Beginner ham antenna questions

[bhayles]

If you want play around different antennas without going broke, use steel electric fence wire. Then once you decide what you like best, make one out of copper.
Rich

Rich...what about aluminum electric fence wire? Its pricey to have to buy, but I've got thousands and thousands of feet of it already bought.

I'm probably going to buile the 80-10 meter fan antenna as a permanent antenna right from the start, then build others to experiment with going forward.

 

[n8fgb]

Watch the breaking strength, and the electrical connection. I had a friend buy a quad, maybe Jem quad, tha came with a 1 lb spool aluminum welding wire.
Rich

 

[wavrider]

Rich...what about aluminum electric fence wire? Its pricey to have to buy, but I've got thousands and thousands of feet of it already bought.

I'm probably going to buile the 80-10 meter fan antenna as a permanent antenna right from the start, then build others to experiment with going forward.

Aluminum will work, as mentioned the tensile/breaking strength needs to be thought about.

The KJ4IIF Multiband "FAN" Dipole for 160, 80 and 40 Meters

good article on fan dipoles

 

[BJ radionut]

There are a few drawbacks to using ALM on antennas IMHO
ALM tends to weaken when bent or kinked, thus over time wind and vibration will eventually cause breakage. Solid copper will also, however copper is a much more dense material and those effects take considerably longer to occur.
Stranded Copper or Copper Clad steel core wiring is my preferred antenna wire.
Alm is harder to terminate, tho you can solder to it with special flux material, you must consider you will be connecting it with coax or Ladder line witch is copper and corrosion will begin in a matter of days(Oxidation). The exposure to outdoor elements, special care must be taken to seal the connections thoroughly.
Just a couple thoughts
All the Best
Gary

 

[bhayles]

OK...after agonizing over it I've decided to go with stranded copper for my first antenna project, the fan dipole. Later I might try the aluminum and/or galvanized electric fence wire, but for the first one I'm going to be simple and basic, not try to be cute.

I picked up abpout half the materials today and ordered the rest, so I'll be starting tomorrow and finishing sometime next week. I do have an observation and a question.

First, I'm building one of these two (very little difference):
MULTI BAND HF FAN DIPOLE ANTENNA DESIGN
The KJ4IIF Multiband "FAN" Dipole for 160, 80 and 40 Meters

...and I'm changing one thing. Both call for using pvc...the first a length of 4" for the ugly balun and 1/2 or 3/4 for the spreaders and the second for the spreaders.

Bad idea. PVC is very subject to UV and in a relatively short time will become VERY brittle...like in less than 2 years. The most similar, inexpensive material you can get, especially for the spreaders, is the grey plastic 1/2 or 3/4" (for the spreaders. I don't know if it comes in ~4" for the balun) electrical conduit sold at any home improvement center. Its cheap, will do the job, and is impervious to UV.

Now my question. I don't know that I want to get too ambitious on my first antenna. Should I go all the way and do radials for 10, 20, 40, 80. and 160 meters, or leave off the 160? Is there much activity on 160? I'm thinking maybe I should go with just 10, 20, 40, and 80 meters.

Y'all say what?

 

[w9cll]

How much room do you have? 160 is a lonnng antenna.personally I would do 10, 20 and 40. 15 meters will load on the 40.

 

[n8fgb]

I would not try to build the entire antenna at once. Build it as a monobander, tune it, then add one band at a time. Tune each band as you add and check your other bands as you go along. It can get pretty confusing.
Rich

 

[bhayles]

How much room do you have? 160 is a lonnng antenna.personally I would do 10, 20 and 40. 15 meters will load on the 40.

Antenna size itself won't be an issue. I have 2 1/2 acres out in the country with no zoning restrictions on Ham antennas.

My property is also heavily wooded...lots of "poor man's towers".

Question...aside from room, do I really need 160 meters? Does it get much use? Heck...according to the user manual the first radio I am going to have...a TS 130S, doesn't even HAVE 160 meters...

 

[wavrider]

Bad idea. PVC is very subject to UV and in a relatively short time will become VERY brittle...like in less than 2 years. The most similar, inexpensive material you can get, especially for the spreaders, is the grey plastic 1/2 or 3/4" (for the spreaders. I don't know if it comes in ~4" for the balun) electrical conduit sold at any home improvement center. Its cheap, will do the job, and is impervious to UV.

Now my question. I don't know that I want to get too ambitious on my first antenna. Should I go all the way and do radials for 10, 20, 40, 80. and 160 meters, or leave off the 160? Is there much activity on 160? I'm thinking maybe I should go with just 10, 20, 40, and 80 meters.

Y'all say what?

PVC?? If you must it can always be painted for UV protection.

That same antenna is still up and still working GREAT. I am in Florida so a lot of UV here.

I would suggest the 20/40/80 meter dipoles, you can work 25 meters on the third harmonic of the 40 meter leg so four bands, coax feed. with no antenna coupler required.

160 has some activity and is mostly a winter time band.

The balun is one of the most important parts of the antenna system I HIGHLY suggest a good 1:1 current balun.

A good current balun will assist in distributing equal currents into both legs of the dipole. Helps prevent CMC/TVI/RFI.

On the particular fan dipole you will be using 21mhz down to 3.8 mhz, an rf choke at the feed point will not really be a rf choke at all those different frequencies.

I have built and installed four of those fan dipoles, at different locations and all of the fan dipoles pretty much were resonant at the frequency of design.

Inverted V configurations is needed for resonance on all bands.

The best part about wire antennas is if you get tired of it, take it down and re-use the wires for another type of antenna

 

[Captain Kilowatt]

How much room do you have? 160 is a lonnng antenna.personally I would do 10, 20 and 40. 15 meters will load on the 40.

Yeah, like about 250-260 feet long depending on tuning. I had a 160m dipole once but it was more an experiment in worm warming than anything. I got great reception on the top of the AM broadcst band however.

I would not try to build the entire antenna at once. Build it as a monobander, tune it, then add one band at a time. Tune each band as you add and check your other bands as you go along. It can get pretty confusing.
Rich

The only problem with that is that when you add another wire for another band it throws the tuning off of the existing wire. With a fan dipole you should install all the wires for the bands you want to use and then start trimming the highest band (10m) first. This will minimize interaction as you progress trimming the other bands.

 

[bhayles]

RF choke needed?

I've read four articles on Ham Universe on the multiband fan dipole. The first has an item referred to as an "ugly balun" buit diesn't have any windings, see here:

MULTI BAND HF FAN DIPOLE ANTENNA DESIGN

here:

KL3JM MODIFIED "SRI" MULTIBAND FAN DIPOLE - 80-40-20 METERS

and here:

The KJ4IIF Multiband "FAN" Dipole for 160, 80 and 40 Meters

It looks to me that what is referred to as an "ugly balun" is really just a connection point that brings the dipoles together to connect to the coax, right?

But then I see this article, also from Ham Universe, and it also uses the term "ugly balun" but in describing its construction he actually builds a coil with coax:

The Fence Fan Dipole by W6HDG - A Quick, Easy and Inexpensive Multiband Antenna

So...is the choke type balun used in the last article necessary, or should I just use the center as a collector point for the dipoles and feedline as in the first articles?

Also, I'm not seeing how the connection to the feedline works. In a 4 band fan, do I collect all 8 dipole halves using the copper connection strap, then soldering the two straps to the center conductor of the coax (and if this, I connect the coax shield to...what?) or do I solder the copper strap on one side with one dipole for each band to the center conductor and connect the other copper strap with the other dipole halves to the coax shield?

 

[The DB]

So...is the choke type balun used in the last article necessary, or should I just use the center as a collector point for the dipoles and feedline as in the first articles?

Also, I'm not seeing how the connection to the feedline works. In a 4 band fan, do I collect all 8 dipole halves using the copper connection strap, then soldering the two straps to the center conductor of the coax (and if this, I connect the coax shield to...what?) or do I solder the copper strap on one side with one dipole for each band to the center conductor and connect the other copper strap with the other dipole halves to the coax shield?

You don't technically have to have anything between the coax and the antenna, and there are people who have nothing there with great success. That being said, most people use a balun, ar at least a choke, with good reason.

The other side of the spectrum is a balun. This both isolates the antenna from the feedline and forces the signal at each leg of the antenna into balance.

In between there is a choke. Many people call them air chokes or "Ugly Baluns", but know that it is not a balun because doesn't force anything into balance.

Another drawback of air chokes is the bandwidth they function over. Compared to a current balun, which can typically operate over the entire HF spectrum, they have a much smaller range of frequencies they function over. Further, because of how they work, depending on the length of coax and other properties, it is possible for them to make a problem worse on some bands of operation while others appear to have no choke at all.

If you decide to go the choke route you may consider something with a ferrite, although it really isn't that expensive to get an actual current balun that can easily handle 100 watts, and not to difficult to make one yourself either...

When making a fan dipole you connect all the legs on each side to the same point. One side may be connected to the center conductor in the coax while the other is attached to the shield. On a balun you have two outputs, one is one side and the other is the other...


The DB

 

[Road Squawker]

... The first has an item referred to as an "ugly balun" buit diesn't have any windings...
It looks to me that what is referred to as an "ugly balun" is really just a connection point that brings the dipoles together to connect to the coax... it also uses the term "ugly balun" but in describing its construction he actually builds a coil with coax:

an "ugly" balun is not a balun at all, it doesn't connect a balanced feedline to an Unbalanced line.

the loops of coax are really just an RF choke coil

 

[bhayles]

an "ugly" balun is not a balun at all, it doesn't connect a balanced feedline to an Unbalanced line.

the loops of coax are really just an RF choke coil

So...with what I'm building...a balanced fan dipole, I need nothing, or a choke coil? If I were building an off center fed fan dipole, like a 1/3 fan dipole, THEN I would need a balun, right?

 

[bhayles]

I don't see an admin section here...does this forum work on Tapatalk?