Quick simple question-Running coax down mast??

[jody_clarke]

Am finally ready to mount my Diamond DJ-130NJ to a 50' Channel Master galvanized steel mast. Question is will it create any problems if I was to run my coax ( 85 total feet of LMR-400) down center of mast? Realize this is a very simple/newbie type of question, yet after searching I didn't find anything on the subject- so am guessing it's a non issue?? Just wanted to make sure before I did final install, as in the pas I've always let the cable swing in the wind.
Thanks for everyone's input throughout this process, J. Clarke

 

[SurgePGH]

Am finally ready to mount my Diamond DJ-130NJ to a 50' Channel Master galvanized steel mast. Question is will it create any problems if I was to run my coax ( 85 total feet of LMR-400) down center of mast? Realize this is a very simple/newbie type of question, yet after searching I didn't find anything on the subject- so am guessing it's a non issue?? Just wanted to make sure before I did final install, as in the pas I've always let the cable swing in the wind.
Thanks for everyone's input throughout this process, J. Clarke

As in running INSIDE of the mast pipe? I wouldn't recomend it for the simple reason that there will be nothing supporting the weight of the LMR. If the LMR is on the outside of the mast pipe you should be attatching the LMR to the mast in intervals to help keep the weight of the LMR from pulling on the connector as well as stretching itself. Same goes if you run it inside the mast pipe. You don't want it to stretch itself.

 

[n5ims]

Another issue with running the coax inside of the pipe is the rough edges on both the top and bottom of the pipe could easily scrape the coax and cause water penetration (and associated failures) as the coax moves around either due to the wind or pipe swaying around. With a sectional pipe, this issue is not only at the top of the mast, but at each joint as well and since this is hidden, you'll never notice the damage until it's too late. While you probably can put some kind of protection on the very top and bottom (such as a section of plastic to keep the coax from touching the pipe itself), this won't work at the joints so this will still be an issue if you have a sectional pipe mast.

 

[K9WG]

Just run it outside of the mast and secure it with UV resistant wire-ties being careful not to deform the cable. A good quality COAX should hold up to the outside environment. Also be sure to seal the connector at the antenna. I used Coax Seal Web site and after three years my connector looked like new when I removed it.

 

[LtDoc]

Except where the coax didn't have to follow the mast for whatever reason, I think every installation I've had was with the feed line just taped to the mast. Any unwanted consequences with doing it that way? Not that's ever shown up for me, or that I know of. It's a very common way of doing it.
Wanna try doing it some other way? Have at it! If it makes any significant differences, tell us about it.
- 'Doc

 

[kb0nly]

I prefer to wrap with 2-3 wraps of 3M super 33 electrical every 1-2 foot depending on cable size and height. Cable ties dig in and leave marks after a while and also rub into the insulation. I saw this on one install a couple years back, UV resistant black cable ties all the way up the mast, when i clipped the cable ties each one left a indent and even a rubbed through spot in the coax. If you put them too tight you dent the cable, too loose and the rub in the wind, there really is no perfect tightness of a cable tie on coax, tape is much much better.

 

[KC4RAF]

As all the other posts,

run the cable outside of the mast. Weight is your problem if not secured every few feet. Also, weather proof your connection at the antenna jack/plug. Use a good quality splicing tape for this and then a layer or two of good electrical tape to finish it off.

 

[majoco]

I'm with kBOnly on this - also make the coax a little slack in between the tape ties.

 

[KC0FZZ]

About the only real reason I could see for running the coax inside the mast would be if you're in a suburban environment, and you have an Earth-first greenie whacko for a neighbor who thinks he's doing "mother earth" a favor by destroying a radio transmitter, or some know-nothing who blames every pixelized tv picture on your big bad "CB" radio.

In those cases the whackjobs favorite method of attack is to pin (or cut) the coax.

Since electrifying your tower with a neon sign transformer is probably illegal at worst and detrimental to your signal at best, and most suburban and city ordinances frown uipon barbed wire obstacles around your tower, you may want to secure the coax as best as you can so that there's no weight issue and then run the coax into the ground through some good thick electrical conduit and then into your shack.

Of course, this only really applies if you're concerned about some schmuck trying to destroy the fruit of your hard work and interefere with the enjoyment of your hobby.

Of course, I'm only ranting about things I've heard in the past-this is in no way an endorsement of nor a condemnation of any one (sane) person or group of (sane) people.

A note on zip ties-use 'em sparingly. As others have said, if you pull them too tight, they *will* damage the shielding of your coax, sometimes right away and sometimes with time.

 

[wv_mountaineer]

I used Coax Seal Web site and after three years my connector looked like new when I removed it.

Would something like "liquid electrical tape" or the rubberized dipping liquid for the end of tool handles like channel locks or pliers work just as well? You can buy this at hardware stores, home depot or lowes. It comes in 8oz. cans with a brush. And all you would have to do is brush it onto the end of your coax and it forms a rubber seal around your connector. I don't know how hard it would be to get this stuff of if you had to but, would this stuff work just as well?

 

[kb0nly]

The liquid stuff doesn't work that great for connectors, i have tried it. It loosens up over time. If you use the liquid you still need to follow up with some rubber tape over the top of it to truly waterproof it.

Look in that same isle for the splicing tape, its a rubber tape with a liner you take off the one side as you unroll it, you stretch it a bit and overlap it like you would wrapping something with electrical tape, but it bonds into a solid piece of rubber after a short time. I generally put two layers, starting from opposite ends for good overlap and go onto the coax about an inch beyond the connector and as close as possible to the antenna end if the connector goes onto an antenna. Then if its going to be exposed follow up with two layers of 3m Super 33 electrical tape for UV resistance. You can come back years later and slice it down one side and pull it off like a molded rubber boot and everything will look like new.

A lot of the diamond antennas has the base of the antenna sitting down in a mounting tube, if thats the case then you don't need to cover it up with electrical tape as the UV can't get to it, but the extra step of the electrical tape surely doesn't hurt!

 

[kb0nly]

SELF-FUSING RUBBER TAPE | AllElectronics.com

My local stores have started carrying the linerless version of the splicing tape, doesn't seal as nice as the regular version in my opinion, since availability seems to vary here is a link of where i have been buying it lately.

Just make sure whatever you get is self amalgamating with a liner on one side, the linerless splicing tape doesn't do nearly the same job for waterproofing, it works good for insulating electrical connections but not not making them watertight.

 

[Confuzzled]

Side question........

To bring four coax down the same mast, three receive only (UHF/VHF), one low power transmit/receive (800-900Mhz), can they be bundled or should they be separated?

 

[KC0FZZ]

Side question........

To bring four coax down the same mast, three receive only (UHF/VHF), one low power transmit/receive (800-900Mhz), can they be bundled or should they be separated?

In theory, due to the nature of coax, you should be able to run all of the cables together.

The idea is that the shield is connected to ground and any noise picked up will be grounded by your station grounding connections. The center conductor is what carries your desired signal down to the radio, and up to the antenna in the case of a transmitter. For recieve only setups, as long as they're separate radios, you can mount the antennas just about any way that fits, when transmitting comes into play there will be a minimal separation required between antennas.

Or course, in practice, your milage may vary.

 

[kb0nly]

My one tower has 8 feedlines coming down the same leg all in a big bundle, don't worry about it...

Have you ever seen a commerical tower? I know plenty that have dozens of cables all in one big bundle coming down a leg.

 

[Confuzzled]

Our public 150+ foot tower has them separated and spaced, so I guess that's a preference of the tower tech.

I didn't think it would be much of an issue on a 50' home mast.