Introduction: G5RV Jr. (Half Size) Ham Radio Antenna

This project gives instruction on how to build my version of the G5RV wire antenna that is used on the 10-40 Meter Ham Radio bands (28MHZ to 7MHZ).

The history and basic theory of this antenna dates back to 1946. It was invented by Louis Varney. More technical information can be found at the following link . I WOULD STRONGLY ENCOURAGE YOU TO READ THIS LINK and vew it's contents including the diagram so that you have a mental image of where we are headed.
 http://www.qsl.net/yb0emj/tech.htmlI
 
B
y Googling G5RV will also give you information and other ways to make and use this antenna.
Let me clarify that I DID NOT INVENT this antenna, I just built my own version of the original.

I have not posted yet a picture of the antenna in it's final hanging location as this is going to be a portable antenna that will be put up and taken down likely in the same day.

Step 1: The Components of the Antenna

The wire used for this project Is green UV resistant vinyl coated, phosphor bronze stranded wire.

You could use any copper wire but note that pure copper wire will stretch over time more that what I am using.  When wire antenna's stretch that also de-tune downward in frequency as they become longer.
The bronze wire is extremely strong and will last a life time, I'm sure it's weight rating is way over 1000 lbs.

For this antenna you will need two pieces of wire 26Ft long. 25.5 is the finished length aprox. I have extra to get around the insulators and to wrap and solder.

I chose to use ceramic egg style insulators for several reasons.  Most of you would look at these and say WOW that is overkill! First off I chose them because they were all I had in the junk box and I didn't want to invest more money  at the time.

I also wanted to have insulators that had weight to them so I could put one end of the antenna elements over a tree limb if there was an emergency or I was in a hurry if needed. This way if it was bad weather I could let it hang and not need to tie it off as I normally would do.

Since the insulator electrically separates the RF energy on the antenna element/wire from the non conductive support it needs to keep the two from touching. Often when transmitting on certain frequencies there will be a very high voltage at the outer ends of the antenna. This voltage can start a fire or melt a plastic insulator if not installed  correctly or the wrong insulator is chosen for the job.
It is not impossible to have several thousand volts at the end of an antenna. NEVER touch an antenna while it is in use unless you know what you are doing!!!

I chose a 4way 1/2" pvc junction as my center insulator. I did this mainly to facilitate supporting or hanging the antenna from the middle (which should always be higher than the ends.)
With this insulator I am able to insert 1/2 pvc pipe to  support from under or over the antenna to hang from, how ever I choose. Use your imagination on this and you can dream up a number of ways to support this antenna.

 I will use a piece of 550 Para cord run through the open ends to hand the insulator allowing the Ladder line to drape downward to the ground. It is advisable to hang this antenna as high up as possible. Getting its at least 20 feet up on a tree branch or some other non conductive support would be suitable.

The Ladder/Window line is aprox 450 Ohm impedance. You will be using 16.5 ft of this line. I suggest cutting it 6-8 inches longer so that you have room to make attachments with solder at both ends. With the use of an HF tuner between the transmitter and the antenna any finished length between 15.3 and 16 Ft should give you a good SWR match on all bands.

Lastly (NOT SHOWN) you will need a piece of 50 Ohm Coaxial line. RG-8, RG-8x, RG-58U will all work depending on the wattage you plan to run with and the length of the cable,  and loss you want to incur.  An RF fitting to match the antenna output of your tuner will be needed these are usually PL259 , N type, or BNC connectors.

Some articles about the G5RV say you can use any length of coax you choose. This is a disputed fact so you  may have to play with the length to get a good match.





Step 2: The Tools I Used

As you saw in prior pictures I used a small butane pen touch to solder with. You could use a 100watt iron but this pen torch was easier. Honestly the soldering iron will need a lot of time to heat up this amount of metal and get a good joint.  You can purchase the torch for a few bucks at Harbor Freight you will also need a can of butane that you refill lighters with. also a couple bucks at places like walgreens, wal*mart and the like.

Since I have a back ground in metal work, soldering etc I chose the torch. JUST BE CAREFUL the torch is much hotter and will melt things you dont want melted. NEVER leave your lighter or butane bottle near your soldering site where the torch could graze them and  make them explode!!!  SAFETY FIRST !!!!!!!

I am using the thin 60/40 solder from RadioShack. This solder you can feed to the joint fast and have better control. With all solder connections FLUX is the key. You want to keep the copper from oxidizing before the solder flows. If the copper  is dirty/oxidized the molecular bond will not solidify and you will have a "COLD JOINT".  COLD JOINTS are a real headache in radio land.  
Resistance, arching, lack of strength are all things you don't want on a fun outing or in emergency communications.

You may have noticed I am using electronic wire clippers. these are handy for trimming the ends of wire sticking out from solder joints. Cutting ladder line insulation out to allow passage over the 4 way PVC center piece.

I use an old style hand crank drill for all my holes. (drill not pictured)

The blue clamp in the picture did a nice job holding the ladder line to the table/soldering block so that the torch work was safer and easier.

****** I also keep a small wet sponge near by for cooling joints and in case something drips or spills.******

Step 3: Putting Things Together Pt 1

I think these three pictures speak louder than words.
You want to drill holes in each ends and both side of those ends that fit the gauge or wire you are using.

I as you can see trimmed extra insulation out of one window space in the ladder line. This allows the conductors to go over the center  insulator like a pull over vest. This creates a nice support for the feed line and also takes stress off of the solder joints.

The zip ties do a nice job of keeping things in place without the use of glue, tape, or cement.

NOTE **** Since I am not permanently installing this antenna, I will not be taping or sealing joints at either end of the elements.****   <<< I want to see that the joints are in good shape when I take down and put up the antenna on each use.

As you can see from a close view you can see there will be several ways to hang this antenna from the middle.

Step 4: Putting Things Together Pt 2


Soldering the feed line ends to the dipole elements can be a chore if you are new at it.
As I said before clean well fluxed metal is what make the job easy and the end result strong.

For those of you new to soldering. MAKE SURE you purchase solder paste/flux separate from the flux that is in the middle of some solders. I happen to use Oatley's brand but any resin flux should do.  DO NOT USE ACID CORE SOLDER WITH ELECTRONIC SOLDERING.  To be honest I don't know if it is still made but if you have it don't use it for this type of project!!!

Fluxing the joints before heating will insure the metals to be soldered remain, or become clean.
a small soft water color paint brush, tooth pick or scrap of wire will work nicely to apply solder. don't be afraid of the flux, it's cheap and cleans off with warm soap and water after you get done. Make sure the area to be soldered is pretty well covered in a light amount of flux.

I have posted 2 images here of the joints. The first picture shows the wires wrapped around one another with the flux applied.  In the second picture You will notice how the solder flowed and created rounded connections between the metal types. This is called capillary attraction. When you see this happen you know the solder and the joint was hot enough to make a good solid molecular  bond. This will assure that maximum antenna voltage and current can pass through with out being hindered by resistance of some sort.

The idea of a good antenna is to get as much RF ( Radio Frequency) energy from the transmitter up the feed line, down the element and radiated into the air. The last thing we want is a road block or a lane closed :) I think you get the idea!

When you are done soldering use your clippers to trim the solder joints. Often there is a wire end or ends that need to be trimmed a bit.  Doing this keeps you from getting a cut on your hand or finger. It is a nice bit of house keeping before you wash the joint with your wet sponge.

The sponge will take a lot of the flux residue off of the joint.  If you want the joint real clean proceed to the sink with a drop or two of dish soap in your fingers and clean it that way, then rinse and dry.






Step 5: Putting Things Together Pt 3

You are almost finished!

You will need to solder your coax to the other end of the ladder line. The image on the link above shows the coax directly soldered to the ladder line. I chose to use a UHF SO239 connector out of the scrap box. You can also buy these from Radio Shack or on ebay at times. 

If I had had the money and wanted to take the time I would have enclosed this connection in a plastic project box. (Again Radio Shack). It would have made it look nicer and been perhaps safer in the long run.

By using the SO 239 female I can use any coax PL 259 coax I choose. It can be short, long, low loss like RG 9913 or RG 58u mobile type coax which is quite lossy for long runs ,yet very flexible.  ( Coax loss at HF frequencies is fairly low dB wise.) If I was doing this at VHF-UHF I would not even use the connectors because each has a loss component.

If I had a location other than my 3rd floor apartment I would permanently install this antenna. At that point if the feed line run was long I would likely use Low loss Hard Line  to keep the loss to a minimum.


You now have a visual of how I did my version of the G5RV multi band dipole.
I would encourage you to dream a bit about which version , be it DOUBLE size for all 6 bands,  FULL size for 5 bands, or Half Size "JR" for the 4 bands  that you want or need to build. 

Keep in mind this antenna can be built very light with smaller stranded wire or TV Twin Lead so it can be rolled up and put in a back pack for that hiking trip using a small CW transmitter for QRP << very low power.

I would enjoy hearing from you if you build or come up with other ideas for this antenna. Questions are also welcome along with comments.

As I use this antenna I will try to take some station picture so you can see it up and in action.
Thanks for reading this instructable!

Bryan  
kc8hps               ***** More about me and my interests can be found at  kc8hps.com


Comments

author
kydale013 made it! (author)2015-08-13

I am making my first ever dipole. I have only 10ga. Insulated stranded wire.

do I have to use ladder wire that I don't have lol?. Any info much appreciated.

Thank you. 73s. Km4htd

Dale in Kentucky

author
kc8hps made it! (author)kc8hps2015-08-13

Hi Dale,

I just looked up your QRZ page.
If you want real good antenna instruction check out the antenna design page at. www.hamuniverse.com There are many things to build there for almost any band you want to work. A standard dipole with an " ugly balun" << RF choke at the end of the coax where it feeds the dipole. It's basically winding up about 5-6 turns of coax, make it sloppy not neat. Zip tie. Or tape it in a few places to keep it tightly coiled. The coil will be about 5" ish in diameter.

Basically this choke keeps the RF signal up on the dipole instead of letting part of the RF come back down the outside of the coax shield . You get much better performance that way.
The G5RV that I posted here the ladder line forms an RF transformer. An ugly balun would not work on it.
More questions? Ask away.

73. Bryan. KC8HPS

author
kc8hps made it! (author)2014-10-12

Yes 300 ohm line should work fine for low power and much lighter as well.

author
n0klu made it! (author)2014-10-12

In lieu of the ladder line I use 30 feet of 300 ohm twin lead and soldering any length of coaxial cable ( any ohms only with braided shield not the solid wrapped shield) and a PL238 at the end

author
Ray-l-l made it! (author)2014-04-17

Nice to see a ham antenna on here. Nicely done job.

73 de WD5DHK

author
kb3zhx made it! (author)2013-03-20

Thanks Bryan,

I cut the full size G5RV to match your dimensions listed here.. and Wow! It fits nicely as a flat-top dipole in my yard (hanging up about 30 ft high - attached on one end to a tree and the other to the house.) I have to do some fine tuning, but it works wonderfully on all bands with a tuner - except for 10 meters where it is perfectly resonant in the cw portion of the band. Worked qrp to Argentina and Chile during a 10m band opening!

Q: What is the exact length of your 450 ohm ladder line? Mine ended up being 16' 8" Maybe a fine tuning of this length would help it to resonate better on more bands??

Since the wire size of this MFJ-built antenna is kind of over-kill for back-packing, I'll definitely be making a lighter version of this for field use.. Keep up the good work!

73 Brian KB3ZHX

author
kb3zhx made it! (author)2013-03-17

Thanks for the great info... I bought a G5RV (full size) antenna from HRO recently for temporary field operations. Now that I haven't used it in such a long time in the field, I want to cut it down to a G5RV Jr. so I can fit it on my property for a permanent install.

Anyone try this before? Seems the dimensions here will work and I'll just be cutting all wires approximately in half to convert the full size G5RV to the Junior model since it is fed with the same 450 ohm ladder line.

author
kc8hps made it! (author)kc8hps2013-03-17

Hi Brian, Bryan here kc8hps,

Thanks for the comment. Yes I think the half size is easier to transport. I could have used a narrower gauge of wire but sticking with the phosphor bronze It was the only size I had in the old wire bin :)
I tend to recycle/re-purpose things as much as possible.

I think in your case where you have the 817 for your mobile (read your qrz page) I would make a half size version you could put in a ziploc back and take with you on a day long hiking trip?
73's k8chps Bryan

author
FN64 made it! (author)2012-07-19

Great "ible".. Would like to see more "ham shack knowledge" on here..
I have used acid core many times on antennas.. what you need to keep it away from are circuit boards, components, chips etc. I've never seen a problem on dipoles, j-poles or the quarter waves made on an SO-239.

My current 80M dipole is made from galv. 12.5 gauge electric fence wire.
It's balun fed & kinda in an inverted vee config... I say kinda because the apex is off the feed point by 6-8 feet.. apex runs thru a chunk of PVC pipe lashed to a tree. The tree can sway and the PVC allows the wire to slide at will. 3 years & holding strong..

73..N1MLF

author
kc8hps made it! (author)kc8hps2012-07-20

As I have time I plan to develop a collection of Ham antenna ibles.
I try to take pictures of every step so that I can put the ible together as I am able.

As you were saying about trees swaying. YES it is good to have flexibility, One of the hardest places to do that with HF is when you are mobile. If you have any brain stirs on that one please post something.

I will be posting a version of an HF counter poise coil that I have made for mobile use. (still untested) If it tunes well I will put it up here.

For those who read this, I am also a bit of a prepper/survivalist in a communications and energy sense.
I have been putting together something I am calling my "RF BOX" it contains all manner of useful things. portable wire antenna's, both HF and VHF/UHF etc.

I may do an ible on this item as well. 73 Bryan kc8hps

author
RangerJ made it! (author)2012-07-12

Glad to see a Ham Radio Instructable. It seems like a natural combination.

author
Johenix made it! (author)2012-07-10

Yes they still do make acid core and acid flux. I used it a few years ago when I replaced my own water heater.
You can use it (and probably should use it) when you make a "COPPER CACTUS" J-pole for 6 meters or above. KC0KBG

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