Maximum Coax Length?

[Grandpap]

Hi all, I am in the process of setting up my shack and I appreciate all that I have learned from reading the old posts here. I have a Uniden Washington base station, and I plan on running am/ssb for a while just because a lot of locals utilize these frequencies.
I have not decided on an antenna yet, but about the only place I have to set up my tower gives me a run of about 160 feet from my shack (top of tower to back of the radio).
I would have to put my antenna on the back side of my garage, and the coax would have to be run down the tower (30 feet), through the attic of the garage (60 feet), through the air to the house (25 feet), through the house attic, and finally down into the to the "shack" (40 feet).
Now, having said all that, If I use LMR-400, is this too much? What is the maximum run of coax I can use without getting into loss, r.f. interference,coax deterioration problems etc.?

 

[Justme]

160 feet will be about 1.2 dB loss, not much choice if that is the distance to bridge.
Get a good antenna up, see forum here, and it will work fine.
3dB loss is just noticable, so don't sweat.
Is there lower loss cable out there? yes, but the price and connectors will be a LOT more expensive.
When the antenna is good i dont see chance on interference, good brand/quality coax can last decades.

 

[543_Dallas]

It's a long run but it will work fine. Here is a coax loss calculator that might help you decide if it's worth upgrading to larger coax.

https://www.qsl.net/co8tw/Coax_Calculator.htm

As you can see going to LMR 600 wouldn't help much.

 

[Shadetree Mechanic]

Personally, I would not run coax through the air. I would take it straight down from the antenna and run it underground.

 

[W4KVW]

Bringing any feed line thru the attic or any part of a home without a way too disconnect it outside of the home during severe weather is a Bad Idea.I have seen first hand what happens to the coax from a lightning strike & it could very easily result in your home burning down.Lighting should not be taken lightly.Give it the respect that it deserves & don't lose your home or life for a radio.

SIX-SHOOTER

 

[Tokin]

Absolute bad idea to run your coax thru the attics because of fire issues as stated.
Personally id bury some 1/2" hardline/heliax from the tower to the house.

 

[Tokin]

@Grandpap, whats your location?

 

[Grandpap]

Personally, I would not run coax through the air. I would take it straight down from the antenna and run it underground.

I hadn't thought about burying it. I had thought about running a cable between the house and garage, and tie-strapping the cable loosely to that.

 

[Grandpap]

Bringing any feed line thru the attic or any part of a home without a way too disconnect it outside of the home during severe weather is a Bad Idea.I have seen first hand what happens to the coax from a lightning strike & it could very easily result in your home burning down.Lighting should not be taken lightly.Give it the respect that it deserves & don't lose your home or life for a radio.

SIX-SHOOTER

Okay. What would you recommend for another option? What do others normally do when bringing coax from the tower into the house?

 

[Grandpap]

Absolute bad idea to run your coax thru the attics because of fire issues as stated.
Personally id bury some 1/2" hardline/heliax from the tower to the house.

That sounds like a good idea!

 

[Grandpap]

@Grandpap, whats your location?

West Virginia.

 

[Grandpap]

160 feet will be about 1.2 dB loss, not much choice if that is the distance to bridge.
Get a good antenna up, see forum here, and it will work fine.
3dB loss is just noticable, so don't sweat.
Is there lower loss cable out there? yes, but the price and connectors will be a LOT more expensive.
When the antenna is good i dont see chance on interference, good brand/quality coax can last decades.

Great! Thanks for the info!

 

[Grandpap]

It's a long run but it will work fine. Here is a coax loss calculator that might help you decide if it's worth upgrading to larger coax.

https://www.qsl.net/co8tw/Coax_Calculator.htm

As you can see going to LMR 600 wouldn't help much.

View attachment 41312 View attachment 41313

That's what I needed. I was afraid I would lose all my gain due to the crazy coax routing and excessive length. Thanks!

 

[Shadetree Mechanic]

I hadn't thought about burying it. I had thought about running a cable between the house and garage, and tie-strapping the cable loosely to that.

That would work and it may not cause any issues, but there are many things to consider. I will see if I can find a link to a previous thread about grounding and the National Electrical Code. There are 3 types of grounding for the system (station and antenna combined). There is electrical ground as in the power feed coming from the electrical company, lightning protection ground, and RF ground. Basically you will need to ground the coax braid with a ground rod at the antenna mast base among other things that are required to meet the electrical code. If it were to cause a fire and didn't meet code, then the insurance won't pay out. This also puts the coax at ground level and would be easier to go under ground from that point. It doesn't have to be deep. A sidewalk edger could cut a slit in the lawn and it could be stuffed in. You could just string it up as I am sure many people do and like many things, it would be ok right up to the point that its not.

If anyone has some good links, please put them up.

 

[Shadetree Mechanic]

Here is some reading:

https://www.w8ji.com/station_ground.htm

https://helpdesk.flexradio.com/hc/e...n-the-Ham-Shack-Paradigms-Facts-and-Fallacies

http://www.arrl.org/grounding