10 to 40 long wire ant

[BJ radionut]

Kevin: Random wire length vs. Doublet wire length are two totally different systems.
A Doublet is a Balanced antenna system, whereas a Random wire, even fed against a good counterpoise system is necessarily true.
http://www.m0pzt.com/baluns/
http://www.m0pzt.com/blog/4to1-current-balun/

 

[BJ radionut]

http://www.randl.com/shop/catalog/p...ts_id=39118&osCsid=dahuhs0m4c3k4vh35dndedrk27

 

[Captain Kilowatt]

Next weekend I plan on making another long wire Multiband antenna with 148 feet of wire . It’s gonna be a dipole split at 74 feet. I am going to use 125 feet of 450 ohm ladder line feeding into my shack.

First of all a slight correction. If it is split and equal lengths on either side it is a doublet not a long wire regardless of how long the overall length is.

Do I need to utilize a 1:1 Balun “IF” it’s going to be fed into my MFJ 939-I tuner?

YES you need a balun. That tuner does not have one builtin and even if it did most internal baluns are pretty cheap and external baluns are much better. Question: why 148 feet overall? A good effective multiband doublet is about 105 feet overall and when fed with ladder line is quite effective. That is what I ran for years. I ran coax cable to the other end of the house and to a remote mounted auto tuner. I made a choke balun from two parallel pieces of #14 household wiring wound biflar style of a plastic form about 2 inches in diameter and 10 inches long. It worked quite well.

 

[TruckerKevin]

Hi Captain

I chose the length based off this

http://www.arrl.org/random-length-multiband-dipoles

But I increased tthe length based on this warning

http://www.hamuniverse.com/randomwireantennalengths.html

If I’m doing this all wrong I’m very open to correction.

My goal is to get on as many bands as possible on my icom 7300. I am a new ham user, just passed my 2 tests a week ago today. I can’t transmit as of yet, but I’m getting everything ready.

Right now I am on 40 meters on an old extension cord I made, it works well for what it is. I just wanted to expand mostly to 80 and 20. I have a vertical that I can tune Some other bands on

 

[BJ radionut]

http://www.n4ekv.com/tuners.asp

 

[BJ radionut]

http://www.hamuniverse.com/hfdoublet.html
Here is that link again Kevin:
468 / 3.700 = 126.5 FT. overall then divide again for EACH side of center 126 / 2 = 63 ft.
I used 62.5 ft. but again the is not supercritical.
Like CK, used 105 ft overall. Just about any length in that range will work.
Don't get wrapped up in the length crap, again Random wires and Balance doublets are totally different systems.
Same with the length of the Ladder line and or Twin lead length. Many theories out there, the main objective is to get up and running, small tweaks came come as you use the antenna and tuner system.
Until you get going you don't know how it will perform and what adjustments are required.
No two antenna set-ups work the same in every location or installation, it's ALWAYS work in progress
Were here to help
All the Best
Gary

 

[TruckerKevin]

Gary I’m going to build mine exactly like you linked.

I just want something to work. I’m not trying to be an antenna scientist lol.

I want to try and get 80, 40 and 20 if at all possible. Those are my 3 goals.

I’m still waiting on all the parts so it probably won’t happen until next weekend.

 

[BJ radionut]

Kevin: Here is another Tip to Note:
NEVER-NEVER coil up extra Ladder Line or Twin Lead...
Use whatever length is enough to get to the shack.
Also good practice on a Doublet or even a coax fed dipole, you want that feedline to drop straight down from the antenna as far as possible, at least 20-30 ft. this does affect how it will tune.

 

[BJ radionut]

Kevin: If you have not ordered the Ladder Line here's another option to make your own.
Simple and they work great!
http://www.dtsohio.com/73cnc/laddersnap.html

 

[TruckerKevin]

I already ordered a 125 foot roll of it but that stuff is fascinating

 

[BJ radionut]

Just some pictures on how the Ladder line/twin lead /open wire line can be used.
When using on a metal mast, a good practice is to keep it at least several feet away from metal. Another thought it should not run close to any other feedlines. Thus you need another path thru the wall, not laying with or along with coax.
I use a 1 1/2 inch PVC sleeve thru the wall about 6 ft. above my bench, this is a separate path than I use for coaxes which come in under my bench.

 

[TruckerKevin]

So the formula to get 80 meter comes to be 58 1/2 feet per leg. You made yours 62 1/2, you allowed yourself 4 extra feet per side as a buffer?

Then I can expect the Balun to balance it and the tuner to utilize the needed length,

Then the lower bands (40, 20,) the antenna tuner will shorten the length it needs to resonate on those bands.

Does this pretty well summarize it?

By the way conditions are great on 40 meter today. I’m receiving people all over even in Guatemala

 

[Captain Kilowatt]

Hi Captain

I chose the length based off this

http://www.arrl.org/random-length-multiband-dipoles

But I increased tthe length based on this warning

http://www.hamuniverse.com/randomwireantennalengths.html

If I’m doing this all wrong I’m very open to correction.

My goal is to get on as many bands as possible on my icom 7300. I am a new ham user, just passed my 2 tests a week ago today. I can’t transmit as of yet, but I’m getting everything ready.

Right now I am on 40 meters on an old extension cord I made, it works well for what it is. I just wanted to expand mostly to 80 and 20. I have a vertical that I can tune Some other bands on

You are taking long wire info and applying it to a doublet. It's not that easy. One thing I can almost guarantee is that regardless of the length of the antenna and the length of feedline there may be problems tuning up on one band or another. You may have to adjust the overall antenna length and/or feedline length to be able to tune all bands. I initially had a problem tuning both 20m and 80m. I could get one band or the other but not both at the same time. I ended up shortening the antenna a bit and lengthening the feedline about 15 feet to shift the impedance enough for the auto tuner to tune 20m and 80m. All the other bands tuned fine. All band antennas and ladderline feedlines USUALLY require a bit of experimentation to function on all bands.

 

[Captain Kilowatt]

As a note it is best to make several twists in the ladderline, one full turn every 6-10 feet or so, to prevent the wind from whipping it around. It tends to act as a sail and can REALLY whip around. The twists tend to balance out the forces and although it will still be affected by the wind it will not whip around as violently in high winds.

 

[TruckerKevin]

One of my thoughts was to “thread” Dacron rope through the ladder line and let the Dacron be the actual strength, that away I don’t have the wind pulling on the ladder line.

Or is that a bad idea?