Kinda figured, but according to Lowa2... maybe not. :lol:

Back to the original topic. The connectors have got to be your biggest issue. As mentioned, check them. You do run a continuity check after right?

 

[LukeB]

Negative on the continuity check. How is it done and what am I looking for?

Please excuse my ignorance.

 

[kb2vxa]

"Your 80' run has 3.1 db loss. That's close the the threshold of what you;d notice on an FM receiver like a scanner."

I strongly disagree, back to my post that was very well understood. One must consider S/N ratio commonly known as "quieting" when it comes to FM signals. Without an uber geek explanation this may seem a bit vague but what it comes down to is 3dB is either twice or half the signal depending on which side of zero you're standing on. Simply stated when signals are strong you'll never hear the difference but with less than optimum levels noise becomes a factor and intelligibility becomes an issue. Just because a signal is present doesn't say you can extract usable intelligence from it so the rule of thumb is the larger the diameter pipe the more water you'll get.

Somebody please pray for my horse, I think he's dead. (;->)

Now I just can't resist this one;
"Powder to the People"

 

[LukeB]

Wrong powder but cute joke....