Extra Antenna Cable

[mcdogg]

What is the best way to store the extra cable going to my scanner?

I believe that I read somewhere that it can mess with the reception if it is not stored correctly.

Thanks

 

[Rt169Radio]

What do you mean? Do you have extra cable that you not going to use or you have extra cable that is attached to your scanner?

 

[michaeldim]

I imagine he means that the cable from his antenna to his scanner is too long and he's wondering how to store the excess without picking up a ton of interference.

 

[N2ICV]

Whatever you do, don't put it in a loop, put in a figure 8 pattern.

If you store it in the loop it will act as a choke.

 

[Adenosine]

Whatever you do, don't put it in a loop, put in a figure 8 pattern.

If you store it in the loop it will act as a choke.

Then why do you see a loop at the base of some antennas?

 

[lep]

Some believe that the loop will help protect against damage from a lightning strike on an outdoor antenna since the energy can't follow the turns easily.

Me? I prefer Polyphasers.

 

[WA0CBW]

A lot of myths going on here. A loop at the base of an antenna will offer NO protection to lightning damage. It will offer some rejection to RF coming down the coax on the outside of the shield but only if it is a transmitting antenna. The method of handling excess cable has no effect unless you make the coils smaller than the bending radius of the coax which could short or change the impedance of the cable. Coiling or figure 8'ing the coax has no effect on its performance unless it is a transmitting antenna and you have RF on the outside of the coax. However excess coax does add additional attenuation to the received signal. It is best to cut the cable to the length needed. Unless like all good radio enthusiasts you are planning on adding 10 more feet of height to the mast or tower. I know I am....................someday!

 

[W6KRU]

When a balanced antenna(dipole) is fed with an unbalanced line(coax), it can cause common mode current flow which can be eliminated with an ugly balun.

 

[W2NJS]

WA0CBW wrote above:

"A lot of myths going on here."

There's a lot of that goes on here on this Board; that an plain old misinformation.

 

[dave3825]

Some believe that the loop will help protect against damage from a lightning strike on an outdoor antenna since the energy can't follow the turns easily.

Me? I prefer Polyphasers.

Lightning takes the path of least resistance. A straight wire vs a coiled wire makes no difference. It will flow thru the conductor to no matter what....

 

[ka5lqj]

"Ugly Balun"......

When a balanced antenna(dipole) is fed with an unbalanced line(coax), it can cause common mode current flow which can be eliminated with an ugly balun.

An Ugly Balun? I know some fellas that resemble that remark, but I'm NOT
one of them, ROFL!

Now, when I was running my Double Bazooka on 80-6 meters with an MFJ-943 tuner, I had a coil of about 8 turns over an 11.5 ounce coffee can
(removed) and taped together with electrical tape It worked find and the author of the article actually recommended that you did that after building the antenna. The ONLY band I could not work And I didn't want to work it
anyway, was 15 meters. I never tried it on 60 meters but it did work well on the other WARC bands. The coax used for both the antenna and feed-line was R$ RG-8X.

GOD BLESS,
73,
Don/KA5LQJ

 

[jim202]

A lot of myths going on here. A loop at the base of an antenna will offer NO protection to lightning damage. It will offer some rejection to RF coming down the coax on the outside of the shield but only if it is a transmitting antenna. The method of handling excess cable has no effect unless you make the coils smaller than the bending radius of the coax which could short or change the impedance of the cable. Coiling or figure 8'ing the coax has no effect on its performance unless it is a transmitting antenna and you have RF on the outside of the coax. However excess coax does add additional attenuation to the received signal. It is best to cut the cable to the length needed. Unless like all good radio enthusiasts you are planning on adding 10 more feet of height to the mast or tower. I know I am....................someday!

OK guys and galls, I have to agree that the myths are flowing well today.

First of all, those that have not been around towers with a coil or several coils of coax tied to a mast or leg of a tower need to take a close look the next time they see this. Look close between the metal of the tower and the coax. Notice the black soot or the remains of it after several rain storms have done their work. What your seeing is the remnants of where there was an arc from the coax to the tower leg from a lightning strike.

As has been stated on here already, the lightning doesn't like to make sharp curves. It really is looking for the path path of least resistance. The coil in the coax has done it's part in creating a choke and caused a high resistance to the path of the lightning.

Those that think this is an old wife's tale, better go do some homework in understanding lightning. How to ground a radio tower to prevent damage. Those that propagate the story that a tower can't take a direct strike and still have the radio equipment stay operational better also do some homework.

Why am I saying this? Well I have seen a 500 foot tower take a direct strike, come out of it with the tower steel steaming in the rain from the heat that was generated from the high current flow to the ground. I went inside the equipment shelter and all the radios were playing away just fine except for one. Yup, guess who owned the one that was dead? It belonged to a couple of ham radio operators that just refused to ground their radio cabinet like everyone else in the shelter. They refused to put surge protection on the coax cable and refused to put surge protection on their AC power feed.

Spent 18 years engineering, building, optimizing and measuring ground systems around the country for several cellular companies. They take hits all the time from lightning. Very rarely is any damage done. When there is damage, it generally is because someone took a shortcut and didn't do the install like they should have. Do you think radio, TV and cellular companies along with public safety radio systems would survive if the installs were done sloppy or left out some of the grounding and tricks to keep the radio equipment running? They can't afford to let that happen.

So lets stop the spread of these old tales and tell it like it really is. If you have never been to a radio site and seen just what is done to make them survive, take the effort and make the trip. It would be even better if you could be there when they first start to install the grounding system. Then arrange to come back when all the work is done and the radio equipment is in and operational. You just might learn something.

 

[ka5lqj]

Lightning protection...

Hi Jim, All,

I was being a smart asp about the ugly balun. Where I used to live my double bazooka was at 50 feet and still below the tree coverage. Where I live now, is a different story. The lot is only 50' wide but about 400' long and I'm hoping to put up two, 120' guyed towers. I'll ground my towers and antennas properly and install some "Blitz Bugs" to take any static or lightning charges. Both towers will be using 2/0 welding cable tied in a circlar pattern around the tower with 15 foot grounding pipe. Here the soil is mostly clay and being near the Lake, it's moist most of the time, a perfect place to go to ground.

During a severe thunder and lightning storm, I'll remove all the coaxes and put them out the window and away from the camp house. I've got an Icom 706 MarkII-G and an old Heathkit 2046 that I can run deep cycle marine batteries on to get on 2 meters if I have to.

Your advice sounds mighty sage and well worth pursuing.

GOD BLESS,
73,

Don/KA5LQJ
QCWA
10-10 International
Area 5 Wx Group

 

[lep]

In my personal home set up I have a loose coil of coax at the base of the tower, the end is attached to a bulkhead mount Polyphaser that is bolted to a leg of the tower. [to be technical, there are two coils, one for HF and one for VHF, there are two different KW Polyphasers for the appropriate frequency range].
Yes, I have had a direct strike that exploded the buried coax out of the conduit...made an expensive ugly mess but (1) no one was injured (2) the radios survived but not the coax/antennas/small hardware.

In my part of the nations it's just a fact of life.

 

[VO1GXG]

A lot of myths going on here. A loop at the base of an antenna will offer NO protection to lightning damage. It will offer some rejection to RF coming down the coax on the outside of the shield but only if it is a transmitting antenna. The method of handling excess cable has no effect unless you make the coils smaller than the bending radius of the coax which could short or change the impedance of the cable. Coiling or figure 8'ing the coax has no effect on its performance unless it is a transmitting antenna and you have RF on the outside of the coax. However excess coax does add additional attenuation to the received signal. It is best to cut the cable to the length needed. Unless like all good radio enthusiasts you are planning on adding 10 more feet of height to the mast or tower. I know I am....................someday!

Well said!